sintesi complete di biologia IGCSE cambridge - complete biologyIGCSE cambridge book summar, Sintesi del corso di Biologia

Scarica sintesi complete di biologia IGCSE cambridge - complete biologyIGCSE cambridge book summar e più Sintesi del corso in PDF di Biologia solo su Docsity! 1.0 - LIFE AND LIVING ORGANISM The earth was formed about 5 billion years ago, but there wasn’t the condition for life. Scientist believe that the first organisms appeared 2,8 billion years ago: they probably fed on molecules in the primordial soup. the organization in living thinks and their ability to carry out the life process depends on the energy; The RINGER’s solution is formed by ions and molecules for keep the cells alive. A living organism is so if he: -Respiration: is the chemical reaction that break down nutrient molecules in living cells to release energy for metabolism; the release of energy uses oxygen. A gaseous exchange system, supply their cells with oxygen from the environment -Irritability, so sensitivity to their environment: the ability to sense changes in the internal or external environment and to make responses: this changes are called stimuli and responses often involve movement, the change of position or place -Nutrition: the taking of materials for energy, growth and development -Growth and development: process with an organism changes in size and form, growth is a permanent increase in size and dry mass, and result from an increase in cell number/cell size. -Excretion: the removal from organisms of toxic materials, waste products of metabolism and substances in excess of requirements -Reproduction: process that make more of the same kind of organism 1.1 - THE VARIETY OF LIFE The science of placing organisms into categories on the basis of their observable characteristics is called classification; it’s important for conservation and understanding evolutionary relationship. Taxonomist place organisms into groups thanks to a classification key: the characteristics are based on morphology (shape) and anatomy (structure); there is also the dichotomous key, written as a branching or spider key (YES or NO). For the classification we have five kingdoms, containing different species: prokaryote, protocistans, plants, fungi, animals. The hierarchy of classification is: phyum (chordata-have a notochord), class (mammalia-have fur and mammary glands), order (carnivora-have well developed teeth), family (felidae-have retractable claws), genus (panthera, big cat-can roar but not purr), species (panthera leo). The two final groups are written in italics, is a worldwide convention among scientists(binominal system): The first name is the name of the genus it belongs to; The second is the name of its species. Nowdays species are classified by DNA or RNA (similar base sequences), proteine structure (have similar amino acid sequence). A part there are the viruses (different from bacteria), who doesn’t show living things characteristics: are parasites, are inside the cell of the living organism and cause harm to the host and cause diseases. The common features of them are: the genetical material (one strand; DNA or RNA), protein coat (made of subunits, protects the strand of nucleic acid), spikes (contact and recognize the cell to infect). Prokaryote doesn’t have a definite nucleus, a protoctistan have a definite nucleus and is made by different cells 1.3 - PLANTS Plants, as autotrophs, produce food molecules from simple and inorganic sources through photosynthesis using light as an energy source. They contain the light-absorbing pigment chlorophyll inside cells which have a defined cellulose cell wall. The plant kingdom can be divided into four main groups (phyla): -algae and mosses (cannot grow far from water), -ferns, better adapted life on land but only in humid areas (thin cuticles); have true roots (anchorage and absorption), stems (contains phloem and xylem, there in an underground one, the rhizome, that survive when frond die), leaves with conducting tubes (frond), and the young one are rolled up, and vascular tissues. The gametes, like those of mosses, must swim through a film of moisture to reach the site of fertilization. Have sporangia (used to remove tapeworms) which produces and releases spores. -Seed plants, flowering plants, angiosperms(enclosed seed)(80% of plants): evolved into many species and can live in almost all habitat. They are formed by: extensive root system, that absorb water and ion and anchor; a vascular system for the transport of substances; a large leaf surface for a hight rate of photos synthesis, but water losses by evaporation and diffusion through stomata (regulate it and also control the exchange of oxygen and carbon dioxide btw plant/atmosphere) are high; flowers; ovary that protects the ovules and developing embryo, particularly from drying out; fruits, former from ripened ovaries There are two major subgroups within the angiosperms: -monocotyledons, single cotyledon in the seed; one seed leaf; parallel veins on leaf -dicotyledons (eudicotyledons), two cotyledons; two seed leaves; branched veins on leaf .1.4 - INVERTEBRATE ANIMALS Animals that feed on organic molecule and doesn’t have a backbone are called invertebrates: -nematodes: eg hookworms, have bodies specialized for feeding and reproducing, ofter they are parasite in the gut of other animals; have a mouth with sucking mouthparts for drinking blood; long muscles for wriggling moment; long and thin body so not washed out of the host intestine; body is covered with mucus to resist by host digestive juices attack is soft, not waterproof. Are mainly parasites -anellids: have a long segmented body; mouth that can bite off pieces of fallen leaves; chaetae(bristles) are found on each segment, used during movement; long and cylindrical body covered with mucus layer that helps to stop drying out. is hard and slightly waterproof. Are herbivore -molluscs: soft body with no limbs; hard shell to protect the body from predators and drying out, save water; eye con tentacle; mouthparts to scarpe at vegetation; foot, muscles with a slimy covering so that can move by creeping over the surface. Are mainly herbivores but some carnivores The arthropod phylum includes:
 -crustaces: gills under shell that allow the uptake ofO2 from H2O; carapace, a thick harden shell for protection against predators; eyes, important sensors in aquatic environment; jointed limbs, flexible to help with feeding; hardened, serrated edge to claw, can hold onto slippery food and break open shells of mollusks -myriapods: antennae, sense organs in the dark and damp environment; mouthparts, with hard edges for biting vegetation or other animals, body segments, flexible for movement and wriggling around and under stones and leaves, hard exoskeleton for protection against predatore; walking legs, allow movement over brought surfaces; body covering, waterproof to help to live on land -insects: they show metamorphosis that allow to use the resources of their habitat at the maximum, they not compete, have specialized function(eg larva for feeding and growth, the adult for locomotion and reproduction). Body is segmented into head, thorax and abdomen; have three pairs of legs; mouthparts specialized for feeding; antennae, for sense chemicals in environment; compound eyes, for detect food and avoid predatore; two pairs of wings for flying -arachnids: the head and thorax are combined into one body part and then there is the abdomen; have piercing jaws, because are predators; simple eyes that help to detect the prey; four pairs of legs that allow chasing prey or holding onto web; spinneret with produces long, thin strands of sill, is has been used to make the cross hairs in the telescopic sights of rifles. 1.5 - VERTEBRATE ANIMALS The chordates are often called vertebrates, they backbone is formed by bones called vertebrae that allow to these animals to move easly. There are five classes:
 -fish: have scales covered in mucus help streamlining for swimming; operculum covering gills, gills have a large surface area for gas exchange; fins, for movement and stability, lateral line contains sense organs to detent vibration -amphibians: have nostrils leading to lungs which are used fo gas exchange, moist skin (also for g.e.), four limbs, with hind limbs webbed for walking and swimming, and wide mouth as are carnivorous energy. Some particles may be too large, and only a few cells are specialized, the particle is engulfed by the membrane. 2.3 - ALL LIVING THINGS ARE MADE UP BY ORGANIC MOLECULES Biological molecules are often called organic since were discovered in living organisms: they all contain carbon and hydrogen atoms; they are needed by organic molecules to provide energy to drive life processes, and provide raw materials for growth and repair of tissues. The study of organic and inorganic molecules that make up living organisms is called biochemistry and the sum of all the chemical reaction in living organisms is called metabolism. The large molecule are made up by subunits which can be split apart by hydrolysis, which uses water; they join in new combinations by condensation which produces water. In this way living organisms takes molecules from environment and rearrange them into shapes that suit their requirements. Four main organic chemicals used by living things; they all contain carbon and hydrogen: -carbohydrates: the simple one are the monosaccharides, are the main source of energy for many cells, are soluble, eg glucose. Through condensation became polysaccharides, are insoluble so are good stores of energy and can form important structure as such as cellulose cell wall; eg, starch and glycogen; contains carbon hydrogen and oxygen -lipids: are formed by the condensation of three molecules of fatty acid with one of glycerol, and became fats and oils, are insoluble in water so are good stores of energy and forms barrier between watery environment; contains carbon hydrogen and oxygen -proteins: are made up of long chains of subunits, they amino acids, joined together in which particular sequences are coded for by genes. There are 20 different type of them, and the sequence determines the shape of the protein. The function of the proteins depends on the shape. They are soluble so are easy transported. They contain nitrogen and sometimes sulfur -nucleic acid: in DNA these chains are coiled around one to form a double helix, the sequence bases forms a code that carries the genetic information, is passed from generation and instructs a cell to carry out particular tasks. Contains nitrogen and phosphorus 2.4 - TESTING FOR BIOCHEMICALS Since lipids are insoluble, we need to carry a physical test, known as emulsion test: is added ethanol to a solution, poured in water and if a lipid is present a milky-white emulsion is formed. To test for protein is used the biuret reagent, and will became mauve/purple; to test starch is used the iodine solution and will became deep blu-black; to test the glucose is used the Benedicts’s reagent and will became orange/brick-red. To test vitamin c is used DCPIP and the solution have to became transparent, if few drops are used, there is a strong vitamin C solution, if many drops are used there is a weak solution. A control is needed to make sure the results are valid, to show the testing is working a solution contained the substance tested should give positive results, and to show that test solutions are not contaminated, each test should be carried on a water sample and should give negative results. When comparison are made, there have to be the same condition, equal volumes, same temperature, same length of time. 2.5 - ENYMES CONTROLS BIOCHEMICAL REACTIONS IN LIVING ORGANISMS The sum of all the chemical reaction going on within a living organism is known as metabolism. Anabolic reaction bull up large molecules from smaller one and require energy, catabolic reaction break down large molecules into smaller ones and release energy. The enzymes are protein that function as biological catalyst, they speed up the reaction without themselves being changed in the reaction by reducing the activation energy. The molecules that react in the enzyme-catalyses are called substrates, and the molecules produced in the reaction are products. The enzyme that work inside the cells are intercellular enzymes as catalase and