Here below some basic MCQ’s of plant growth and developement with answer which is explained in details. Let’s check one by one which is given below.
- Which of the following hormones promotes cell division in plants?
a) Abscisic acid
b) Gibberellins
c) Cytokinins
d) Ethylene
Answer: c) Cytokinins
Explanation:
Cytokinins are plant hormones that promote cell division (cytokinesis) in plant roots and shoots. They also influence the growth of shoot buds and delay the aging of leaves.
- Which phase of growth is characterized by slow growth at the beginning and end, with rapid growth in between?
a) Exponential phase
b) Lag phase
c) Stationary phase
d) Log phase
Answer: a) Exponential phase
Explanation:
The exponential phase (also known as the log phase) represents the period of rapid growth, where cells divide at an exponential rate. In the S-shaped sigmoid growth curve, this phase is observed between the lag phase (slow growth at the beginning) and the stationary phase (slowing down towards the end).
- Vernalization is required for which of the following?
a) Seed dormancy
b) Induction of flowering
c) Fruit ripening
d) Apical dominance
Answer: b) Induction of flowering
Explanation:
Vernalization is the process of inducing flowering in plants by exposing them to prolonged cold temperatures. This treatment helps certain plants flower in spring after a cold winter.
- Which of the following is NOT a plant growth regulator?
a) Ethylene
b) Auxin
c) Gibberellin
d) Glucose
Answer: d) Glucose
Explanation:
Glucose is not a plant hormone but a product of photosynthesis. Ethylene, auxin, and gibberellin are all plant growth regulators that play a role in various developmental processes in plants.
- Photoperiodism is the response of plants to:
a) Temperature changes
b) Day and night length
c) Soil moisture
d) Atmospheric pressure
Answer: b) Day and night length
Explanation:
Photoperiodism is the physiological reaction of organisms to the length of day or night. In plants, it influences processes like flowering, with some plants being short-day plants, long-day plants, or day-neutral.
- Which plant hormone is known as the “stress hormone”?
a) Auxin
b) Abscisic acid
c) Gibberellin
d) Cytokinin
Answer: b) Abscisic acid
Explanation:
Abscisic acid (ABA) is called the stress hormone because it plays a key role in helping plants respond to environmental stress, particularly drought, by inducing stomatal closure to conserve water.
- What is the primary effect of auxins in plants?
a) Promote fruit ripening
b) Inhibit seed germination
c) Stimulate stem elongation
d) Delay leaf senescence
Answer: c) Stimulate stem elongation
Explanation:
Auxins are primarily involved in promoting cell elongation, especially in the stems, and are responsible for phototropism and gravitropism, helping the plant grow towards light and against gravity.
- Which of the following is required for the synthesis of gibberellins in plants?
a) Light
b) Nitrogen
c) Phosphorus
d) Water
Answer: a) Light
Explanation:
Light is an important environmental factor for the synthesis of gibberellins, which play a key role in seed germination, stem elongation, and flowering.
- Which plant hormone is associated with the ripening of fruits?
a) Gibberellin
b) Auxin
c) Ethylene
d) Cytokinin
Answer: c) Ethylene
Explanation:
Ethylene is a gaseous plant hormone that regulates the ripening of fruits. It also plays a role in leaf abscission and flower senescence.
- The process of seed germination is initiated by:
a) Ethylene
b) Gibberellins
c) Abscisic acid
d) Cytokinins
Answer: b) Gibberellins
Explanation:
Gibberellins are crucial in breaking seed dormancy and initiating germination by promoting the synthesis of enzymes that digest stored food in the seed, making energy available for growth.
- Which hormone is responsible for apical dominance in plants?
a) Ethylene
b) Gibberellins
c) Auxins
d) Abscisic acid
Answer: c) Auxins
Explanation:
Auxins produced in the apical meristem inhibit the growth of lateral buds, a phenomenon known as apical dominance. This ensures the plant grows taller rather than wider.
