Cells and Ecology: Understanding the Role of Living Organisms in Ecosystems, Lecture notes of Biology

Download Cells and Ecology: Understanding the Role of Living Organisms in Ecosystems and more Lecture notes Biology in PDF only on Docsity! Cells and Ecology Junior Science 2018 Version http://www.kwipped.com/rentals/laboratory/microscopes/324 All living things share the characteristics described in MRS C GREN Biology is the study of living things A living object is an object that carries out life functions A non-living object is an object that has not been alive A dead object is an object that was once alive All living organisms are composed of one or more cells. A cell is a small, living unit that contains all the chemicals and molecules that help support an organism's life. fire fish virus algae jellyfish coral mould bacteria amoeba crystals yeast fungus Which is Living and which is not? Use MRS C GREN Living things are classified into groups based on similarities / features Biologists classify all living things into overall groups, called Kingdoms. The members of each kingdom are alike in key ways, such as the nature of their cells, their body features or the way they obtain energy. Kingdoms have been further broken down into Phylum based on levels of similarity and then further broken down to another 5-8 levels The main groups that living things are classified into; Bacteria (Monera), Protists, Animals, Plants, Fungi Traditional classification of organisms into 5 kingdoms is based on differences in body structure After the development of microscopes, scientists discovered there was more differences at cellular level within the Monera (Bacteria) Kingdom than between all the other 4 kingdoms put together. Plant Fungi Animal Protista Monera Single celled organisms Bacteria Classes can be divided into Orders The Class of Mammals can be further divided up into many Orders. Some of the common Orders of Mammal include; Carnivores, elephants, Whales, Rodents and our Order the Primates. Although Mammals have been around as long as the dinosaurs, most of the modern Orders evolved rapidly at the start of the Palaeocene 65 Million years ago once the Dinosaurs and many other Reptile species became extinct. This left many niches open for Mammals to fill and since that time Mammals have gone on to live in the water, the air, underground and nearly every place above ground. Carnivores Seals Whales Primates Bats In the binomial system, every organism is classified given two names: First the name of the Genus that the organism is in. This is written first with a capital letter. Second the name of the species. This is written in lower case. Both names are either underlined or written in italics. The adoption of a system of binomial naming is due to Swedish botanist and physician Carolus Linnaeus (1707 – 1778) who attempted to describe the entire known natural world and gave every species a two-part name. Scientific Naming PHYLUM or Grouping of organisms is made by comparing their fossil histories, body structures, DNA, behaviour etc. The lowest level in the Classification is the species – A species is defined as all organisms that can breed together to produce viable (alive and able to reproduce) offspring. Classification System Using a simple dichotomous identification key. Rules for Using Dichotomous Keys: 1.Read both choices in a couplet (pair) carefully. 2.When reading a couplet, make sure you understand all of the terms used. 3.If you are unsure of which choice to make in a couplet, follow both forks (one at a time). After working through a couple of more couplets, it may become apparent that one fork does not fit your sample at all. 4.Work with more than one sample if at all possible. This will allow you to compare. 5.When a measurement is given make sure that you take the measurement and do not take a guess Making a simple dichotomous identification key. If we are making a key based on observations of physical features that we can see, the first step must be a feature that can divide all of the living organisms into 2 groups. For example below we could divide the birds below into those that have tuffs of feathers on their heads (spotted shag and crested penguin) and those that do not (wax-eye, brown kiwi, paradise duck, kingfisher, yellow head, spotted dotterel) Other features such as thickness of beak, tail or not, one colour or many colours – can be used to further divide each bird group. The key is finished when each individual has it’s own path and the key leads to a name for each. https://www.stampcommunity.org/topic.asp?TOPIC_ID=5934&whichpage=23 All living organisms are made up of cells. All living organisms are made up of cells, the smallest structural (how it looks) and functional (How it works) unit. Organisms can be Unicellular – consist of one independent cell, or be multicellular – organised networks of cells with different functions and structures; humans have 100 trillion cells. Organisms are divided into two groups by their cell type; Prokaryotes (Bacteria) and Eukaryotes (All other kingdoms). Cell Wall Gives the cell rigidity and a more angular appearance. Chloroplasts The site of photosynthesis, gives the cell it’s characteristic green colour Vacuole Assists with storage and structure The structure of a typical plant cell includes a cell membrane, cytoplasm, nucleus, cell wall, vacuole, and chloroplast. http://www.bbc.co.uk/bitesize/standard/biology/investigating_cells/cells_and_diffusion/revision/5/ cytoplasm Cell membrane nucleus chloroplast Cell wall vacuole Cell membrane Surrounds cell and controls passage of nutrients and chemicals. Flexible and allows cell to change shape. Cytoplasm A liquid filling the cell and containing all the chemicals the cell needs to function The structure of a typical animal cell includes a cell membrane, cytoplasm and nucleus http://www.bbc.co.uk/bitesize/standard/biology/investigating_cells/cells_and_diffusion/revision/5/ Cell membrane cytoplasm nucleus Chloroplast (Plant cells only) Location: Spread within the cytoplasm of plant cells only. Most found in plant leaves. Relative size: Can be seen with a light microscope, about 10 micro meters. Function: Site of photosynthesis converting sunlight into stored energy for the organism. Cytoplasm. Location: Contained within the cell membrane, organelles located within it. Relative size: Dependant on cell size and number and size of vacuoles within it. Function: Contains the organelles of the cell as well as the material that the cell uses for growth and reproduction. Assists the movement of materials around the cell. Gives the cell its shape. Nucleus. Location Often found in the central area of