phosphorylase; the enzymes made inside the cell and then released to perform the function are extracellular enzymes and include the lipase and amylase. Enzymes are specific, and most of them work on one kind of substrate only. To form an enzyme, they bind in the active site and react to make a product. The temperature affects their activity: a higher temperature speeds up the movement of substrate molecules, so they collide and have more energy and are more likely to bind to the active site. Then, the enzyme molecules gains in energy as temperature rises, so they being to vibrate, eventually they vibrate so much that became denatured, loosing the three-dimensional shape and can no longer bind to the substrate. Each enzyme has an optimum temperature, for humans is 37° and plants 25°. Denaturation is irreversible. Also pH affects the enzyme activity: changing the acid or base condition around an enzyme molecule affects its three- dimensional shape and can denature the enzyme, they have an optimum pH and depends in which environment he is working; the pepsin has pH 2.0, they amylase has 7.5 pH. There are the activators that make the binding more likely and inhibitors, making more difficult to bind to the substrate 2.6 - ENZYMES EXPERIMENTS AND THE SCIENTIFIC METHOD The scientific method starts with and observation, that produces an hypothesis, so predictions are made. Then experiments are designed and carried out to test whether or not prediction are true. The data are analyzed and conclusions drawn. The apparatus is used to measure the effect of changing one factor on the value of a second factor. A control experiment is set up, in which the input variable is not changed and ensured that the experiment is a fair test; if there is the suspect that an error has been made, part of the experiment may be repeated taking a series of results. The raw data are gathered in a table during the experiment and can be manipulated: put the unit in the column heading, the independent variable is left- hand column, the derived from raw data are the manipulated one. Use 0 for missing values and give an informative title. Then a graph is drawn and evaluation is made, its needed to ensure that techniques and apparatus used have given the most reliable result; give an informative title, put independent variable on x- axis and dependent on y-axis, use lines to join the cross or circle mark point. The indipendente variable (input) is varied during the experiment; the dependent variable (outcome) is fixed. The fixed variable (controlled) can be categoric variable, discrete variable and continues variables. 2.7 - PHOTOSYNTHESIS AND PLANT NUTRITION The building up of complex molecules from simpler substances, synthesis, require energy and enzymes, the enzymes are in the plants cell and the energy comes from the light: this process is called photosynthesis, the process by which plants manufacture carbohydrates form raw materials using energy from light. Plants can absorb and use light energy because have green pigment, the chlorophyll that allow the energy in the sunlight to drive chemical reactions, contained in the chloroplasts, that acts as energy transducers converting light energy into chemical energy. Photosynthesis is the process in which light energy trapped by chlorophyll is used to convert carbon dioxide and water into glucose and oxygen. 6CO2 + 6H20 -> C6H12O6 + 6O2. Some of the glucose produced is stored in plants cells as starch. Plants are autotrophic, they self-feed, taking simple substances from the environment and use light energy to build them up in complex compounds, which can be eaten by heterotrophic organisms: water and minerals such as nitrate phosphate are taken from the soul, CO2 enters in the atmosphere and O2 exit as a waste product, essential for organisms. 2.8 - THE RATE OF PHOTOSYNTHESIS To test if photosynthesis has occur is needed to test the presence of starch, but this is a qualitative test, to see how quickly photosynthesis Is going on we need to use a quantitative test, for doing it we can measure the volume of oxygen released, maybe counting the bubbles. Also measuring how much carbon dioxide a plant absorb, done using leveled carbon dioxide and a geiger counter 2.9 - LEAF STRUCTURE AND PHOTOSYNTESIS To photosynthesise efficiently a leaf need: a method for exchange of gases between the leaf and its surroundings, a way of delivering water to the leaf, a system for the removal of glucose, so that can be transported to other parts of the plant and an efficient means of absorbing light energy. Leaf structure: -waxy cuticle: reduces water loss is thicker on the upper side is exposed to the rays of sun and its impermeable -upper epidermis: a complete covering one cell thick, is transparent to allow the passage of light, has the major function of preventing the entry of disease-cause organisms such as bacteria and fungi -palisade mesophyll: tall thin cells arranged in columns and separated by narrow air spaces(CO2 and H2O), contain many chloroplasts, and allow the absorption of the maximum amount of light energy -vein: is the transport system in and out of the leaf; the xylem vessels deliver water minerals and salts, and the phloem sieve tubes carry away the organic products of the photosynthesis. -spongy mesophyll: are cells loosely packed and covered with a thick layer of water, the air spaces help the diffusion of gases and are saturated with water vapor so water diffuses out of the leaf. -stomata: allow the entry of CO2 and the exit of O2, are mainly present in the lower epidermis so is less exposed to the sun. When a plant is short of water the guard cells become flaccid closing the stoma, when is plenty of water the guard cells become turgid opening the stoma. The leaf stalk hold it in the best position to receive light, the leaf have a large surface and is thin so light car be trapped and penetrate. What happens in chloroplasts: the water is a raw material for photosynthesis, energy reaches the chlorophyll molecules, the light energy splits the water molecule into O2 and hydrogen, the oxygen is released as a waste product, the hydrogen reduces the CO2 to form glucose, thanks to the catalyzing of enzymes; glucose is stored as starch, and CO2 can diffuse. 2.10 - THE CONTROL OF PHOTOSYNTHESIS Photosynthesis depends upon the availability of light, provide energy and the absorbing depends on intensity wavelength and length of time; the presence of a pigment to absorb the light, a supply of CO2 and H2O, it is the substrate that is in shortest supply respect water; and a temperature suitable for enzyme activity, important for leaves and roots. if any of these factors is in shot supply the rate will be less than its maximum possible rate in fact can cause a bottleneck, and is called limiting factor, he controls the rate of the overall process and varies at different times and conditions: in summer light and temperature are ideal, but CO2 contentration is the limiting factor; in winter on a sunny day the limiting factor is the temperature. Thanks to a greenhouse is possible to control the factor affecting photosynthesis. 2.11 - PHOTOSYNTHESIS AND THE ENVIRONMENT During respiration: glucose + oxygen -> carbon dioxide + water; if photosynthesis exceeds respiration, plant will remove CO2 and add O2; if photosynthesis is less than respiration, plants will remove O2 and add CO2. The change of CO2 levels can be demonstrated using hydrogen carbonate indicator, that sense the change in pH of carbonic acid produced by CO2. In the dark, respiration exceeds the rate of photosynthesis, the plant cell are living on the sugars; when light intensity increase, the rate of photosynthesis and respiration are balanced and there is no uptake or loss of O2 and CO2: is called compensation point, the glucose consumed by respiration is balanced by the one produced in photosynthesis. 2.12 - PLANTS AND MINERALS Plants absorb minerals from the soil in the form of ions. The minerals depend on the type of the rock beneath the soils and the decomposition of plant and animals. In cultivated soils the ground is prepared and the the crop is harvested. Levels of minerals such as nitrate and phosphate fall so they add it back in form of fertilizers: they may be natural, such as compost or artificial, the most common in NPK and contain nitrogen phosphorous and potassium.With mineral deficiency: Magnesium is absorbed by the soil as magnesium ions and form part of the chlorophyll molecule, the deficiency cause chlororisis, leaf turn yellow; nitrogen is absorbed as nitrate ions or ammonium ions, is required for many food protein and food molecules, and a deficiency makes the whole plat stunted with a weak stem and yellowing with dying leaves. The fertilizer are dangerous because runs off in rivers and make algae die, decomposed by bacteria that uses all of the oxygen, and water became oxygen-deficient making animals die. 2.13/2.14 - FOOD AND THE IDEAL DIET Food supplies the molecule with: molecules that are raw materials for repair, molecules that can be oxidized in respiration, and act as a source of energy; we are heterotrophic. The total of the molecules or nutrients that we need is called diet, a balanced one provide all the nutrients in the correct amount, 1/7 fats, 1/7 protein and 5/7 carbohydrate. needed to carry out life processes: if doesn’t provide it a person may suffer for composition to dentine, but without any canals, helps anchor the tooth to the jaw -periodontal membrane: bundle of collagen fibers, anchoring the cement to the jawbone, the tooth is held firmly but not rigidly, the periodontal membrane has many nerve endings which detect pressure. With vitamine C deficiency a tooth may fall out, scurvy. The first set is the milk dentition, at 18 months have 20 teeth, to 7-12 years, the milk one fall and replace by adult one with 32 teeth. A tooth decay begins in enamel, with no pain; it penetrated the dentine and reaches pulp, severe toothache; bacteria infect pulp and form abscess at base of the tooth, excruciating pain; decay is drilled out and hole is filled with amalgam and plastic covered again with plastic. The bacteria produce a sticky matrix that forms a plaque, that converts sugars in food to acids, these remove calcium and phosphate from enamel allowing to reach the dentine and starting a dental decay or caries. The fluoride reduces the risk of dental decay. Type of teeth: incisors, for cutting and biting; canine, for holding and cutting; premolars, for chewing and crushing; molars, for chewing and crushing 2.19 - DIGESTION PREPARE USEFUL FOOD MOLECULES FOR ABSORPTIONS Digestion is the breakdown of large, insoluble food molecules into small, water-soluble molecules, and ones mechanical and chemical processes.The food molecules are broken down by hydrolysis reactions catalyses by a series of enzymes. The saliva contains an enzyme called salivary amylase, that convert the polysaccharide starch to the soluble simpler sugar called maltose. The tongue pushes the bolus to the back of the mouth, its swallowed and entered the oesophagus. Waves of muscular contraction push the bolus down towards the stomach, and are known as peristalsis, mucus lubrificate the bolus and fiber is important so gut contents aren’t liquid. the stomach is a muscular bag with a lining that contains digestive glands, that produce: -mucus, protects stomach from the attack by gastric juices; -pepsin, a protease, or protein- digesting enzyme; -hydrochloric acid, provide acid conditions needed for the action of pepsin and denaturates the enzymes in harmful microorganisms ingested with food. In stomach the protein became amino acid, trough protease and hydrochloric acid. One che chyme is liquid, is squeezed past the pyloric sphincter and enter the donenum. The epiglottis is forced to across the top of trachea whenever food is swallowed ensuring food doesn’t enters in trachea.The digestion is completed in small intestine using the digestive juices that contain enzymes from pancreas, the intestine wall and bile from liver. From the pancreas, amylase completes it tasks, trypsin (protease) complete the task and lipase converts fats to fatty acids and glycerol, they work at 8 pH. Lipase is helped by bile, made in the liver and stored in the gall bladder, it emulsifies the fats, converts it from large globule into smaller droplets, giving