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| Frage | Antworten |
| Plant ecophysiology | -C utilization/ biomass production -Mineral use -Water -Stress/ adaptation -Environmental impacts' influences on growth. |
| Use of minerals | Elements required by plants are derived from minerals or mineralized during organic matter breakdown; captured in ions, then incorporated into plant structure or stored. |
| Source of nutrients | => Soil 98% are bound in organic matter (detritus, humus) Excessive nutrients can have a depressive or toxic effect. |
| Plants and water | -Plants are mainly composed by water -Relative water potential= work to make bound water into potential pure water. |
| Environmental impacts on plants | -Growth synchronization= adjusted to pst suitable conditions. -Phenological changes- timing of growing seasons can vary -An increased uptake of CO2 extends growing seasons. |
| Types of stress | =Deviation from optimal conditions -UV -Light -Drought -Cold/ frost -Temperature |
| Sun leaves | -Thicker -Bigger -More stomata (increase gas exchange) -More robust -Have more chloroplasts |
| Shade leaves | -Large surface area -Thinner -Need more thylakoids -Bigger stomata cavity to facilitate gas exchange. |
| Thylakoid | each of a number of flattened sacs inside a chloroplast, bounded by pigmented membranes on which the light reactions of photosynthesis take place, and arranged in stacks or grana. |
| Stomata | -Come in greater density the wetter the environment. -Cover 0.5-5% of leaf -Role: regulating water vapor and CO2 -Can calculate if air is humid so they can close (via guard cells) -Close if too much CO2 is arriving for photosynthesis. |
| 2 resistances through a leaf | -Boundary layer resistance (depends on shape/ size of leaf, wind speed) -Stomatal resistance (depends on number, size and how open are stomata). |
| Stomatal response to: | 1.LIGHT: Max aperture occurs at approx. 1/4 of full sunlight 2.CO2: Open as intercellular CO2 concentration decreases 3.WATER STATUS: Close as water potential in leaf decreases. 4.TEMP: Open as rises |
| Xylem composed of... | -Tracheids (small, primitive, connected by pits) -Vessels (much bigger, connected into long pipes) -Fibres: provide strength. |
| Water potential | Force with which water is attracted to the top of the tree. The cohesion-tension theory. |
| Photosynthesis equation | 6H20 + 6CO2 ==> C6H12O6 + 6 O2 |
| Photosynthesis = a 2 step process | = LIGHT and DARK reactions Photosynthesis captures photons via chloroplasts (=light reactions), splits water (releases O2), Releases CO2 to glucose. |
| Thylakoid membranes have photosynthetic pigments | -Chlorophyll a and b -Carotenoids (eg. B carotene) -Bilin pigments (ex: in red algae) assists absorption of other wavelengths. |
| When light is absorbed.... | =excitation. Absorbed molecules go to the reaction centre ==> Electron transport chain |
| Electron transport chain | -Pigment molecules serve as antennae, transferring light energy to the reaction centre. In reaction centre, electrons are transferred from chlorophyll to an acceptor molecule. -An electron donor molecule reduces chlorophyll again. -Electrons pass along a chain of acceptor and donor molecules, all sited on the thylakoid membranes. |
| Electron transport train produces.... | ...the energy (ATP) to allow 2nd stage photosynthesis (dark reactions): take up CO2 and produce carbs |
| Dark reactions | = Calvin cycle, C3 pathway. |
| Calvin Cycle | = cycle of biochemical reactions that occur in the stroma of chloroplasts during photosynthesis. Induces light independent reactions (ex: C fixation) whereby sugars and starch are ultimately produced. At tis stage, the energy produced during light reactions is used to drive the conversion of CO2 into organic molecules (glucose). |
| RUBISCO | =Enzyme that catalyzes the reaction that fixes CO2 into Calvin cycle (works best when high conc of CO2). Also catalyses O2 uptake (especially at high temperatures) ==> PHOTORESPIRATION ==> C4 pathway |
| C4 Pathway | = 2 stage process where CO2 is fixed to form a 4 carbon intermediate. Doesn't look for O2. Minimizes photorespiration. |
| Adaptation | = Evolution (of gene alleles over time) |
| Acclimation | = Physiological change allowing the organism to cope with a changed condition. |
| Chloroplast acclimation | = may adjust their position to adapt to photosynthesis --> under strong light, chloroplasts move to side of walls where they shade each other. |
| Plant temperature is determined by.. | = Air temperature: solar radiation transpiration rate wind speed. |
| Acclimation to dry conditions | =CAM pathway of photosynthesis: 1.CAM IN LIGHT: stomata shut tight; liberation of CO2 (=re-fixed in usual Calvin cycle via Rubisco); ATP, NADPH are produced as normal 2.CAM AT NIGHT: CO2 uptake and fixation occurs |
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