- Photoperiodism in plants is controlled by which pigment?
a) Chlorophyll
b) Carotenoid
c) Phytochrome
d) Anthocyanin
Answer: c) Phytochrome
Explanation:
Phytochrome is a light-sensitive pigment that regulates photoperiodism in plants, enabling them to respond to the length of day and night to time flowering and other developmental processes.
- Which of the following plant responses is triggered by light?
a) Gravitropism
b) Phototropism
c) Hydrotropism
d) Thigmotropism
Answer: b) Phototropism
Explanation:
Phototropism is the directional growth of plants in response to light. Shoots usually exhibit positive phototropism, growing toward the light source.
- Which of the following plant hormones is responsible for bolting in plants like cabbage?
a) Auxin
b) Gibberellin
c) Ethylene
d) Cytokinin
Answer: b) Gibberellin
Explanation:
Gibberellins promote bolting, which is the rapid elongation of the floral stalk in plants like cabbage, particularly under long-day conditions.
- Which hormone helps to induce seed dormancy in plants?
a) Auxin
b) Gibberellin
c) Cytokinin
d) Abscisic acid
Answer: d) Abscisic acid
Explanation:
Abscisic acid induces seed dormancy and inhibits germination under unfavorable conditions, ensuring seeds remain dormant until conditions are suitable for growth.
- Which of the following processes is controlled by gibberellins?
a) Stomatal closure
b) Leaf senescence
c) Fruit ripening
d) Seed germination
Answer: d) Seed germination
Explanation:
Gibberellins stimulate seed germination by promoting the synthesis of enzymes that break down stored food reserves, providing energy for the growing seedling.
- Vernalization is a process that:
a) Inhibits flowering in short-day plants
b) Stimulates flowering after a cold period
c) Promotes seed dormancy
d) Prevents fruit ripening
Answer: b) Stimulates flowering after a cold period
Explanation:
Vernalization is the induction of flowering following exposure to prolonged cold temperatures. This is essential for certain plants to flower in the spring.
- Which of the following plant hormones is a gas?
a) Auxin
b) Cytokinin
c) Gibberellin
d) Ethylene
Answer: d) Ethylene
Explanation:
Ethylene is a gaseous plant hormone that regulates processes such as fruit ripening, leaf abscission, and the response to stress conditions.
- Which hormone promotes the ripening of climacteric fruits?
a) Cytokinin
b) Abscisic acid
c) Gibberellin
d) Ethylene
Answer: d) Ethylene
Explanation:
Ethylene promotes the ripening of climacteric fruits like bananas, apples, and tomatoes by enhancing respiration and other ripening processes.
- Which hormone is involved in promoting apical dominance in plants?
a) Abscisic acid
b) Auxin
c) Gibberellin
d) Cytokinin
Answer: b) Auxin
Explanation:
Auxin maintains apical dominance by inhibiting the growth of lateral buds and ensuring that the apical bud remains the dominant growing point in the plant.
- Which hormone is responsible for inducing seed germination in barley seeds during malting?
a) Abscisic acid
b) Gibberellin
c) Ethylene
d) Cytokinin
Answer: b) Gibberellin
Explanation:
Gibberellins induce seed germination by stimulating the synthesis of enzymes, such as amylase, that convert stored starch into sugar during the malting process in barley.
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