a greater surface area. It also contains hydrogen carbonate to help neutralize the acid from the stomach. On the wall of small intestine there is maltase, complete the crackdown of maltose to glucose. Digestive juicy are in part made of water and mucus. Water is absorbed from the gut and indigestible food, dietary fibers are expelled: digestion 2.20 ABSORPTION AND ASSIMILATION MAKE FOOD AVAIlABLE The soluble molecules are transported across the lining of the gut into the blood or lymph: absorption. Most part happens from the ileum, the lower part of the intestine: is very long (6m), so food takes a long time to pass through, and there is enough time for absorption, the surface is highly folded, so there Is a larger surface area for absorption. the lining of the ileum is folded into tiny finger like structure, the villi, which project out into the liquid digested food. The liver sort out digested food molecules, and all foods absorbed into the capillaries are sent to the liver, and it: have at lest 500 biochemical reaction going inside the cell, manufacture bile, important for digestion of fats; storage of glucose as glycogen; interconversion of glucose and glycogen, that keeps glucose concentration constant, interconvert amino acid into others that the body might require in transamination, they can be build up to proteins including plasma such as fibrinogen; exertion of amino acid, they are removed by deamination and excited in the urine as urea; removal of old blood cells from circulation and storage of iron; breakdown of alcohol and other toxins, called detoxification. The process of moving food molecules into the cells where are used is called assimilation. Structure of villus: -epithelium: one cell thick for absorption by active transport and diffusion -goblet cell: produce mucus that protect gut lining agains digestion by body’s own enzymes; capillary, transport glucose and amino acids -lectal: transport fatty acids and glycerol -gland, lined with cells and produce digestive enzymes including maltase -vein: delivers absorbed products to the liver via the hepatic portal vein -artety: delivers blood to villi. The ileum is formed nu: longitudinal muscly layer, circular //, villi. Each villus has tiny folding called microvilli that incriace the surface area 20 times and a basement layer. 2.21 - UPTAKE OF WATER AND MINERALS BY ROOTS Water is essential to support the plant, as a reagent in biochemical processes and as a transport medium. Minerals are absorbed in the for of ions from the soils, if the spill solution is higher concentrated of ions than the root hair cell cytoplasm the ions can enter by diffusion, but works also if the concentration is in the wrong direction. The cells can select which ions entered from soils solution and any factor that affects respiration, eg lack of O2 or low temperature can reduce the uptake of ions: this because the root hair cells uses the active transport to carry out the selective uptake of ions against a concentration gradient using energy form of respiration. How water entered the root hair cell: water is drawn up by the xylem to replace the water lost: transpiration stream; dater if forced to cross the membrane and cytoplasm, the cell has the waxy material that makes them impermeable to water and permit to select which substances can enter the xylem and be distributed through the body; water cross the cortex by osmosis and function through the freely permeable cellulose cell walls; water enters root hair cells by osmosis, the soils water has a hight water potential than the cytoplasm so water moves down a water potential gradient. This begins with the loss from the leaves and completed with water absorption form the soil solution. The root hair cells have an enormous surface area 2.22 - TRANSPORT SYSTEM IN PLANTS The water and ions absorbed nu the roots may be required by cells at the growing tip, the meristem of the shoot. These long distances are carried by xylem and phloem, and collected together in groups in the vascular transport bundles. The transport system are arranged in the stem and roots to offer: most efficient transport from sources to sinks, the most effective support in air and soil. Sucrose is transported in the root to leaves in spring, but to stores in the root from photosynthesizing leaves in the summer and early autumn, the moment is from sources to sink, from the region that are absorbed or made to the region where they are stored, used. -Stem: vascular bundles are arranged in a ring with soft cortex in the centre helping support the stem: vascular bundle is formed by phloem xylem (internal) and cambium, has courtex, his cells become turgid and her to support noon woody parts, and epidermis, protects against bacteria virus and dehydration; -root: root hairs are extended cells of the epidermis: xylem (internal) and phloem form a strong central rod; cortex act as a winter storm for starch and epidermis forest against fungi. 2.23 - TRANSPIRATION: WATER MOVEMENT THROUGH THE PLANT The greatest waster loss takes place trough the stomata (singular stoma). Water movement through a plant begins with the diffusion of water vapor out of the leaf and evaporation from the leaf surface (spongy mesophyll), the 98% of water taken up by a plant is lost to the atmosphere by transpiration. The flow of water trough the plant to reduce the looses by evaporation from the leaf is called the transportation stream, and is affected by leaf structure and by conditions in the atmosphere: these factors can me investigated using a potometer. The thick, waxy cuticle reduces evaporation, leaves may be rolled with stomata in the inside and create a humid layer. Wind moves humid away from the leaf surface, hight temperature increase the water holding capacity of air, low humidity increase water potential gradient between leaf and envoirment, hight light intensity causes stomata to open which allows transpiration to occur. If wilting occur, water loos exceeds water uptake, cells become flaccid, tissue become limp and the plant is not supported. Flooding of soil with salt water lowers water potential of solution and prevent osmosis. First water is uptakes from the soils solution in root cells thanks to osmosis, water moves up the stem in xylem as a column due to the tension caused by water loss and cohesion between water molecoles, than move from xylem to enter leafe tissue down a water potential gradient, and trough transiration water evaporated lowering the water potential of tissues 2.24 - THE LEAF AND WATER LOSS Water is lost by evaporation and diffusion from the leaf surface, happens when stomata opens. Plant adaptation:
 -cacti: adapted to hot, dry enviorment, are xerophytes; have green stem to photosynthesis; leaves produces spines to reduce surface area for water loss; stomata stunk in grooves to avoid drying winds; swollen stems stores water; shallow roots absorb water from lightest rainfall; deep roots penetrate to very low water table -aquatic pond plants: have leaves with little lining in xylem since leaf is supported by water, thin cuticle, since conservation of water is not a problem, stomata on the upper to alcove CO2 uptake, are hydrophytes -wilting and leaf fall: leaves collapse are stomata close to reduce heat absorption and evaporation, diffusion of water; leaves remove chlorophyll from leaves for storage before allowing leaves to fall 2.25 - TRANSPORT SYSTEM IN ANIMALS USE BLOOD AS TRANSPORT MEDIUM To supply O2 and glucose, large organism use a transport system; the blood system, and its an example of mass flow system, which carries large volumes of fluid to all parts of the organisms. This system has -a medium: the blood which carry materials around the body; -a system of tubes: arteries and veins, carry materials; -pump: the heart, supply pressure to keep the fluid moving trough tubes; -site of exchange: capillaries, allow materials delivered by blood to enter the tissue that need them. An adult has 5dm^3 of blood with contain blood cells suspended in plasma. If a chemical is added to prevent clotting, it will separate into layer. With white blood cells and platelets in the middle. Type of cells: red blood cells (erynthrocytes): transport oxygen prom lungs to respiring tissues and prepare CO2 for the transports; contains haemoglobin, which pick up oxygen in lungs and put it in tissues; -white blood cells (phagocytes): remove any microorganism that invade the body , engulf microorganism; the irregular shape allow cell to squeeze through gaps in walls of capillaries, and enzymes in cytoplasm digest microorganisms once engulfed, the surface cell can detect microorganism; -white blood cells (lymphocytes): produces antibodies, have a large nucleus that contains many copies of genes for control of antibody protein production; -platelets; cell fragments involved in blood clotting, and can release blood-clotting enzymes. 2.25 - FUNCTION OF THE BLOOD The watery lyquid, plasma, have transport function, and carry dissolved food molecules such as glucose and amino acids, waste materials such as urea and control molecules such as hormones. Has a big heat capacity, so it can distribute around the body heating it (liver and skin). Blood has regulatory functions, homeostasis: the blood solutes affects the water potential between blood and tissue fluid, the blood solute levels regulates the movement of water. It has to be maintained at an optimum pH. protective functions: platelets, plasma protins and others, protect again blood loss and the entry of pathogens by clotting. -transport function: soluble product of digestion and absorption are transported from the gut to the liver and then to the general circulation; waste product of metabolism: transported from site production to sites of removal; respiratory gases: transported from their sites of uptake or production to site of usual or removal; hormones: transported from the site of production in glands to target organs when they have their effects; -support function: erection of penis. Hematologist study: anemia, sickle cell anemia, leukaemia, AIDS, DNA fingerprints, diabetes, eating disorder. 2.26 - THE CIRCULATORY SYSTEM blood flows around the body in a system of tube like blood vessels, and lead back to heart. the blood flows away from the heart in the vessels called arterie and flows back towards the heart in vessels called veins. joining the arteries and veins are the capillaries. the main artery is aorta, that supplies oxygenated blood at hight pressure to organs and tissue of body, and the main vein is vena cava, that return deoxygenated blood at low pressure from organs and tissue to heart. Human circulation arrangment is called double circulation because blood passes throught the heart twice for each complete circuit of the body; blood flows to the lungs under high pressure, then having picked up oxygen at the lungs, the blood receives another boost of pressure from the heart to drive it out to the tissue, where oxygen is needed. The artery have: a ticker outer wall, a thick layer of muscle and elastic fibers, a narrow central tube (lumen); a smooth lining so no obstruction to flow of food; it carries blood away from the heart to tissues, is at a hight pressure and rich in oxygen and low in carbon dioxide, the elastic walls expand and relax; the vein have: thin outer wall, thin muscle and elastic fibres, wide central tube (lumen), a flap to watch pocket valve; it carries blood from the tissue to heart, blood is at low pressure and low in oxygen and hight in carbon dioxide, the valves prevent the backflow of blood. The pulmonary artery carries deoxygenated blood which have a hight concentration of carbon dioxide; pulmonary vein carries highest oxygenated blood and lowest cabron dioxide concentration. The hepatic vein, return blood with an optimum concentration, and the hepatic one carries blood containing absorbed products of digestion from digestive powerful digestive enzymes, which destroy pathogens, then they absorb the digested products and use them for their own metabolism. The pus underneath a scab, contain dead phagocytes from accumulated toxins from pathogens; those can hide in host cell or staying in phagocyte free areas. 