08:48Understanding Photoperiodism: How Plants Respond To Periods of Light and DarknessUrban Leaf836views
06:23Photoperiodism II Role of Phytochromes in Flowering II Red Light and Far-red light effectBioMagica776views2rank
14:35Major plant hormones (& how to remember) | Control & Coordination | Biology | Khan AcademyKhan Academy India - English1412views
Multiple ChoiceYou are interested in determining what part of a plant senses the light, which leads to phototropism. A good first experiment would be to __________. 447views
Multiple ChoiceSome seeds require light for germination. This process is controlled by the phytochrome system. Which of the following germination treatments would inhibit germination of such seeds? 614views
Multiple ChoiceAn Alaskan trapper worried about being attacked by grizzly bears left the lights on in his cabin all the time. Plants just outside the cabin flowered a month early. Which of the following best explains this? 593views1rank
Multiple ChoiceA certain short-day plant flowers when days are less than 12 hours long. Which of the following treatments will result in flowering? 650views
Textbook QuestionEvaluate the following assertions about phototropism. Select True or False for each statement. T/F Cells on the illuminated side of a stem elongate more than cells on the shaded side. T/F Phototropism is triggered by blue light. T/F Phototropins play a significant role in phototropism. T/F The bending of the plant is due to cell elongation in response to auxin.376views
Textbook QuestionA barley mutant lacking a gibberellic acid receptor would (A) fail to make GA. (B) catalyze starch more quickly. (C) fail to make a-amylase. (D) fail to take up water.809views
Textbook QuestionAuxin enhances cell elongation in all of these ways except a. increased uptake of solutes. b. gene activation. c. acid-induced denaturation of cell wall proteins. d. cell wall loosening.685views
Textbook QuestionWhich of the following statements about phytochrome is not correct? a. It is photoreversible. b. Its function was understood long before the protein itself was isolated. c. The Pfr form activates the responses to red light. d. It is involved in guard-cell opening.481views
Textbook QuestionCharles and Francis Darwin discovered that a. auxin is responsible for phototropic curvature. b. red light is most effective in shoot phototropism. c. light destroys auxin. d. light is perceived by the tips of coleoptiles.1186views1rank
Textbook QuestionAuxin causes a shoot to bend toward light by a. causing cells to shrink on the dark side of the shoot. b. stimulating growth on the dark side of the shoot. c. causing cells to shrink on the lighted side of the shoot. d. stimulating growth on the lighted side of the shoot.626views
Textbook QuestionHow may a plant respond to severe heat stress? a. by reorienting leaves to increase evaporative cooling b. by creating air tubes for ventilation c. by producing heat-shock proteins, which may protect the plant's proteins from denaturing d. by increasing the proportion of unsaturated fatty acids in cell membranes, reducing their fluidity620views
Textbook QuestionThe signaling molecule for flowering might be released earlier than usual in a long-day plant exposed to flashes of a. far-red light during the night. b. red light during the night. c. red light followed by far-red light during the night. d. far-red light during the day.396views
Textbook QuestionIf a long-day plant has a critical night length of 9 hours, which 24-hour cycle would prevent flowering? a. 16 hours light/8 hours dark b. 14 hours light/10 hours dark c. 4 hours light/8 hours dark/4 hours light/8 hours dark d. 8 hours light/8 hours dark/light flash/8 hours dark653views
Textbook QuestionPhytochromes can be considered 'shade detectors,' while phototropins such as PHOT1 can be considered 'sunlight detectors.' Explain why these characterizations are valid.384views
Textbook QuestionIn general, small seeds that have few food reserves must be exposed to red light before they will germinate. (Lettuce is an example.) In contrast, large seeds that have substantial food reserves typically do not depend on red light as a stimulus to trigger germination. State a hypothesis to explain these observations.325views
Textbook QuestionA certain short-day plant flowers only when days are less than 12 hours long. Which of the following would cause it to flower? a. a 9-hour night and 15-hour day with 1 minute of darkness after 7 hours b. an 8-hour day and 16-hour night with a flash of white light after 8 hours c. a 13-hour night and 11-hour day with 1 minute of darkness after 6 hours d. a 12-hour day and 12-hour night with a flash of red light after 6 hours658views
Textbook QuestionA plant nursery manager tells the new night security guard to stay out of a room where chrysanthemums (which are short-day plants) are about to flower. Around midnight, the guard accidentally opens the door to the chrysanthemum room and turns on the lights for a moment. How might this affect the chrysanthemums? How could the guard correct the mistake?474views
Textbook QuestionSCIENTIFIC THINKING The discovery of auxin is a good example of how scientists build upon each other's work. For each of the three sets of researchers discussed in the chapter (the Darwins, Boyle-Jensen, and Went), write a one-sentence summary of what they discovered. If you were going to credit one person as being the 'discoverer' of auxin, who would it be?453views
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