the cell within the cytoplasm. Relative size Large enough to be seen with a light microscope, often the most visible structure in the cell. Takes up to 10% of cells volume. Function It stores the cell's hereditary material, or DNA, and it coordinates the cell's activities, which include growth and reproduction (cell division). https://www.bbc.co.uk/education/guides/zr46fg8/revision/2 Vacuole. Location: Found within the cytoplasm of a cell Relative size: Can take up most of the cell in plants but tend to be much smaller in animal cells Function: In plants: important in providing structural support, as well as serving functions such as storage, waste disposal, protection, and growth. In animals: temporarily store materials or to transport substances. Plant cell Using a Microscope Most cells are to small to be clearly seen by eye and require a microscope to view. Definitions: Magnification: the number of times the image is enlarged Resolution: the clarity (how clear) and ability to see detail in the image The branch of biology relating to preparation and viewing tissue (groups of cells) under a microscope is known as Histology. Microscope parts and function arm - this attaches the eyepiece and body tube to the base. base - this supports the microscope. coarse focus adjustment - a knob that makes large adjustments to the focus. eyepiece - where you place your eye. fine focus adjustment - a knob that makes small adjustments to the focus (it is often smaller than the coarse focus knob). high-power objective - a large lens with high magnifying power. low-power objective - a small lens with low magnifying power. mirror (or illuminator) - this directs light upwards onto the slide. stage - the platform on which a slide is placed. Using a microscope safely 1. Make sure the lowest power objective lens (eg. 4x) is clicked into position. 2. Place the microscope slide on the stage and fasten it with the stage clips. 3. Look at the objective lens and the stage from the side and turn the course focus knob so the stage moves upward. Move it up as far as it will go without letting the objective touch the coverslip. 4. Look through the eyepiece and move the course focus knob down until the image comes into focus. Adjust the mirror for the greatest amount of light. Use the fine focus knob for the clearest image 6. When you have a clear image of your sample with the lowest power objective, you can change to the next objective lenses. You might need to readjust the sample into focus 7. When finished, lower the stage, click the low power lens into position and remove the slide An ecosystem includes all of the living organisms in a specific area. These systems consist of a living part called the community made up of all the plants and animals which interact with their non-living environments (weather, Earth, Sun, soil, atmosphere) which determine the habitats available. An ecosystem is the habitat and the community considered together. https://www.youtube.com/watch?v=P1X-WpfUvm4 The role of plants as producers in a community Plants are a very important part of the community as they (usually) provide all of the energy for all other living organisms through the process of photosynthesis. This energy is passed through the community by being consumed (eaten) and allows all living things to carry out the life functions (MRS C GREN) http://huckleberryfinnclc.weebly.com/producers.html The importance of plants as producers. Food entering the food chain Producers are at the beginning of a food chain. On land Producers are plants. Plants are at the beginning of every food chain that involves the Sun. All energy comes from the Sun and plants make food with that energy using the process of photosynthesis. Energy in the form of nutrients and food are passed onto other organisms when they eat (consume) the plants. There are also photosynthetic protista and bacteria (called phytoplankton )that start food chains. These will be found floating on the surface of the ocean acting as food for small unicellular animals called zooplankton. The roles of and links between organisms in a community - Habitat A habitat is a specific place, location or environment that a species may be found. Some species have more precise requirements of a habitat than others. A NZ Keas habitat is in South Island alpine regions Emperor penguins found only in the Antarctic polar region The role of producers, consumers and decomposers in food chains and webs. Three feeding roles that species can have in a community are as producers, consumers or decomposers. Producers Consumers Decomposers Plants that make food from carbon dioxide, light and water Herbivores that eat plants and carnivores that eat other animals Fungi and bacteria that break down the bodies of dead plants and animals The definition of consumers Herbivores Omnivores Carnivores Herbivores are animals that eat plants only. (plant eaters) In a food web they are directly above the producers Omnivores eat both plants and other consumers. They obtain their food from more than one source. Carnivores eat only other consumers (meat eaters). This also includes birds that eat only insects. Energy enters an ecosystem in sunlight, which is transferred to energy in plants by photosynthesis and that this energy is then passed along food chains. Trophic levels are the feeding positions in a food chain such as primary producers, herbivore, primary carnivore, etc. Green plants and phytoplankton form the first trophic level, the producers. Herbivores form the second trophic level, while carnivores form the third and even the fourth trophic levels, all called the consumers. Energy is passed from one trophic level to another starting from the producers. Food webs and food chains are used to show which species of organism is at each level and how energy moves between them. The role of producers, consumers and decomposers in food chains and webs. Food Webs In an ecosystem there are many different food chains and many of these are cross-linked to form a food web. Ultimately all plants and animals in an ecosystem are part of this complex food web. If one species in the food web changes in numbers it will affect all other species in the food web. For example if all the rabbits are removed the predators would need to start eating more of the birds, mice and rats. The grass that the rabbits ate would increase and feed more of the other herbivores. Energy losses occur along a food chain All energy that enters an ecosystem originates from the sun (with a few rare exceptions) The energy that drives an ecosystem is ultimately converted to heat, which cannot be reused and is radiated out into space. Energy flow is one way.