2.35 - ANTIBODIES AND IMMUNE RESPONDE An antibody is a protein produced by the body in response to antigen and are made by white blood cells called lymphocytes, once they learnt how to make a particular type of antibody in response to the antigen, the body begins to recover as the organisms are destroyed. After an infection some lymphocytes are kept as memory cells, which help the body to defends from further attacks: the memory may last for years and the body is immune. Immunity may be active: when individual makes his own antibodies, and can be natural, when pathogens affect individuals, artificial, when are weakened pathogens (vaccine); or passive, the individual is given ready-made antibodies, and may be natural or artificial, antibodies collected from blood of laboratory animal and stored as serum ant then injected, offers a temporary immune. Lymphocytes are find in circulating blood and in the lymph nodes, have a large nucleus and no granules in cytoplasm, are stimulated by contact with pathogens to produce antibodies, antibodies areY shaped and can recognize, bind to and help destroy antigen, the last is a protein or carhbodyrate on the surface of pathogen, able to provoke the immune system of the host. Labelled pathogens may be digested by phagocytes. Autoimmune diseases are caused by the body producing antibodies with destroy its own cell. Allergies are conditions in which the body become sensitive to a substance and over reacts to it. Transplant rejection, lymphocytes may recognize antigens on the surface of the donor organ as foreign and slowly destroys it, can over came from drugs, matching tissues. 2.36 - RESPIRATION PROVIDE THE ENERGY FOR LIFE The releasing chemical energy stored in organic food molecules and convert it to energy forms that organisms use to stay alive: respiration, set of chemical reactions that break down nutrient molecules in living cells to release energy. Respiraiton involves oxidation of food, and energy is realized during the process, glucose + oxygen -> energy + carbon dioxide + water. Respiration is the release of energy from food substances and goes on in all living cells, for energy can be used the ATP adenosine thriphospate. This process is called aerobic respiration and take place in the mitochondria 2.37- CONTRACTION OF MUSCLES REQUIRES ENERGY SUPPLIED BY RESPIRATION Muscles are collections of very long muscle fibers. Work must be done to contract muscles, the energy for this come from aerobic respiration, in rest, 70 beats and 15 breaths: the oxygen comes from the air, glucose from food digested in the gut. Muscles can release energy from food without using oxygen, by anaerobic respiration: glucose -> energy + lactic acid, 140 beats, 50 breaths in hard exercise it gives only about 1/20 of energy per glucose molecule that aerobic respiration yields, and lactic acid is poisonous, inhibits muscular contraction, if won’t builds since there ins’t enough oxygen for aerobic respiration It goes in the blood and in the body to the heart, kidney and liver, where is oxidized to pyruvate, which can be used to release energy by aerobic respiration. The organs need an extra oxygen to get rid of lactic acid: the oxygen debt, in recovery, 140 beats and 50 breaths. 2.38 - THE MEASUREMENT OF RESPIRATION Glucose + oxygen, can be used its consumption using a respirometer ->, involvement of enzymes, demonstrate by effect on temperature changes on respiration, energy, it release can be measured as a production of heat, + carbon dioxide , limewater turn milky, hydrogen carbonate indicator from red will turn orange, + water 2.39 - GAS EXCHANGE SUPPLIES OXYGEN FOR RESPIRATION Swapping oxygen for carbon dioxide is called gas exchange, take place through a gas exchange surface known as respiratory surface, is thin: short distance to diffuse; large surface: many molecules diffuse at the same time; moist: cells die if aren’t moist; well ventilated: concentration gradient of the gas are kept by fresh air; close to blood supply: gases can be carried to and from the cells that need or produce them. Is made by: a respiratory surface, membranes lining with alveoli in lungs; set of tubes to allow air from the outside to reach the respiratory surface, has many branches; a supply of blood, to carry dissolved gases to and from respiratory surface; ventilation system, to keep a good flow of air on the surface. In respiration, oxygen diffuses in red blood cells and carbon dioxide diffuses out of blood plasma, the branch of pulmonary vein returns oxygenated blood in heart; the artery delivers deoxygenated blood at hight pressure from the right ventricle. Is formed by: larynx, where air passes, produce our voice; trachea, carries air towards lungs, C-shaped rings of cartilage prevent it collapse; bronchus, first branch from the trachea, there is one to each lung; bronchiole, final, fine, leading to alveolus; alveoli, lined by membranes where gas exchange take place. The protein in haemoglobin carries oxygen 2.40 - BREATHING VENTILATES THE LUNGS Breathing Is the set of muscular movements that gives the respiratory surface a constant supply of air, this process Is brought by the action of intercostal muscles and diaphragm, the properties of the pleural membranes that surrounds the lungs, this membrane stick the outside of the lungs to the inside of the chest cavity and will follow the movement of chest wall. Air moves into the lungs along a pressure gradient, since is less then the one in the lungs, and viceversa. In breathing in: external intercostal muscles interacts and pull rib cage upwards and outwards; diaphragm muscles contract and diagram move downwards; lungs pressure increase and pressure falls, air brushes in to fill extra space and equalize the pressure; when breaths out internal intercostal relax, also used during sneezing and coughing, and all viceversa. Oxygen inspired 21% exalted 18%; carbon dioxide 0,04% and 3%. In asma air cannot move easily along the pressure gradient because, the muscle in the wall of bronchi contract, the lining of bronchi leaks a sticky mucus , can be treated with the removal of factor causing the asthma, use bronchodilator, spay with a drug. The amount of sir that enters and leaves the lungs ins measured with a spirometer, the changes are seen through a spirogram. 2.40 - EXERCISE AND BREATHING Increasing the breathing rate, more breaths per minute, increasing tidal volume, more air per beat, and the air passing from the lungs change from 8 dm^3 to 55dm^3, more CO2 coming to lungs and more blood pumped carry it away. A physical activity is any moment that use energy, exercise is physical activity that is structured and done at a certain intensity for a certain length of time. If you do too much exercise, menstrual cycle may stop, torn muscle and Achille tendon, cardiac myopathy, stress fracture. 2.41 - SMOKING DISEASE Smoking is inhaling the smoke from burning tobacco and paper, and can harm the lungs and respiratory passages because its hot, it has a drying effect, it contains harmful chemical, it irritate the lungs, and there are 1000 chemicals known in tobacco. nicotine is a chemical that causes addiction, its a stimulant that make the heart beat faster and raise blood pressure. Carbon monoxide reduces oxygen supply, when O2 and hemoglobin combine form oxyhemoglobin, the carbon monoxide reduces its formation and binds to hemoglobin making carboxyhemoglobin stable: reducing aerobic respiration and O2 transport across placenta. Tar causes cancer, which is uncontrolled division of the cells, that invade the tissue and are usually those of lining of the lower part of bronchus. it irritant Cilia are destroyed, so mucus accumulated in respiratory tubes, the microbes trap there and slide in lungs making the person coughing, this last inflames the lining of bronchi, causing bronchitis. Emphysema, the walls of air sacs are destroyed, affect white blood cells desiring lungs tissues, a chronic obstructive pulmonary disease COPD result from this. A person can work only for two meters, then get breathless. Lung cancer, stomach, pancreas and bladder, loss of limbs, coronary heart disease, lower sperm counts. Free radicals damage the proteins of DNA, but with vitamin C its effect is reduced. Richard doll’s research into smoking, through a prospective study: looking to the problem, and retrospective study: looking at the environment, lifestyle; can be multifactorial 2.43 - EXCRETION: REMOVAL OF THE WASTE PRODUCTS OF METABOLISM The waste products can be very toxic, like carbon dioxide, urea, produced in liver during deamination of excess amino acids, and denaturate enzymes; salts, can be in excess diet, can have an affect on the water potential of blood. Excretion is the removal of toxic materials. The kidneys are specialized organs that remove toxic waste product urea from the circulating blood, they carry out excretion; regulate the water content of the blood, they carry osmoregulation. Each receive a supply of blood at hight pressure through the renal artery. Each kidney contains hundreds of thousands of tubes, the nephrons, that filter the substances from the blood; each has an exit tube, the ureter, to carry away the urine; the kidney is under control by a feedback system so water saving is always exactly balanced to body’s need. The excretion system is formed by: inferior vena cava, adrenal gland, aorta, cortex, medulla, right kidney, adrenal artery and vein, renal artery: contains blood with high urea concentration; renal vein: contains blood with lower urea concentration; ureter: carries urine from kidney to bladder: stores up 500cm^3; sphincter: ring of muscle with controls flow urine from bladder to urethra; urethrea: carries urine from bladder to outside. Nephrons are formed by: branch of renal artery, contain glomerulus, blood containing wastes + useful molecules + water is delivered form circulation; bowman capsule, contains glomerulus; blood is filtered under high pressure, water + some useful molecules + water are filtered in the nephron; first coiled tube, useful molecules + most of water are selectively reabsorbed into the blood; loop of henlé alters salt concentrations in medulla to help reabsorption of water from the collecting duct; collecting duct, kidney van reabsorb water from here and return in into the blood according to the body’s demands, under the influence of anti-diuretic hormone; branch of renal veins, blood containing useful molecules and water but cleared of wastes is now returned to circulation; urine contain wastes dissolved in a small volume of water. So kidney revive blood from renal artery, remove urea end return the blood in circulation through renal vein, wastes removed from blood are expelled from body through uretra after being stored in the bladder. 2.44 - DIALYSIS AND THE TREATMENT OF KIDNEY FAILURE The collecting duct removes water from filtered solutions and osmoregulation is needed to control the amount of water returned to the blood in this way and balance it with the amount of water taken in in the diet and the amount of water lost. Is there is a kidney failure, a machine takes the blood, cleans it and returns it to the circulation: dialysis. Or is done a kidney transplant that involve the transferring from a donor to the recipient, but there may be a rejection and the immune system will attack the donor kidney destroying it. The diffusion of urea out of the blood is helped by countercurrent flow of plasma and dyalisism fluid 2.45 - HOMEOSTATIS: MANTEINING A STEADY STATE The conditions outside the body are the external factors, the one within the body are the internal factors. Keeping constant optimum conditions in the tissue fluid around the cells is called homeostasis, some organs involved in it are: cells, heart, skin, kidneys, lungs, intestine, liver. The informations about body conditions is continuously fed to the brain from sensory receptors, homeostasis depends on continual feedback of informations, is controlled by a negative feedback, changes sets off a response that cancels out the change. Any change from a set point (norm) is a deviation, which acts as a signal to control centre, which sets off the correct responses, and those cancels out the deviation and returns the factor towards it set point. When a deviation cannot be controlled by homeostasis can lead to disease 2.46 - CONTROL OF BODY TEMPERATURE Birds and mammals are endotherms, so can maintain a constant body temperature, the balancing of heat production against heat loss is achieved by a temperature control centre in the hypothalamus: this through metabolism, movement, excretion, gained or loss: convection, radiation, conduction, fats. If heat gains (respiration, conduction, convection radiation) exceed heat losses the body temperature will rise, and this may cause hyperthermia; if heat losses (evaporation, excretion, conduction, convection, radiation) exceed heat gain the body temperature will fall and may cause hypothermia. Skin increases heat loss by evaporation (sweat), radiation (vasodilatation), convection(relaxation of hair); while reduces the heat loss by: convection(contraction of hair), radiation (vascoconstriction), evaporation (no secrete); the optimum temperature is 37°: from norm-> increase->detector->integrator in brain->corrective mechanism: attempo to increase heat loss, or conserve heat-> norm. Structure of the skin: epidermis, protects against water loss and of light that enters the eye. A stimulus, makes the an impulse in sensory neurones of optic nerve, that makes an integration in the visual centre of brain, and make an impulse in motor neurones. If there is a low light intensity: radial muscle of the iris contract and the pupil is opened wider, so more light can enter and reach the retina, with hight light intensity, circular muscles of iris contract and the pupil is reduced in size so less light can enter and the retina is protected from bleaching. 