Bio 132 Quiz 2 - Bio 132 Section 6 Quiz Number 2 1 What are...

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Bio 132 Section 6 Quiz Number 2 1. What are the morphological differences between dark and light grown plants? Explain how etiolation helps a seedling competed successfully. Answer: Dark grown plants have long stems, underdeveloped root systems, unexpected leaves, and their shoots lack chlorophyll. 2. Cycloheximide is a drug that inhibits protein synthesis. Predict what effects cycloheximide would have on de-etiolation. Answer: Cycloheximide should inhibit de-etiolation by preventing the sythesis of new proteins necessary for de-etiolation. 3. The sexual dysfunction drug Viagra inhibits an enzyme that breaks down cyclic GMP. If tomato leaf cells have a similar enzyme, would applying Viagra to these cells cause a normal de-etiolation of aurea mutant tomato leaves ? Answer: No, applying Viagra shoul cause only a partial de-etiolation response. 4. Suggest a reason why cut flowers such as carnations are often treated with cytokinins prior took shipping. Answer: Because cytokinins delay leaf senescene and floral parts are modified leaves. Cytokins also delay the senescence of cut flowers. 5. Fusicoccin is a fungal toxin that stimulates the plasma membrane H+ pumps of plant cells? How may it affect the growth of isolated stem sections? Answer: Fusicoccin's ability to cause an increase in plasma H+ pump activity is similar to an effect of auxin and leads o an auxin-like effect, a promotion of stem cell elongation. 6. If a plant has the double mutation ctr and ein , what its it’s triple response phenotype? Explain your answer. 7. What type of feedback process is exemplified by the production of ethylene during fruit ripening? Explain (Fig 1.13 on page 11) 8. If an enzyme in the field grown soybean leaves is most active at noon and least active at midnight, is it’s activity under circadian regulation? Answer: Not necessarily.To determine if it’s under circadian control, the scientist would have to demonstrate that its activiity osicillates even when enviromental conditions are held constant. 9. A guard absentmindedly turns on the lights in. a greenhouse one night, but the plants still flower on schedule. Suggest two reasons why they were not affected by the interruption of
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darkness. Answer: Flowering of the species may have been day-neutral or required multiple exposures to short nights. 10. Some vine seedlings grow toward darkness until reaching an upright structure. This adaptation helps them “find” a shaded object to climb. How might you test whether this negative phototropism is mediated by blue-light photoreceptors or by phytochrome? Answer: You might determine which wave-lengths of light are most effective and plot on an action spectrum. If the action spectrum indicates photochrome, you could do further experiments to test for red/far-red photosensitivity.
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