- Which of the following processes is controlled by abscisic acid (ABA)?
a) Seed dormancy
b) Fruit ripening
c) Root elongation
d) Photoperiodism
Answer: a) Seed dormancy
Explanation:
Abscisic acid (ABA) induces and maintains seed dormancy, ensuring that seeds do not germinate until conditions are favorable.
- The hormone responsible for breaking seed dormancy is:
a) Abscisic acid
b) Gibberellins
c) Ethylene
d) Cytokinins
Answer: b) Gibberellins
Explanation:
Gibberellins play a key role in breaking seed dormancy by promoting enzyme production that helps convert stored starch into sugar, providing energy for the growing embryo.
- Which of the following is a plant movement in response to gravity?
a) Phototropism
b) Hydrotropism
c) Gravitropism
d) Chemotropism
Answer: c) Gravitropism
Explanation:
Gravitropism (also known as geotropism) is the growth movement of plants in response to gravity. Roots typically show positive gravitropism (growing towards gravity), while shoots show negative gravitropism (growing away from gravity).
- What is the term used for the conversion of a vegetative bud into a flowering bud?
a) Photoperiodism
b) Florigen
c) Vernalization
d) Flower induction
Answer: d) Flower induction
Explanation:
Flower induction is the process by which a vegetative bud transitions into a flowering bud, often influenced by environmental factors such as light and temperature.
- Which plant hormone is involved in the formation of lateral roots?
a) Auxin
b) Cytokinin
c) Gibberellin
d) Ethylene
Answer: a) Auxin
Explanation:
Auxins promote the initiation of lateral roots by stimulating cell division in the pericycle, a tissue layer in the root, leading to the formation of new roots.
- Which of the following plants requires vernalization for flowering?
a) Rice
b) Wheat
c) Tomato
d) Mango
Answer: b) Wheat
Explanation:
Wheat, particularly winter wheat, requires vernalization (exposure to low temperatures) to induce flowering. This ensures that flowering occurs in spring, after the cold winter.
- Which hormone is mainly responsible for the senescence of leaves?
a) Gibberellin
b) Auxin
c) Cytokinin
d) Ethylene
Answer: d) Ethylene
Explanation:
Ethylene accelerates senescence (aging) of leaves, flowers, and fruits by promoting the breakdown of chlorophyll and other cellular components.
- What is the role of phytochromes in plants?
a) Respond to gravity
b) Regulate seed germination
c) Control photoperiodism
d) Induce dormancy
Answer: c) Control photoperiodism
Explanation:
Phytochromes are light-sensitive pigments in plants that play a key role in controlling photoperiodism, which is the response of plants to the length of day and night. This influences flowering and other growth processes.
- Which of the following plant movements is directed by the stimulus of water?
a) Phototropism
b) Gravitropism
c) Hydrotropism
d) Thigmotropism
Answer: c) Hydrotropism
Explanation:
Hydrotropism is the directional growth of plant roots towards water. This helps plants access moisture from the soil more effectively.
- Which hormone plays a significant role in fruit ripening and leaf abscission?
a) Auxin
b) Cytokinin
c) Gibberellin
d) Ethylene
Answer: d) Ethylene
Explanation:
Ethylene is a gaseous hormone that regulates fruit ripening and triggers leaf abscission (the process of leaves detaching from the plant).
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