2.51 - THE ENDOCRINE SYSTEM Growh and development is controlled by the endocrine system, is a series of glands, which secrete chemicals called hormones, are ductless gland so secrete the hormone in the bloodstream, and affect only their targets organs. At puberty a person became physically able to reproduce, and brain stimulates the primary sex organs, oestrogen and testosterone. The production and secretion of hormones is controlled by a negative feedback, the hormone regolate its own production: as the level of hormone in the blood rises, it inhibits its own production, and viceversa stimulates it. The ideal level of hormone in blood, if increase glands secrete too much, the hormone level acts as a signal detected by the endocrine glands, less hormone is screted so level in blood falls: the change in hormone acts as a signal to cancel out the change, and return to the ideal level. The main producing hormone glands are the adrenal glands that make adrenaline, is release when the body given a shock, skin become pale, more deep and rapid breathing, rapid heart beats, blood diverted away from digestive system to muscles using sphincters, glycogen in muscles is converted in glucose and released in blood. Testosterone in male testes and estrogen and progesterone in ovaries in female, pancreas, in insuline and glucagon, human growth hormone. The anabolic steroids increase growth of muscles, cortisone repair damaged tissues, testosterone stimulate the aggressive behaviour. Can be used in sports but can inhibit the real one action. 2.52 - DRUGS AND DISORDER OF THE NERVOUS SYSTEM A drug is a chemical substance that can modify or affect chemical reactions in the body; a medicine is a chemical treatment for an illness or disorder; antibiotics are drugs which are medicines. A lot of drugs affect the nervous system: -stimulants: promote, speed up, the action of the nervous system, make fell more confident and alert, and include amphetamines, caffeine and nicotine; nicotine mimics the natural neurotransmitters in the part of nervous system concerned with control of heartbeat and blood pressure. -depressants: inhibits, slow down, the action of some part of the nervous system, makes you feel sleepy and less anxious, but may make you dependent. eg, barbiturates, alcohol and cannabis. Alcohol affects emotional centers in the forebrain, overrules normal social restraints, at low concentration lift social inhibitions, at hight concentrations, depresses the life-support centers in the medulla, breathing may stop causing brain damage or death. It also slow down impulses in peripheral nerves, causing slow reaction, affects nerves that control blood flow to the skin, causing flushing of the skin. Can also upset normal sleep patterns by reducing the levels of calming agent in the brain. -narcotics: act like depressants but target the brain, they work as painkillers and may bring a feeling drowsy well-been or euphoria. eg heroin bring dependence, mimics the action of the body’s natural pain-killers, gives a pleasure sense of well being (affect brain); have also effects at synapses, transfer nerve impulses as chemicals neurotransmitters, changing it concentration or mimicking what they do, heorin interact with receptors normally sensitive to natural neurotransmitters. -analgesics: are mild pain-killers, eg paracetamol and aspirin, the last inhibits an enzyme involved in the response that leads to inflammation. A drug taken for non medical reasons can be describes as a social or recreational drug, the legal one gives a pleasurable sensation. An user may become dependent because they are unwilling to give up these sensations: psychological addiction; the physical addiction is when a drug is necessary for the normal working of the body, and will get withdrawal sympthoms, like vomit, tremble, abdominal pain. When a person drug himself everyday will become: malnourished because depress the appetite, get financial problems, because are expensive, infections from shared needles, including HIV and epatite and in danger from other substances mixed with. Ecstasy, means fantasy, provides a feeling of energy that make dance for long period, this cause dehydration, lead to death and disability, is cut and mixed, reduce the number of nerve cell connections in the brain, causing memory loss, is a stimulant and affect the coordination system. Alcohol: cardiovascular effects include anemia and deposits fats, skin blood vessels, sex organs stimulated, intestine irritated, pregnant water cross placenta, liver cells hard work, kidney cannot absorb water well, cancer of tongue and oesophagus. Leads to delirium tremens (DTs) causing high pulse, sweating and hallucinations. The disaster of nervous system leads to Alzheimer, multiple sclerosis, infection, broken back 2.53 - SENSITIVITY AND MOVEMENT IN PLANTS Plants respond to their environment, showing sensitivity, irritability, they respond to stimuli, changes in the environment: those are light (photo-stimulus), gravity (gravi-stimulus). A growth response carried out by a plant in response to the direction of a stimulus is called tropisms. A positive response is a growth movement towards the stimulus, and a negative response is a growth movement away from the stimulus. eg, a stem growing towards light -> positive tropism; upwards -> negative tropism; downwards -> positive gravitropism and negative phototropism. Roots are positively gravitropic: they grow in the soil, that provides water and minerals, and an extensive system of support and anchorage for the plant. Shoots are positively phototropic: leaves are in an optimum position to absorb light energy for photosynthesis, flowers are lifted in the position where they are most likely to receive pollen. growth in plants is controlled by plant hormones or plant growth substances, and are grouped together as auxin: if the tip of a young shoot is cut off, the shoot no longer respond to stimuli, this suggest the tip produce it; a shoot responding to a stimuli always bends just behind the tip, auxin travels from the tip to a region behind the tip; can be collected in blocks of agar jelly, so if decapitation occur it can respond to light; when shoot tips are accumulates on the dark side of the shoot, auxin accumulated on the dark side, affecting the growth in the dark:thanks to etiolation plant grow better in dark, receiving more water to the cells, increasing in size. Light reduces the auxin concentration on the light side, so cells absorb less water and swell less than normal, light grows less quickly and the shoot bends towards the light. Roots and shoots have different levels of sensitivity to auxin, inhibits cell growth in shoots but stimulates in shoots. Hormones can make synchronised fruiting, kill weeds, can produce seedless fruits developing without fertilisation, cutting stimulates growth 3.1 - REPRODUCTION IS AN IMPORTANT CHARACTERISTIC OF LIVING ORGANISMS An organism is living if he reproduce, and is needed to a species for survive: living organisms can pass their characteristics to the next generation, reproduce, in two ways. Asexual reproduction: involves one parent, all characteristics are passed to the offspring and are genetically identical, reproduce when condition are favorable and build up their number quickly, so rapid colonization, but doesn’t lead to variation. from a diploid parent cell, trough mitosis, become two offspring that trough mitosis divide again and again. For growing crops lead to clonation but can also clone disease. For plants its useful when arrive to a new habitat and want to make copies fast, but variation might be a disadvantage when is well suited to the environment. Sexual reproduction: require two organisms, produce sex cells (gametes), involve fertilisation, recipe genes from each parent so variation (also harmful) occur, they are all different. in crops can lead to new variety from two diploid cells one in the testis and one in the ovary, trough meiosis become two haploid gametes, and thanks to fertilization a diploid offspring is made with a set of gene fo the mother and one of the father. 3.2 - REPRODUCTION IN FLOWERING PLANTS For a species of plant to survive, the individual must be able to replace themselves; flowering plants are able to reproduce using highly adapted structures called flowers. They reproduce sexually: the young plant develops reproductive organs, maturing produces flowers under the correct light and temperature conditions; sex cells develop inside reproductive organs; male sex cells are transferred to the female one, pollination occurs; fertilization occurs, and a zygote is produced and develop into an embryo, which grows into a new young plant, and the cycle starts again. The zygote is a fruit, and it seed is dispersed to agent carriers, and under correct conditions it germinates to produce a new young plant. In the plant who are hermaphrodite, sexual parts are in the same flower. A flower is formed from a bud, which is a collection of cells at the end of a flower stalk, the cells recipe hormone messages and develop into four rings of specialized leaves, the flower: have the function of forming sex cells and make sure fertilization occur. The structure of the flower has: -stigma, the platform on which pollen grains land; flower stalk, swollen tip that acts as a base for the four sets of floral leaves; sepals, green and protect flower bud, disappear after pollination; petals, bright and scented, produce nectar, a sugary solution from the glands; carpel, female part of the flower; stamens, male part of flower: this is formed by the anther, that contain four pollen sacs filled with pollen grains each of them contain a male nucleus (gamete), and the filament, the stalk that holds in in the best position to release pollen; -style, stalks than holds the stigma in the best position to receive pollen grains; ovary, a hollow chamber, the ovules develop form its walls, which is formed by the ovary wall, micropyle, entry point for male nucleus and female nucleus in ovum. Each pollen grain is different shaped and some are released thousands years ago. 3.3 - POLLINATION: TRANSFER OF MALE SEX CELLS TO FEMALE FLOWER PARTS Pollination is the transfer of male gamers to the female part of the flower; some plants are self-sterile, have special protein in the surface of stigma that prevent pollen tubes forming if the pollen come from the antlers of the same plant; in self-pollination, pollen is transferred from anther to stigma of the same plant, is efficient but doesn’t lead to variation; in cross-pollination pollen is transferred from anther to stigma of another plant of the same species, is risky but offers genetic variation. Some agents or vector is needed to carry the pollen grains from the anthers to the stigma, flowers show adaptation to insect pollination: petals are large, bright, scented, with guide line, because insects are attracted to it; pollen is large, sticky, so attack to hair of insect b body; and wind pollination: the petals are small, no scented, have smooth pollen grains, stigma hang outside the flower. The wind-pollinated flower have the pollen with smooth coat and tiny wings to help the transfer, and happens in the colder time of the year, when there are few insects, Tiny petal to push bracts apart to expose stigma and stamen, bracts holds part of the flower, anther is held in the middle part so can shake to release pollen. 