- Which type of movement is exhibited by plants in response to light?
a) Hydrotropism
b) Thigmotropism
c) Phototropism
d) Gravitropism
Answer: c) Phototropism
Explanation:
Phototropism is the growth movement of plants in response to light. Auxins accumulate on the shaded side of the plant, causing cell elongation and bending the plant towards the light.
- Which of the following hormones is responsible for the closing of stomata during water stress?
a) Abscisic acid
b) Cytokinins
c) Gibberellins
d) Ethylene
Answer: a) Abscisic acid
Explanation:
Abscisic acid (ABA) plays a key role in closing stomata during water stress to prevent excessive water loss through transpiration.
- The phenomenon of bolting in plants is induced by:
a) Ethylene
b) Gibberellins
c) Auxins
d) Cytokinins
Answer: b) Gibberellins
Explanation:
Bolting refers to the rapid elongation of the floral stalk, which is often induced by gibberellins, particularly in plants like cabbage and lettuce.
- Which of the following is an effect of cytokinins?
a) Delaying leaf senescence
b) Promoting fruit ripening
c) Inducing seed dormancy
d) Inhibiting stem elongation
Answer: a) Delaying leaf senescence
Explanation:
Cytokinins delay leaf senescence (aging) by promoting nutrient mobilization and helping maintain chlorophyll content, thereby prolonging the green life of the leaf.
- The maximum elongation in a plant cell occurs during which phase of growth?
a) Cell division phase
b) Maturation phase
c) Cell enlargement phase
d) Differentiation phase
Answer: c) Cell enlargement phase
Explanation:
During the cell enlargement phase, cells increase in size due to the uptake of water, which leads to cell elongation. This phase follows the cell division phase in the growth process.
- Which of the following is a synthetic auxin?
a) NAA (Naphthalene acetic acid)
b) IAA (Indole-3-acetic acid)
c) GA3 (Gibberellic acid)
d) Zeatin
Answer: a) NAA (Naphthalene acetic acid)
Explanation:
NAA (Naphthalene acetic acid) is a synthetic auxin that is used in agriculture to promote root initiation in cuttings and tissue culture.
- In which of the following plants is photoperiodism most evident?
a) Mango
b) Wheat
c) Tomato
d) Rice
Answer: b) Wheat
Explanation:
Wheat is a long-day plant, meaning it requires longer daylight hours to induce flowering. Photoperiodism is the response of plants to the length of day and night.
- What is the name of the process by which a seed becomes dormant?
a) Imbibition
b) Stratification
c) Quiescence
d) Vernalization
Answer: c) Quiescence
Explanation:
Quiescence refers to a state of dormancy where the seed is viable but does not germinate due to unfavorable environmental conditions, such as lack of water or appropriate temperature.
- What is the function of the hormone gibberellin in seed germination?
a) It breaks down starch into sugar.
b) It closes stomata to prevent water loss.
c) It delays the aging of leaves.
d) It inhibits seed germination.
Answer: a) It breaks down starch into sugar.
Explanation:
Gibberellins promote the synthesis of the enzyme amylase, which breaks down stored starch into sugars, providing energy for the growth of the embryo during seed germination.
- 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).
- 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.
- Which of the following is an example of a long-day plant?
a) Tomato
b) Rice
c) Wheat
d) Sunflower
Answer: c) Wheat
Explanation:
Long-day plants, like wheat, flower when they are exposed to longer daylight hours, typically more than 12 hours a day. These plants are often found in regions where the days are longer during certain seasons.
- Which of the following plant hormones induces the formation of adventitious roots in cuttings?
a) Gibberellin
b) Ethylene
c) Cytokinin
d) Auxin
Answer: d) Auxin
Explanation:
Auxins promote the formation of adventitious roots in cuttings by stimulating cell division and elongation. This property of auxins is widely used in plant propagation through cuttings.
