Tag: homeostasis in plants

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Questions Related to homeostasis in plants

Multiple choice botany transport in plant homeostasis in plants regulation of stomatal opening stomata

According to sugar concentration theory, during daytime water is drawn from adjoining cells due to

  1. Endosmosis

  2. Exosmosis

  3. Both A and B

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

According to sugar concentration theory,during daytime ,the guard cells begin photosynthesis and the sugar produced during the process increases the osmotic pressure which draws in water from the adjoining cells due to endosmosis.

Multiple choice botany transport in plant homeostasis in plants regulation of stomatal opening stomata

According to sugar concentration theory, during ............, the guard cells begin photosynthesis.

  1. Night

  2. Daytime

  3. Both A and B

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

According to the sugar concentration theory, during the daytime, the guard cells do photosynthesis. And the sugar is produced during the process and it increases the osmotic pressure which draws in the water from the adjoining cells due to endosmosis.

So the correct option is Daytime.

The correct option is B.

Multiple choice botany transport in plant homeostasis in plants regulation of stomatal opening stomata

According to the sugar concentration theory, during daytime the guard cells become

  1. Turgid.

  2. Flaccid.

  3. Placid.

  4. None of the above.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
During day time, photosynthesis occur in the guard cells and glucose is produced. Creating an osmotic gradient, resulting in movement of water from adjacent cells into the guard cells making them turgid.
So, the correct answer is 'Turgid'
Multiple choice botany transport in plant homeostasis in plants regulation of stomatal opening stomata

Who explained the scotoactive opening of stomata?

  1. Nishida

  2. Palls

  3. Ehrler

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Some stomata open during night and remain closed during the day time. This type of stomatal is called scotoactive stomata. They occur in succulents e.g., Cactus, Bryophyllum. This mechanism was explained by Nishida (1963).

Multiple choice botany transport in plant homeostasis in plants regulation of stomatal opening stomata

Porometer was developed by :

  1. Darwin

  2. Freeman

  3. Livingston

  4. Ganong
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Porometer is an instrument for measuring the area of the stomatal openings of a leaf by the amount of a gas passing through a given area of it. The porometer was first described as a method for investigating stomatal movement by Darwin.

Multiple choice botany transport in plant homeostasis in plants regulation of stomatal opening stomata

Which growth hormone is associated with stomatal movements?

  1. Auxin

  2. ABA

  3. Gibberellin

  4. Cytokinin
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

ABA is known to have a direct effect on the movement of stomata. When ABA is present, it does not allow the uptake of potassium ions which help in the opening of stomata and hence the pore closes.

Effect of ABA is countered by hormones Auxin and Cytokinin.
Gibberellins have a major contribution to cell elongation and growth.
So the correct answer is 'ABA'. 

Multiple choice botany transport in plant homeostasis in plants regulation of stomatal opening stomata

Stomata opens by

  1. Increasing solute concentration in guard cells.

  2. Weakening of cell walls of guard cell to allow them to stretch.

  3. Increasing water potential of guard cells.

  4. Decreasing the solute concentration of guard cells.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Stomata opens by increasing solute concentration in guard cells. The guard cells contain chloroplasts, so they can manufacture food by photosynthesis. The epidermal cells don't have chloroplast. Due to the presence of chloroplast, guard cell synthesizes glucose during the day time by the process of photosynthesis and so its osmotic potential increases and it withdraws water from the epidermal cell and turns turgid and the stomata opens and transpiration takes place.

So, the correct answer is option A.

Multiple choice botany transport in plant homeostasis in plants regulation of stomatal opening stomata

Consider the following statements.
a. stomata are completely absent in hydrophytes.
b. In hydrophytes, vascular bundles always have bundle sheaths.
Which of the statements given is/are correct?

  1. $1$ only
  2. $2$ only
  3. Both $1$ and $2$
  4. Neither $1$ nor $2$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Stomata are not completely absent in all hydrophytes (e.g., floating plants have them on the upper surface). Bundle sheaths are characteristic of C4 plants, not all hydrophytes.