3.4 - FERTILIZATION AND THE FORMATION OF SEED AND FRUIT Fertilization is the fusion of female and male gametes, the pollen grains travels down the pollen tube to combine with nucleus in ovum. The resulting fertilized ovule develops into a seed with the zygote divides many times to produce an embryo, and sepals, petals wither away and may fall off, stamens, stigma and style wither away; then the will of ovary changes, may become dry or fleshy and in wallflower it forms a leathery pouch: now the ovary is called fruit which have the function of dispersing the seeds away from the parent plant, which helps to reduce light, water and mineral competition. Each ovule needs its own pollen grain. The carpel becomes the fruit, and ovule become the seed, not all seeds are edible because are poisoning, like cyanide and ricin. In the seed, in the micropyle, there is a small hole in the testa and allows the entry of water and O2 as seed germinates; the testa, seed coat, prevents drying out of the embryo; the cotyledons, seed leaves, may form food stores for embryo; endosperm, tissue which forms food store; plumule (young shoot), radicle (young root), together make up the embryo 3.5 - GERMINATION OF SEEDS Dispersal allow plants to spread their seeds so they can develop without competition form their parents, if environmental condition are suitable, the embryo will began to use food store in the seed and grow into a new plant: germination; these conditions are a supply of water, O2 for aerobic respiration, a suitable temperature for enzymes, because germination is controlled by them. How works: dormant seed, the embryo and food stores are surrounded by impermeable seed coat, water enters through the micropyle and activates enzymes to convert insoluble store to food stores (starch->glucose; protein->amino acid), make the tissue swell so testa in open; water and O2 enters through the gaps in testa, the O2 and glucose enable aerobic respiration, which release energy: now embryo is ready to grow. Dormancy will continue is ember if kept in anaerobic conditions, dry and cool, testa must be impermeable. Most seeds can survive longs period of poor conditions, they rest in dormancy, the low water content allow this. Hypogeal germination Antenatal care includes an advice on diet, guidance on motherhood, check of fetus and mother. The signs of pregnancy are a first missing period, and a second one with nausea, tender breasts and more frequent urination, to test for it, you measure the amount of HCG hormone in the urine, using monoclonal antibodies. In the fetus has to be check: size and position, the best is head downwards facing mothers back; heartbeat 120-160bpm; ultrasound scanning, used to produce.a picture of the fetus and provide baby’s age, size, sex, position, whether are twins and placenta position. The checks on the mother are: weight, it includes the placenta and amniotic fluid and baby; blood test of haemoglobim, blood group, German measles antibodies; urine test, blood sugars, protein (albumin); vaginal examination, for presence of infections, to obtain a cervical smear to identify cancer cells; blood presses, checked at every visit as high bp may indicate toxemia pregnancy; hormones: level of estrogen indicates how well placenta is functioning to supply the fetus with food and O2. In the first month the actual length is 7mm, the basic pattern of the body forms, is an embryo; in two moths is 13mm, all adult organs present, muscles begin to differenziate and embryo can move, sex organ are seen, bones become harder, nots is a fetus, drug affect the development. In the 3 month is 70 mm, fetus may kick, curl toes, sex can be determinated, lymph nodes develop; 4 months 95mm, face begins to look human, movement may be vigorous. In 7-9 month, preterm babies have a good change to survival with assistance 3.12: BIRTH AND NEWBORN BABY The sequence of events that lead to the birth of baby is called labour and begins with contractions of uterus muscle: are prevented by progesterone, level of this falls, stimulates oxytocin, helped by oestrogen, the level rises. Baby lines with head against cervix, contractions start every 20 minutes, and cause the amniotic fluid break and release amniotic fluid, cervix dilate: Breaking the waters. Baby head pass through cervix, now the birth canal and he born. He can have a short of oxygen as the umbilical cord is compressed, the cord is clamped and cut, placenta comes away as the afterbirth. The baby suck the nipple: suckling reflex, stimulates mother to release oxytocin, and causes tiny muscles in mammary glands to squeeze out milk: lactation. Mother milk is the ideal food, contain all nutrients, little food, antibodies, and the one made the first days is called: colostrum. Around six moths first teeth appear and can eat solid food: weaning, form solid to liquid. Human milk, is low in bacteria, there are fewer infections, less mortality, is low cost and at body temperature, no preparation, encourage social bond, suckling may have a contraceptive effect, hight in lactose, casein, mineral, fats, and three time hight of protein . Artificial milk is based on cows milk, and dried powders are added, you can know the exact quantity, its expensive and not easy digested, it have to be clean otherwise microbes pass to the baby, can lead to gastrointestinal upset and efficiency diease, lactose intolerance, protein curd in stomach. Mother after baby born have to do exercises to strengthen, placenta wound remains for four-six weeks inside, and lochia is discharger, urinary system have to be kept clean, so do regular bathing with salt. The baby temperature start begins efficient, the room has to be at 20°, bathed once a day, before a meal, wash mother hands after feeding, bottles cleaned, teats washed and boiled. Occasionally two embryo develop together, each in its own placenta and umbilical cord: twins, three or more ova are released and fertilized at the same time, in multiple birth: common in women treated with fertility drug, and gives early birth. Identical twins, with the same set of genes: the zygote slips into two identical embryos, when a single ovum is released; non identical twins, when two ova are released, each zygote forms an embryo. A rare event is the conjugative conception; an ovum is released, a second is released before the ovary switches of by feedback inhibition, the mum is fertilized, and the other could fertilize a month later, maybe is a sperm of a different man 3.13 - SEXUALLY TRANSMITTED INFECTIONS The control of sexually transmitted infections requires the interaction of individuals and community, are transmitted by body fluid through sexual contact. Preventing by use a condom, have medical check, know the history of the parents. They can be caused by bacteria, virus, fungi. Bacterial STIs are treated with antibiotics but resistant strains are developing; viral STIs are increasing in frequency, including AIDS: HERE IMMUNE SYSTEM BEGINS TO FOOL AND THERE IS NO CURE. Gonorrhea, is caused by bacterium, burning urine, inflammation of testicles, penetrative sex, cure with antibiotics 3.14 - VARIATION AND INHERITANCE Some features differ from one person to the next: those are the individual variation; these features may be inherited from the parents: inheritance is the transmission of genetic information from generation to generation. Examples of these inherited, or hereditary characteristics include the tendency to develop some diseases and the permanent color of the skin; they cannot usually be altered, except temporarily. Some cannot be inherited, and are called acquired characteristics and they can be changed. The study of inherited characteristics, and the way they are passed from one generation to another is called genetics. The reproduction of offspring by sexual reproduction involves: -the gametes are formed by cell division -the organism develops from a single -the production of gametes and fertilization fertilized egg by cell division -the nucleus of the male gamete goes to form the nucleus The chromosomes are stains used to show up the contents of the nucleus; they are formed by: -centromere: the attachment point for spindle fibers during cell division -nucleus: contain 23 pair, so 46 in total -gene: a length of DNA that code for a specific protein, its a section, and carry the coded information for the production of a protein by the cell -each chromosome contains long coiled strands of DNA, about 2 meters (stretch to the moon and back). The chromosome carry the genetic information that fives particular characteristics to a cell: -if section of chromosome are transferred from one cell to another, the characteristics of the recipient cell change; if the chromosomes are damaged, the characteristics of the cell change -the chromosome swell when proteins are manufactured in the cell. So a chromosome is a thread-like structure of DNA, carrying genetic information in the form of genes 3.15 - DNA, PROTEINS AND THE CHARACTERISTICS OF ORGANISMS The characteristics that a cell or organism possesses defends on the proteins that the cell can manufacture. The instruction as to which proteins should be manufactured at any one time in a cell are carried as genes on the chromosome; the latter are composed by molecule called deoxyribonucleic acid or DNA: the DNA as a gene controls the production of protein that is responsible for characteristic; The DNA carries its instruction using four different chemical compounds called nucleotide bases or organic bases. The DNA is made up by nucleotides, that contains a base and a sugar-phosphate backbone. They contain the base adenine (A), guanine (G), cytosine (C) and thymine (T). The base pairs are: A-T; G-C: about 600 base pairs are needed to code for an average protein. Certain physical forces cause the ladder to twist around itself to form the double helix shape, similar to a spiral. For one organism to pass on characteristics to its offspring, it must be copy the coded instruction: DNA must be replicated and it have to do it with a great accuracy. In replication, the two chains separare and each strand acts as a template for making another strand using a supply of nucleotides: the order of the bases on each new stand is determinate by the order bass on template. They join together with new template and two section are made: originally identical to one other, and identical to the section. The discovery of DNA depends on the work of Rosalind Franklin, James Watson and Francis Crick. 