25. Your future self studies a short-day plant,likea soybean plant, that uses the phytochrome system to flower in late fall. Suppose that on the first night that is long enough to stimulate flowering in this plant, you flashed red light for 30 minutes during the middle ofthe night n this short-day plant. What is the likely consequence ofthis treatment? A) Flowering would be delayed or not happen in the plant. B) Flowering would happen normally in this plant. C) Since new phytochrome protein is always made in the Pr form, there would be no effect on germination D) Flowering would happen during that night,as soon as the red-light mash stopped. E) Band Care both correct. Use the following image to answer questions 26-28 26. The fossil recordsuggests that plants have increased the number of stomata in their leaves as atmospheric CO2 levels decline. Increasing the number ofstomata per unit surface area of a leaf will contribute to which of the following? A) Decrease the rate of dehydration in leaf tissues. B) Cause a slowing of overall photosynthesis as guard cells replace mesophyll cells C) Have no effect on the rate of O2 production in the plant. D) Increase the amount of water moving through the root of the plant. E) Change the water potential of root cells 27. Imagine that this leaf was attached to a plantgrowing in well-watered soil and high lightin a small glass chamber. How will the plant respond if you exhaled repeatedly into the otherwise sealed chamber? A) stomata will close even as photosynthesis increases B) stomata will close and so photosynthesis declines C) stomata do not respond, but photosynthesis increases D) stomata will open in response to CO2 buildup E) the leaf will wilt and photosynthesis will stop due to O2 buildup
Please find the answers below and explanations in parentheses:
Answer 25: Choice 3 (Short day plant undergo flowering based upon the environmental exposure of the night. The phytochromes which are involved in flowering of the plant might get activated during night but a sufficiently long period was not available in just 30 minutes. Thus flowering will be normal in these plants in the short-day time. Secondarily, since flowering will be normal, seed germination too shall be normal because location and exposure of phtochrome to light has no direct effect on germination)
Answer 26: Choice B (Presence of excessive number of stomata and their opening can cause rapid denaturation of the photosynthetic proteins due to generation of heat on the lateral surface of the leaf. This can directly impair the rate of photosynthesis. This is why stomata are kept closed under very bright sunlight)
Answer 27: Choice B (The presence of stomata is meant for optimization of rate of photosynthesis by balancing the intake of carbondioxide. However, if concentration of carbon dioxide increases too much, the plants will not be able to respire and thus all biological functions including photosynthesis will cease.)
Answer 28: Choice B (Since there would be immediate exposure to sunlight and direct availability of carbon dioxide, the rate of photosynthesis will increase. However, owing to physical and mechanical stress due to disruption of protective outer layer, a long-term decline in activity will be observed.)
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