Tag: chemical coordination in plants

Questions Related to chemical coordination in plants

During drought, plants develop hormone

biology chemical coordination in plants abscisic acid fruit plants: structure and function

  1. Indole acetic acid

  2. Naphthalene acetic acid

  3. Indolebutyric acid

  4. Abscisic acid

  5. Ethylene

Show answer
Correct Option: D
Explanation:

Stress hormone is a hormone produced during adverse environmental conditions. Abscisic acid (ABA) is called as stress hormone. Due to this hormone, plants respond to stresses conditions like cold, drought. It increases the tolerance of plants toward various stresses. It is found in high concentration in roots during drought and later translocated to leaves. It causes stomatal closure during water stress. It also promotes seed dormancy under adverse condition.

Thus, the correct answer is option D.

Which one is wrongly matched?

biology chemical coordination in plants abscisic acid fruit plants: structure and function

  1. Auxins - to grow

  2. Gibberellins - Gibberella fujikuroi

  3. Cytokinins - Herring sperm DNA

  4. ABA - flowering hormone

  5. Ethylene - gas hormone

Show answer
Correct Option: D
Explanation:

Auxin is a plant hormone that is involved in growth and development of plant. Kinetin, a type of cytokinin was isolated from autoclaved herring sperm DNA by Miller and Skoog. Gibberellin hormone was first isolated from fungus Gibberella fujikuroi. Ethylene is a gaseous hormone which helps in ripening process and hence also called as ripening hormone. ABA is responsible for abscission of leaves, fruits and flowers. Florigen is a flowering hormone that is responsible for flowering in certain plants.

Thus, the correct answer is option D.

Leaf abscission is brought about by

biology chemical coordination in plants abscisic acid fruit plants: structure and function

  1. Auxin

  2. Cytokinin

  3. Gibberellin

  4. ABA

Show answer
Correct Option: D
Explanation:

Leaf abscission is a detachment or fall of older leaves.It occurs at the base of the petiole. During abscission, high synthesize of abscisic acid is observed along with decrease in the concentration of auxin. ABA loosens the cell wall and cells separate which ultimately leads to leaf abscission. 

Thus, the correct answer is option D.

Hormone antagonistic to ABA is

biology chemical coordination in plants abscisic acid fruit plants: structure and function

  1. Gibberellin

  2. Auxin

  3. Ethylene

  4. Cytokinin

Show answer
Correct Option: A
Explanation:

Abscisic acid is a plant hormone. It causes abscission of leaves. It induces dormancy of seed under unfavorable condition. Gibberellin is a plant hormone that is an antagonist to the abscisic acid hormone. It regulates plant growth. It stimulates stem elongation, germination, flowering. it breaks the seed dormancy and initiates germination process. 

Thus, the correct answer is option A.

Which one demonstrates process associated with abscission of a leaf?

biology chemical coordination in plants abscisic acid fruit plants: structure and function

  1. In the leaf concentration of both auxin and ABA decreases

  2. In the leaf concentration of both auxin and ABA increases

  3. Reduction in ABA concentration and increase of auxin concentration in the leaf

  4. Reduction in concentration of auxin and increase of concentration of ABA in the leaf

Show answer
Correct Option: D
Explanation:
Auxin is a plant hormone which prevents the abscission of leaves and fruits. Young leaves and fruits produce auxin and thus remain attached to the stem. When the level of auxin declines in leaves, leaves the drop. ABA induces abscission of leaves. Hence, during abscission of a leaf, there is the reduction in auxin concentration and increase in ABA concentration in the leaf.
Thus, the correct answer is option D.

Hormone antagonist to gibberellins is

biology chemical coordination in plants abscisic acid fruit plants: structure and function

  1. IAA

  2. ABA

  3. Zeatin

  4. Ethylene

Show answer
Correct Option: B
Explanation:
Gibberellin or Gibberellic Acid (GA) is produced in embryos, roots, and young leaves and it enhances growth. Abscisic acid is a naturally occurring growth inhibitor found in wide variety of plants, synthesised in leaves. Gibberellin delays senescence in plants. Abscisic acid promotes the senescence of leaf, i.e., fall of leaves happens due to abscisic acid. Gibberellin breaks dormancy of seeds and as opposed to Abscisic acid, which induces dormancy of buds and seeds.
Hence, due to their opposite effect on plant growth, Gibberellins and Abscisic acid can be said to be an antagonist to each other.
So, the correct answer is 'ABA'

Choose the correct answer from the alternatives given.
Which of the following statements is false?

biology chemical coordination in plants abscisic acid fruit plants: structure and function

  1. Auxins and gibberellins promote stem elongation.

  2. Cytokinins promote cell division but retard leaf ageing

  3. Abscisic acid promotes water loss and dormancy

  4. Ethylene promotes fruit ripening and abscission

Show answer
Correct Option: C
Explanation:

ABA helps seeds to withstand desiccation and other factors unfavorable for growth.

So, the correct option is 'Abscisic acid promotes water loss and dormancy'.

Choose the correct answer from the alternatives given.
Which of the following plant hormones is called the stress hormone because it produces dormancy in seeds and buds?

biology chemical coordination in plants abscisic acid fruit plants: structure and function

  1. Abscisic acid

  2. Auxin

  3. Cytokinin

  4. Ethylene

Show answer
Correct Option: A
Explanation:

Abscisic acid inhibits seed germination and stimulates the closure of stomata in the epidermis and increases the tolerance of plants to various kinds of stresses. Therefore, it is also called the stress hormone.

So, the correct option is 'Abscisic acid'. 

Choose the correct answer from the alternatives given.
Abscisic acid is derived from

biology chemical coordination in plants abscisic acid fruit plants: structure and function

  1. carotene

  2. methionine

  3. ethylene

  4. amatene

Show answer
Correct Option: A
Explanation:

The C15 backbone of ABA is formed after cleavage of C40 Carotenoids.

So, the correct option is 'Carotene'.

Seed dormancy is caused by ______________.

biology chemical coordination in plants abscisic acid fruit plants: structure and function

  1. $C _2H _4$

  2. ABA

  3. IAA

  4. $GA _3$.

Show answer
Correct Option: B
Explanation:

Seed dormancy is mainly caused by ABA. Dormancy allows seeds to tolerate desiccation and extremes of temperature better. Due to its action of inducing dormancy in seeds, buds etc. ABA is also called as dormin.