- The rapid growth of the floral stalk during the flowering stage is termed as:
a) Bolting
b) Vernalization
c) Abscission
d) Phototropism
Answer: a) Bolting
Explanation:
Bolting refers to the rapid elongation of the flowering stem, particularly in plants like cabbage, lettuce, and spinach. This process is often induced by gibberellins.
- Which of the following is the function of florigen?
a) Initiation of seed germination
b) Regulation of leaf fall
c) Induction of flowering
d) Inhibition of fruit ripening
Answer: c) Induction of flowering
Explanation:
Florigen is a hypothetical plant hormone responsible for inducing flowering in plants. It is believed to be produced in leaves in response to photoperiodic signals and transported to the shoot apical meristem.
- Which hormone is associated with the promotion of parthenocarpy (development of seedless fruits)?
a) Gibberellin
b) Ethylene
c) Auxin
d) Cytokinin
Answer: a) Gibberellin
Explanation:
Gibberellins can induce parthenocarpy, which is the development of fruits without fertilization, leading to seedless varieties. This is commonly observed in crops like grapes and tomatoes.
- The hormone responsible for apical dominance, where the main central stem of the plant grows more vigorously than side stems, is:
a) Gibberellin
b) Auxin
c) Ethylene
d) Cytokinin
Answer: b) Auxin
Explanation:
Auxins are produced in the apical bud (tip of the shoot) and suppress the growth of lateral (side) buds, promoting apical dominance and vertical growth.
- The phenomenon in which plants open their flowers during the day and close them at night is called:
a) Nyctinasty
b) Photoperiodism
c) Gravitropism
d) Phototropism
Answer: a) Nyctinasty
Explanation:
Nyctinasty refers to the movement of plant organs (such as leaves or flowers) in response to the onset of darkness, typically closing at night and reopening during the day. It is regulated by circadian rhythms and environmental light conditions.
- Which hormone is responsible for the delay in the senescence of leaves and fruits?
a) Cytokinin
b) Auxin
c) Ethylene
d) Abscisic acid
Answer: a) Cytokinin
Explanation:
Cytokinins delay senescence (aging) by promoting cell division and nutrient mobilization, helping the plant maintain its green color and functionality for a longer time.
- Which of the following is an effect of abscisic acid (ABA)?
a) Promotes seed germination
b) Induces dormancy in seeds
c) Delays fruit ripening
d) Enhances phototropism
Answer: b) Induces dormancy in seeds
Explanation:
Abscisic acid (ABA) induces and maintains seed dormancy, ensuring that seeds do not germinate prematurely under unfavorable conditions.
- Which of the following movements is caused by touch stimuli?
a) Phototropism
b) Thigmotropism
c) Gravitropism
d) Hydrotropism
Answer: b) Thigmotropism
Explanation:
Thigmotropism is the movement of plants in response to mechanical stimuli like touch. This is commonly observed in climbing plants, where tendrils wrap around objects for support.
- Vernalization can be defined as:
a) The requirement of light for seed germination
b) The process of exposing plants to cold temperatures to induce flowering
c) The upward movement of water in plants
d) The growth response to gravity
Answer: b) The process of exposing plants to cold temperatures to induce flowering
Explanation:
Vernalization is the process where prolonged exposure to cold temperatures induces flowering in certain plants, such as winter cereals and biennial crops.
- Which plant hormone is primarily involved in controlling cell elongation in stems and is responsible for phototropism?
a) Cytokinin
b) Gibberellin
c) Auxin
d) Abscisic acid
Answer: c) Auxin
Explanation:
Auxin regulates cell elongation, especially in stems, and is responsible for phototropism, where the plant bends toward light by elongating the cells on the shaded side.
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