Biology Exam 2 Study Guide: Water Potential, Osmosis, Nutrition, Photosynthesis, Exams of Biology

Download Biology Exam 2 Study Guide: Water Potential, Osmosis, Nutrition, Photosynthesis and more Exams Biology in PDF only on Docsity! BIOLOGY 219, FALL 2006 EXAM 2 STUDY GUIDE WATER POTENTIAL AND PLANT OSMOTIC RELATIONS 1) Water Transport Mechanisms. Be able to distinguish between the different types of transport (diffusion, osmosis, and bulk flow) and be aware of examples of each type of transport in plants. 2) Water Potential. What are the effects of solutes and pressure (negative or positive) on water potential? What is the water potential of pure water at seal level (atmospheric pressure) and room temperature (23 ºC)? 3) Osmosis and Water Potential. What is osmosis? Why does osmosis stop prior to water concentration equilibrium in both osmometers and plant cells? What is the relationship between osmotic pressure and osmotic potential? 4) Osmotic Relations of Plant Cells: Be able to explain the osmotic behavior of plant cells in terms of changes in pressure and solute potential, and the effects of each on the overall water potential. What are the differences between turgid, flaccid, and plasmolyzed cells in terms of their water content and pressure potentials? 5) Role of Osmosis in the Regulation of Stomatal Aperature. What is the relationship between guard cell turgidity and stomatal aperature. What solutes are responsible for the regulation of guard cell water relations? Which solute plays the greatest role in guard cell opening? Which, in the maintenance of turgidity following opening? Why don’t guard cells increase in girth (fatten) upon absorbing water? What cell wall features contribute to the bending motion of guard cells? 6) Role of Osmosis in the Mechanism of Phloem Flow (Pressure Flow). How are differences in water potential in the phloem generated? What are the roles of sugar loading and unloading (at sources and sinks respectively) in the process? Does water necessarily flow from areas of higher to lower water potential? 7) Root Pressure and Gutation. How are root pressures generated? What solutes are accumulated and where are they accumulated at in the plant? Why is the presence of an endodermis critical for the production of root pressures? What are hydathodes and guttation? 8) Water Flow in the Xylem. What are the two types of xylem conducting cells? What characteristics do they share and how do they differ? What are the functions of pits in terms of water flow between tracheids and vessel elements? How are pressure bombs used to measure xylem water tensions? 9) Transpiration Rate and Leaf Anatomy. What is a “boundary layer”? What anatomical features of leaves affect the rate of water loss and by what mechanism? What are the effects of wind speed on boundary layer thickness? MINERAL NUTRITION – PART I 1) Mineral Nutrient Classification: What is the distinction between macronutrients and micronutrients? For what types of plants are silica and sodium essential? 2) Nutrient Deficiency Symptoms: Be familiar with the types of nutrient deficiency symptoms discussed in class and examples of specific mineral nutrients exhibiting each type of deficiency symptom. How does the mobility of nutrients affect the order of appearance of symptoms? 3) Soil Colloids and Mineral Cations: What are colloids and what types are present in most soils (inorganic vs. organic)? Why are cations, rather than anions, typically associated with soil colloids? What factors determine the direction of cation exchange between soil colloids and the soil solution? What is the lytropic series? What factors affect the strength with which cations are adbsorbed? 4) Chelation and Mineral Nutrient Acquistion: What are chelating agents and coordinate bonds? What relationship exists between the strength of chelation and the stability constant value; pH and stability constants? Be able to compare and contrast the roles of chelating agents in relation to the process of iron acquisition in cereals and dicots. In the case of dicots what factors contribute to iron release n the vicinity of the root. How does chelation affect the chemical equilibrium between salts and free ions (dissolution vs. precipitation) PHOTOSYNTHESIS – LIGHT DEPENDENT REACTIONS 1) Light-Dependent vs. Light-Independent Reactions: Be able to distinguish between both types of photosynthetic reactions in terms of their location and their functions in terms of the overall process of photosynthesis. 2) Light Absorption Basics: What relationship that exist between the wavelength of light and its energy level? What colors of light have higher energy, which have lower energy? What are the effects of light absorption at the molecular level? What differences exist between ground state and excited-state molecules? What is the relationship between the energy level of the absorbed photons and the excited state energy? How is the energy of light absorption lost from molecules? In what case, does energy loss not involve a return to the ground state configuration? What about the relationship between the energy of the photons absorbed and emitted photons in fluorescence? 3) Photosynthetic Light Absorption and Energy Transfer: What types of photosynthetic pigments are present in higher plants? Why are some of these pigments termed “accessory” pigments? What are photosystems and what are the distinct functions of the reaction center (electron transfer) and antennae complex (energy transfer)? Why are the reaction center chlorophyll a (chl a) molecules in Photosystem I and Photosystem II termed P700 and P680, respectively? In what sense are the reaction center chlorophyll molecules “energy sinks”?