Tag: regulation of stomatal opening

Questions Related to regulation of stomatal opening

According to sugar concentration theory, during daytime guard cells

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

  1. Bulge inwards

  2. Bulge outwards

  3. No bulging

  4. All of the above

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Correct Option: B
Explanation:

During daytime,the guard cells become turgid and buldge outwards due to their thin outer walls ,this widening the stomatal opening lying in between.

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

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

  1. Endosmosis

  2. Exosmosis

  3. Both A and B

  4. None of these

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Correct Option: A
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.

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

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

  1. Night

  2. Daytime

  3. Both A and B

  4. None of the above

Show answer
Correct Option: B
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.

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

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

  1. Turgid.

  2. Flaccid.

  3. Placid.

  4. None of the above.

Show answer
Correct Option: A
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'

Who explained the scotoactive opening of stomata?

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

  1. Nishida

  2. Palls

  3. Ehrler

  4. None of the above

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Correct Option: A
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).

Stomata opens in the night at alkaline or neutral pH(in the atmosphere of ammonia vapours). This statement was given by

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

  1. Van Helmont

  2. Van Neil

  3. Sayre

  4. Van Mohl

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Correct Option: C
Explanation:

Sayre reported that stomata open when pH is higher (7) and close when pH is low (5), i.i., high pH favours stomatal opening.

Porometer was developed by :

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

  1. Darwin

  2. Freeman

  3. Livingston

  4. Ganong

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Correct Option: A
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.

Which growth hormone is associated with stomatal movements?

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

  1. Auxin

  2. ABA

  3. Gibberellin

  4. Cytokinin

Show answer
Correct Option: B
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'. 

Stomata opens by

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

  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.

Show answer
Correct Option: A
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.

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?

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

  1. $1$ only

  2. $2$ only

  3. Both $1$ and $2$

  4. Neither $1$ nor $2$

Show answer
Correct Option: A