3.16 - HOW THE CODE IS CARRIED Each gene carries a series of coded instructions for the synthesis of proteins, each instruction is made up of three bases in a certain sequence, each triplet respond to a single amino acid in the protein. The sequence of bases in DNA is a series of coded instruction for building up amino acids into proteins, each triplet build a different amino acid into the protein. The coded information in the genes is located on the chromosome, with are in the nucleus. The ribosome, protein-manufacturing station, is found outside the nucleus, in the cytoplasm: the code is carried by a nucleic acid, the messenger RNA (mRNA). The mRNA is made un by transcription: the base sequence in the DNA is transcribed into another base sequence the mRNA; the mRNA never contain thymine, but uracil (U). The building up of a protein by a sequence of amino acid by a sequences of bases in the mRNA is called translation. The protein haemoglobin gives the characteristic of oxygen transport to red blood cells; the cell specialization depends on protein, the cell only makes the specific proteins it need to carry out its specialized function 3.17 - CELL DIVISION Each chromosome has a partner, forming homologous pairs: have the same genes in the same position. The cell division in which the new cells are copies of the parent cell is called mitosis. Thanks to mitosis, in animals each tissue provides its own new cells when they are needed; the stem cells are unspecialized cells that divide by mitosis to produce daughter cells that can become specialized for specific function; in plants, cell division in the cambium increase the plant with, and cell division in the meristem at the tip of the roots and shoots leads to an increase in light. How mitosis go: -the DNA is replicated and each chromosome becomes two identical chromatids joined at the centromere. -chromosomes become attached to a spindle, a fiber with run from one pole to another; the chromosome line up at the equator, midline, of the cell. The centromere divides and spindle fibers shorted so that two chromatids in each chromosome separate, and move to the opposite ends of the cell. -the cell membrane pinches in to separate the two sets of chromatids into two cells: now we have daughter cells: identical one to another, to the parent cell and with the same number of chromosome. The number of chromosome is the diploid number (2n); the number of chromosomes in a gamete is the haploid number (n). Fertilisation is the fusion of haploid gametes to restore the diploid number in the zygote formed by meiosis or reduction division, because it halves the number of chromosome in the cell: -the chromosomes line up, and replication occurs, so each chromosome became two identical chromatids -they line at the equator and the spindle divides the whole chromosomes: now each cell has one chromosome from each homologous pair. Then the chromosome separates in two chromatids and four gametes, each containing one set are made. 3.18 - INHERITANCE The gene code for characteristics, such the color of the eye; the alternative forms of the gene is called allele: if it’s the same is called homozygous and if its different is called heterozygous. Two individuals with are homozygous for the same characteristic and breed together will be pure-breeding: all the characteristics will be passed on the offspring. The dominant allele is the one that shows up in the phenotype (color of eye) of these cells, and the recessive allele is the one that is hidden in the phenotype of these cells. 3.19 - STUDYING PATTERNS OF INHERITANCE Genetics is the study of inheritance, through a homozygous cross BB and bb, er get Bb first generation; thorough two heterozygous Bb, we gat BB, Bb, Bb, bb genotype. These crosses result are probabilities. Test cross is a test between an individual with a dominant phenotype but unknown genotype and an individual with a recessive phenotype (which can only be homozygous) which aims to determine the genotype of the first individual. 3:1 ration -> phenotypes are heterozugous; 1:1 one heterozygous, one homozygous recessive. If any offspring showing the recessive result, parents must be heterozygous 3.20 - INHERITED MEDICAL CONDITIONS AND CODOMINANCE Albinism is caused by a recessive allele, the carriers of the mutant are affected, not the heterozygous, they have a recessive allele.if a person have a sickle cell anemia, can be also resistant to malaria, if has the normal allele, and sickly cell allele. For some genes there is a multi allelic inheritance, there are 3 allele: the blood group: A and B are dominant. Ia produce antigen A: AAAO -> blood type A (same for B) I0 is recessive, as AB, and makes blood type O or AB; Rh produce antigen Rh, the recessive one doesn’t produce it. O- is universal donor, AB+ is the universal acceptor. 3.21 - SEX IS DETERMINED BY X AND Y CHROMOSOMES -domestic dogs are same species but some have been bred for appearance, some for hunting and some as aggressive guards.. -wheat: has been bred so that all the stems are the same height and the ears separate easily from the stalk. What appear to humans ad a valuable characteristic might not always be valuable in natural selection. For example a chivuawa will not survive in the wild, because he is more suitable as a pet. Larger cattle carry more meat, so are valuable to a butcher and are allowed to breed and produce a litter. If the size is inherited, the next generation may contain individuals that are even bigger, and than a large individual may be mated with one of its parents for make even larger animals with more meat. Male animals cannot give birth to young animals so: their offspring will be fattened up for selling as meat, desirable males may be electricallt stimulated to eiaculate and sperm is collected and frozen, the sperm can be taken to a cattle breeding farm and used to inseminate females. Diffrences: in artificial selection humans are the agents of selection, is much quiker, and offers no advantage to the animal or plant in its natural enviornment, while natural selection depends upon the natural environment. Its likely that selective breeding will be replaced by genetic engeniiring. Artificial selection has produced many vegetables from one ancestor species. Selective breeding involves the mixing of genes ar meiosis and fertilization, but once a plant breeder has bred a plant with a desirable characteristic, then asexual reproduction must be used to male many copies of it 4.1 - ECOLOGY AND ECOSYSTEM There are three survival essentials: supply of food, shelter from undesirable physical conditions and a breeding site. The living organisms interacts with its environment, eg a living plant: removes carbon dioxide, water and light energy from its habitat, may be eaten by an animal or parasite. Factors in the environment affects the growth of the plants. -Some are biotic, other living organisms: predators, food, mates -and some are abiotic, non living factors of the habitat: physical: O2 and CO2 concentration, light intensity, water availability; climate: the lowest and highest temperature, the humidity Ecology is the study of living organisms in relation to their environment: the interaction. The ability of the habitats to supply living organisms with their requirements may vary at different times of year; this will be followed by predators with feed on animals. The animal migration seen in east africa result from the changing of conditions: poor rain means little growth of grass, herbivores leave for areas of fresh growth, carnivores follow erbivore. Names of groups of living organism and the way they interact with abiotic environment: -a population: all the members of the same species in a particular area -a community: all the population of living organisms in one area. The community is the biotic environment -an ecosystem: all the non/living-organism factor interacting together in a particular part of the environment -a habitat: a part of the environment that can provide food, shelter and a breeding site for living organisms Air, water and soil make up the abiotic environment 4.2 - FLOWS OF ENERGY: FOOD CHAINS AND FOOD WEBS During feeding one organism is obtaining food, energy and raw materials, from another one. The flow of energy between organisms in the ecosystem can be shown in a food chain. The amount of energy passed on in a food chain is reduced at every step, lost and converted (e.g. respiration->heat). Since little energy is transferred from the base to the top of a chain, a top carnivore must eat many herbivores: this ones, feed on many different plants. All these interconnected food chains in one part on an ecosystem can be shown in a food web: the more complicated is, the more stable the community is. Food chains show energy flow throw an ecosystem; the position of each organism in the food chain represents a different trophic (feeding) level: -sunlight: provides energy to dive food chain -producers: autothropic organisms, usually green plants, make their own nutrients using energy from sunlight through photosynthesis -consumers: organisms that obtain food energy by feeding on other organisms; primary consumers are herbivores, they obtain energy in food compounds obtained from producers. secondary consumers are carnivores, they obtain their energy by eating other animals: they may be eaten by tertiary consumers. -decomposers: as fungi and many bacteria obtain energy and raw materials from wastes and remains of the other organisms. -the final consumer in the food chain is called top carnivore In the chain the organisms tend to get bigger bicause they have to be large enough to overcome the prey and an organism eats several organisms below to obtain enough energy Energy transfer: they energy flow is not cyclic: sunlight -> biochemical bond energy -> heat; there must be a continuous input of light energy to drive life in an ecosystem: -less than 1% of the energy released from the sun falls onto leaves -energy fixed by producers: 5-8% of energy falls onto their leaves because some is transmitted, some is reflected, some is not the correct wave length(red or blue light) -the energy transfer to primary consumers, is only 5-10%: much of plant body is indigestible, consumer rarely eats whole plant, roots or stems may be lest behind -energy is transfer to secondary consumers is between 10 and 20%: animal material has a higher energy value and animal material is more digestible. -energy transferred to decomposer is very variable, but eventually the entire energy. Content of animal and plant will be released as heat from inefficient respiration -respiration losses occur form each trophic level. Respiration is not 100% efficient and eventually all of his energy is lost as heat. Because of this food chains rarely have more than 4 or 5 tropic levels. FOOD WEBS AND FOOD CHAINS Humans have a negative effect on food chains and webs: they over-harvest food species such as cod and by introducing foreign species to habitats. The food chains and webs in aquatic environments can be longer than those on the land: there is the space and ideal growth conditions for many producers, even with evenrgy looses at every stage there is enough trapped energy for more steps in the chain: many of the chains began with phytoplankton or algae. Seashore in as excellent environment for animals, at least as far as food is concerned, because fresh supplies are delivered with every tide: some of the top predators need so much food that they need to travel between different part od the habitat. Catching crabs for human food could: increase number of anemones with could reduce amount of zooplankton, with could increase the amount of phytoplankton, with could increase the number of jellyfish. 4.3 - FEEDING RELATIONSHIPS: PYRAMIDS OF NUMBERS, BIOMASS AND ENERGY Food chains and food webs provide qualitative information about an ecosystem, but for a quantitative information we ca use: -pyramids of numbers: is a diagrammatic representation of the number of different organisms at each tropic level in an ecosystem at any time. The number of organisms is represented by the length, or area of a rectangle; and moving up the pyramid, the number of organisms generally decreases, but the size of each individual increases. Some problems may be that the range of numbers is enormous so drawing the pyramid to scale is difficult. Then, pyramids may be inverted, particularly if the producer is very large or parasite fed on consumers. -pyramids of biomass: represent the biomass (number of individuals x mass of each individual) at each tropic level at the time when the sample is taken: this should solve the scale and inversion problems. Is expressed as unit of mass per unit area, kg/m^2
 -pyramids of energy: measure the amount of energy flowing through an ecosystem over a period of time, that is usually a year since takes into account the changing rates of growth and reproduction in different season; it is possible to add a base layer representing the solar energy. Its expressed as units of energy per unit area per unit time, kJ/m^2 * year 4.4 - DECADY (DECOMPOSITION) IS A NATURAL PROCESS many building material are natural and the environment treats these as dead remains of once-living organisms, it reclaims the nutrients and return them to the ecosystem to be reused. The nutrients are usually recycled by living organisms, such as scavengers which break up the dead bodies into more manageable pieces: they eat some pieces of the body and leave behind blood and pieces of tissue. The remains that are left are decomposed by the feeding activities of microorganisms, that are fungi and bacteria and they feed by secreting enzymes into remains and absorbing the digested products: this is called saprotrophic feeding. The decay provides energy and raw materials for the decomposers and releases nutrients from the bodies of dead animals and plants which can be used for other one. For example the sugar in dead rabbit, trough the restoration by microorganisms, -> carbon dioxide that thanks photosynthesis became sugar in plants. In this way the substances pas through nutrient cycles as microbes convert them from large, complex molecules in animal and plants remains to simpler compounds in the soil and the atmosphere. A saprotrophs is formed by:
