Tag: botany

Questions Related to botany

Active K$^+$ mechanism of opening and closing of the stomata was given by

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

  1. Darwin

  2. Leuitt

  3. Scarth

  4. Khorana

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Correct Option: B
Explanation:

  • Potassium is a very important macronutrient for plants. Its ions cause the turgor movement of guard cells. 
  • The gain of potassium ions by the guard cells causes a decrease in water potential of guard cells. 
  • This makes guard cells turgid and hence they swell. Increase in turgidity of guard cells opens the stomatal pore. 
  • Movement of potassium ions from the guard cells results in the increase of water potential. It becomes flaccid and stomatal pore closes. This mechanism of stomatal opening and closing was first stated by Levitt.

The correct option is B.

According to sugar concentration theory, during daytime guard cells become

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

  1. Turgid

  2. Flaccid

  3. Both A and B

  4. None of these

Show answer
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 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

Show answer
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

Show answer
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

Show answer
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

Show answer
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

Show answer
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'.