- Which of the following is NOT a role of ethylene in plants?
a) Inducing fruit ripening
b) Promoting root initiation
c) Stimulating leaf abscission
d) Promoting lateral bud growth
Answer: d) Promoting lateral bud growth
Explanation:
Ethylene does not promote lateral bud growth. It is involved in processes such as fruit ripening, leaf abscission, and stress responses.
- In which of the following conditions is vernalization most commonly observed?
a) Short-day plants
b) Long-day plants
c) Winter annuals
d) Epiphytes
Answer: c) Winter annuals
Explanation:
Vernalization is commonly observed in winter annuals, such as wheat and cabbage, which require exposure to cold temperatures to trigger flowering in the spring.
- Which of the following plant hormones plays a major role in regulating stress responses such as drought?
a) Auxin
b) Gibberellin
c) Abscisic acid
d) Ethylene
Answer: c) Abscisic acid
Explanation:
Abscisic acid regulates stress responses in plants, such as drought, by promoting stomatal closure to reduce water loss and prevent wilting.
- Which hormone is known to promote leaf senescence?
a) Gibberellin
b) Cytokinin
c) Auxin
d) Ethylene
Answer: d) Ethylene
Explanation:
Ethylene promotes leaf senescence (aging) by accelerating the breakdown of chlorophyll and other cellular components, eventually leading to leaf fall.
- Which plant hormone is known to inhibit root growth at higher concentrations?
a) Auxin
b) Gibberellin
c) Cytokinin
d) Abscisic acid
Answer: a) Auxin
Explanation:
At high concentrations, auxin inhibits root growth, while at lower concentrations, it can promote root formation. This is why auxin must be carefully regulated in plant development.
- Which of the following processes is enhanced by cytokinins?
a) Fruit ripening
b) Root formation
c) Leaf senescence
d) Cell division
Answer: d) Cell division
Explanation:
Cytokinins promote cell division, particularly in the shoot system, and are essential for the growth and development of plant tissues.
- Which plant hormone is used to promote parthenocarpy in fruits?
a) Auxin
b) Cytokinin
c) Gibberellin
d) Abscisic acid
Answer: c) Gibberellin
Explanation:
Gibberellins can induce parthenocarpy, leading to the formation of seedless fruits without fertilization. This is especially useful in commercial fruit production.
- Which of the following hormones is known for delaying senescence in leaves?
a) Auxin
b) Ethylene
c) Cytokinin
d) Gibberellin
Answer: c) Cytokinin
Explanation:
Cytokinins delay leaf senescence by promoting nutrient mobilization and preventing the degradation of chlorophyll and other important cell components.
- Which of the following is the site of synthesis of auxin in plants?
a) Shoot apical meristem
b) Root tips
c) Leaves
d) Flowers
Answer: a) Shoot apical meristem
Explanation:
Auxins are synthesized mainly in the shoot apical meristem, where they regulate growth by promoting cell elongation and inhibiting lateral bud growth (apical dominance).
- Which hormone promotes the development of adventitious roots in stem cuttings?
a) Gibberellin
b) Cytokinin
c) Auxin
d) Ethylene
Answer: c) Auxin
Explanation:
Auxins promote the development of adventitious roots in stem cuttings by stimulating cell division and elongation in the root-forming regions of the cutting
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