 -cytoplasm and cell wall -the cell nourish themselves by secreting enzymes into food and absorbing the products -lipase(fats->fatty acid + glycerol), amylase (starch-> maltose-> glucose) and proteases (protein-> amino acids) are converted in simpler substances -the complex organic compounds (include fats, proteins and starches) became, threw environmental factors that may affect decomposition simple compounds (include fatty acids, glucose, amino acids, and minerals). Those are absorbed by diffusion and/or active transport. The metabolism cell uses the absorbed products for respirator or for cell growth and division. The environmental factors are: -heat, for rapid decomposition, need to maintain an optimum temperature for the activity of enzymes, heat is produced by respiration that occurs during the decomposition process -oxygen, that is required for aerobic respiration which releases energy to drive the metabolisms; in the absence of it, decomposition is slow and very smelly, as methane and hydrogen sulfide may be produced -water, many decomposition reactions are hydrolysis reactions, is necessary to breakdown products before they can be absorbed by saprotrophs and other organisms The antiseptics and disinfectants kill the living organisms that carry out the decay process, is good for hospitals and food preservation, but bad in heaps and sewage works. 4.5 - THE CARBON DIOXIDE CYCLE Living organisms require carbon-containing compounds as: -a source of energy: released when the carbon-containing compounds are oxidized during respiration, particularly carbohydrates and fats -raw materials: for the growth of cells, particularly fats and proteins The process of feeding, respiration, photosynthesis and decomposition recycle the carbon; the amount of CO2 released by photosynthesis should be equal to the amount released in respiration: the CO2 remains about at the same concentrations, about 0.03% of the atmosphere. Processes that can affect the regular cycling: -the conditions are not suitable for respiration by decomposers, so it remains in complex carbon compounds in the body; e.g anaerobic, low pH, low O2 concentration, extreme temperature will inhibit decomposition -> fossil fuels laid down in environment -fossil fuels have been used as a source of energy, and combustion of oil, gas, coal and peat has returned the volumes of CO2 int he atmosphere, increasing the concentration. -burning biomass fuels, like wood and alcohol, uses up oxygen and return CO2. Plants respire less than they photosynthesis and the decomposers respiration may be very high in some environments e.g the warm, moist condition in a rain forest, decomposer can contribute 80% of CO2 in that environment. How the carbon cycle works:
 -the organic compounds in plants (carbohydrates, fats, proteins) thought feeding became organic compounds in animals and through death and exertion (provide plant and animal material for decay) became organic compounds in decomposers; organic compound in plants may became directly organic compound for decomposers trough death and excretion, in nucleus; flagella, may be one (flagellum) or several, which move it. Binary fission can be so fast that a bacterial population can grow quickly, when condition prevent growth, bacterial cells survive producing hard- coated spores, is difficult to kill, only with sterilization. In the exponential phase: population grows every 20 minutes, require amino acids, carbohydrates, water, suitable temperature, can produce complex molecules, same genetic code, have plasmids, extra DNA piece, to carry genes from one cell to another; in the stationary phase: population number that die is balanced with the one produced, the rate is limited by: availability of nutrient, oxygen water, temperature, ph, production of wastes increase the death number. Death phase: population falls as number of deaths exceed number of produced, caused by shortage of resources affecting stationary phase. 4.11 - HUMANS USE ENZYMES FROM BACTERIA The majority of enzymes used commercially are obtained from microbial sources, usually fungi or bacteria, they grow in controlled conditions in a fermenter. Lipids and proteins stains are difficult to remove from clothes, and can be used lipase, also for chocolate flow and protease powder; protease is used also for soften the gluten; pectinase breaks down clumps of plant cell. Some enzymes are immobilized on a carrier of fibers and can be reused many times; eg immobilized lactase breaks down lactose. Fermenters are used also in fuel production and the manufacture of the antibiotic penicillin. A bioreactor have to stay in sterile conditions. In batch culture there is a fixed input of nutrients and the products are collected by emptying the bioreactor, is expensive but, have advantages: vessels can be switched and contamination relates in the loos of a single batch; in continuous culture fresh nutrients are added as soon as they are consumed and reactor may run for long periods, is more economical but contamination causes losses, the culture may block inlet or outlet pipes. If formed by a microbe input and nutrient input, a paddle stirrer mixing contents, can be also carried out by an airstream for aerobic fermentations, gas outlet, constant temperature water jacket, probes monitor conditions, further processing of product for separate microorganisms from the product, and separate product for sale or distribution and involve drying and crystallization 4.12 - USING FUNGI TO PRODUCE ANTIBIOTICS: DRUGS TO CONTROL BACTERIAL DESEASE A product made by one microorganism to kill another one is called antibiotic: the first was penicillin, they inhibits bacteria development and only affect bacterial cell. Penicillin is a secondary metabolic product, made when growth of the producer organism is slowing down rather when it is at his maximum, it has to be kept sterile, at 24° and ph 7.5. Bactericidal antibiotics kill the pathogen directly, whereas bacteriostatic ones prevent it reproducing, leaving the host defense to kill existing pathogens. As The use of them increases, strains of bacteria that are resistant to the antibodies are developing. The optimum time to collect penicillin, is after main growth of model fungus, collect the batch and filter liquid, then is crystallized and put in capsules. An antibiotic is used to treat bacterial infection; an antiseptic can be used to prevent infection, chemicals applied of the body. Disinfectants are chemicals that kill microbes but are more powerful and used on worksurfaces. Penicillin is bactericidal at high concentrations, but may lead to resistance so is given a the bacteriostatic doses, where the number does not reach dangerous levels and eventually hits immune system removes bacteria, in the control phase there is no antibiotic treatment. Antibiotic-resistant strains of bacteria are formed by artificial selection, more likely to happen if antibiotic are used unnecessarily. Some bacteria resist to penicilin because produce penicillate. The antibiotic does not create the resistance but selects it in the population, is the selection pressure, and resistance is the survival advantage. 4.13 - BAKING AND BREWING: THE ECONOMIC IMPORTANCE OF YEAST Much of the commercial use of microorganism is based on fermentation: it covers any metabolic process carried out using carbohydrate as a starting material. The anaerobic respiration of glucose by the single cell fungus yeast: glucose->carbon dioxide + ethanol + energy, is a alcoholic fermentation; for yeast useful product is energy, the other are by-products. If alcohol concentration get higher than 8/9% yeast is killed and fermentation stops. The process of baking and brewing: when ingredients are mixed with yeast: kneading and produces dough -> is kept in warm, yeast ferments sugar and bubbles of CO2 are trapped in proteins, so rises -> baking kills yeast and stop fermentation, alcohol evaporate, forms a crust harden the other -> bread is produced, spongy texture because of CO2, fresh smelly from a alcohol. Wholemeal is make with flour that had the not the husk removed from wheat. 4.14 - MORAL BENEFITS ABOUT GENETIC ENGINEERING Genetic engineering is the modification of the genome of an organism by the insertion of.a desired gene from another organism, enabling the formation of organism with beneficial characteristic. DNA is transferred to the DNA of another organism, to make a new combination of DNA is referred to as recombinant DNA technology, technology permit to overcome to problems thanks to: enzymes that cut DNA and pst it into another; vectors that can carry the gene from one organism to another; culture techniques to allow large quantity of product to be produced and collected, even if the host doesn’t produce it. Advantages are that the product is made in large quantities and its not expensive, te process can be switched on or off easly. (Guarda pagina 253) 4.14 - MORAL BENEFITS ABOUT GENETIC ENGINEERING The benefits of genetically modified products: engineering organisms can offer higher yields from fewer resources, but plants enginneerd for pesticide resistance could cross-pollinate with wind relatives, creating superweeds; crops engineers to cope with extreme environmental conditions will open up new cultivation areas and reduce the risk of famine, but engineered bacteria may escape from laboratory or factory; genetic engineering gives more predictable results than selective breeding, but new organisms might be patented; foods can be engineered to be more convenient, but how far should we allow research into human gene transfer to? Gene therapy is the transfer of health human gene into a person cells that contain mutant allele which cause disease: the empty virus coat act as a gene vector + health copy of gene -> virus take up healthy gene, virus infect diseased cell and release healthy gene, cell can now make protein product, it repair the diseased cell. Cystic fibrosis is a good candidate for the therapy because the healthy gene is easy identified and obtained, disease tissue in lungs is easy to reach via teaches and bronchi, the coat of an influenza virus can be used as a gene vector 4.21 - MANAGING FISH STOCKS: SCIENCE AND THE FISHING INDUSTRY In late 1960 herring fishing become efficient, and as a result North Atlantic herring population fell, the reason for this also include: -shoal location becomes more efficient as radar system become freely available; -larger and safer boats, so fishers could remain further from port even in bad weather; -fishing was often mixed, fishing for one species would catch other species of the similar size that may not be at the same growth state and population cannot be maintained. European Union now control the herring fishing, thanks to measurement to limit overfishing such as: -control of mesh: the size and shape allow immature fish to exape; -setting of quotas: in 1983 EU set up a common fisheries policy in attempt to limit the size of catches, this quota vas reduced by scientist, but the population of herring didn’t recover, because Fishermans catch more than their quota and throw away the less marketable fish, which may be damaged by capture and did not survive to reproduce; -protection of fisheries: EU set s limit of 320km around their waters to control fishing in non-EU countries, but were very difficult to enforce, and led to confrontations between fisherman and governments; -reduction of fishing fleets: governments have to provide subsidies to fisherman who livelihood has been treated by the measures. British government was reluctant to support and have devoted herring fishing. Fisherman’s want ro make a living and don’t allow herring to recover: the scientist can advise, the government have to act. Francesca Romana Amori Ⓒ