Which of the following would trigger opening of stomata? a. extreme heat b. nigh

Question

Which of the following would trigger opening of stomata? a. extreme heat b. nightfall c. loss of potassium by guard cells d. swelling of guard cells due to osmosis e. all of the above Stomata open during the day in response to a. blue light triggering the efflux of K' from guard cells b. increased temperatures c. increased CO_2 levels d. blue light triggering the uptake of K^+ by guard cells. e. the production of abscisic acid Xerophytes minimize water loss by a. using the CAM pathway. b using the C3 pathway c. reducing the thickness of the leaf cuticle d. developing a Casparian strip between their leaves & stem e. having leaves with a large surface area to volume ratio. Sugar moves from leaves into the__of__ by____ A) tracheids, phloem, diffusion B) sieve-tube members, xylem; active transport C) tracheids; phloem, active transport D) sieve-lube members; phloem, active transport E) sieve-tube members, phloem, diffusion

Explanation / Answer

Answer 17: d. swelling of guard cells due to osmosis. (Explained as below)

During the day guard cells take in water by means of osmosis and swell up. Swelling of guard cells opens the stomata and enables transpiration.

Answer 18: d. blue light triggering the uptake of K+ by guard cells. (Explained as below)

Blue light induces the guard cells. Uptake of K+, causes the guard cells to swell and thereby open the stomata.

Answer 19: a. using CAM pathway. (Explained as below)

Xerophytes like desert plants must produce food under abnormal conditions of temperature and inadequate supply of water. So, they develop an alternative mechanism of photosynthesis, CAM photosynthesis. To conserve water within the plant body, the stomata remain closed during the day and open at night.

Answer 20: e. sieve-tube members, phloem, diffusion. (Explained as below)

The sugars are transported from the leaves into the sieve tubes of the phloem by means of osmosis and not active pressure.

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