- Which process describes the falling off of leaves, flowers, or fruits from a plant?
a) Apical dominance
b) Abscission
c) Bolting
d) Photoperiodism
Answer: b) Abscission
Explanation:
Abscission is the process in which plants shed leaves, flowers, or fruits. Ethylene promotes abscission by weakening the cells at the abscission zone, leading to the detachment of plant organs.
- Which of the following is a naturally occurring auxin?
a) NAA (Naphthalene acetic acid)
b) IBA (Indole-3-butyric acid)
c) 2,4-D (2,4-Dichlorophenoxyacetic acid)
d) IAA (Indole-3-acetic acid)
Answer: d) IAA (Indole-3-acetic acid)
Explanation:
IAA (Indole-3-acetic acid) is a naturally occurring auxin that plays a vital role in plant growth and development by regulating cell elongation, apical dominance, and root initiation.
- What is the primary role of gibberellins in plants?
a) Inhibits seed germination
b) Delays senescence
c) Promotes stem elongation
d) Closes stomata
Answer: c) Promotes stem elongation
Explanation:
Gibberellins promote cell elongation and division in the stems, leading to increased plant height. They are also involved in breaking seed dormancy and inducing flowering.
- Which of the following is an effect of cytokinins?
a) Promote root growth
b) Delay leaf senescence
c) Promote fruit ripening
d) Stimulate stem elongation
Answer: b) Delay leaf senescence
Explanation:
Cytokinins delay leaf senescence by promoting nutrient mobilization, thereby maintaining the green color and health of leaves for a longer period.
- Which of the following plant growth regulators is involved in seed dormancy and closing of stomata under water stress?
a) Auxin
b) Abscisic acid
c) Ethylene
d) Gibberellin
Answer: b) Abscisic acid
Explanation:
Abscisic acid (ABA) induces seed dormancy and plays a significant role in closing stomata during water stress, helping plants conserve water by reducing transpiration.
- Which of the following is responsible for the upward growth of shoots in plants?
a) Positive phototropism
b) Positive gravitropism
c) Negative gravitropism
d) Hydrotropism
Answer: c) Negative gravitropism
Explanation:
Negative gravitropism is the growth movement of shoots away from the force of gravity, causing them to grow upward. In contrast, roots show positive gravitropism as they grow towards gravity.
- Which plant hormone is known to promote flowering in pineapple and other plants?
a) Auxin
b) Gibberellin
c) Cytokinin
d) Ethylene
Answer: d) Ethylene
Explanation:
Ethylene promotes flowering in certain plants, such as pineapple. It is also involved in fruit ripening and leaf abscission.
- What is the role of cytokinins in plant growth?
a) Promote seed germination
b) Delay leaf senescence
c) Induce flowering
d) Promote fruit ripening
Answer: b) Delay leaf senescence
Explanation:
Cytokinins delay leaf senescence (aging) by promoting cell division and nutrient distribution, ensuring the leaves retain their green color and functionality for longer.
- Which of the following plants shows a short-day photoperiodic response for flowering?
a) Wheat
b) Rice
c) Lettuce
d) Barley
Answer: b) Rice
Explanation:
Rice is a short-day plant, meaning it flowers when the length of the day is shorter than a critical duration. Short-day plants typically bloom in the late summer or fall when the days are shorter.
- Which plant hormone is used to promote rooting in plant cuttings?
a) Cytokinin
b) Auxin
c) Ethylene
d) Gibberellin
Answer: b) Auxin
Explanation:
Auxins, particularly synthetic forms like IBA (Indole-3-butyric acid), are commonly used in horticulture to promote root formation in plant cuttings.
- Which of the following hormones inhibits seed germination and growth during unfavorable conditions?
a) Auxin
b) Abscisic acid
c) Ethylene
d) Cytokinin
Answer: b) Abscisic acid
Explanation:
Abscisic acid (ABA) inhibits seed germination and growth under unfavorable conditions, such as drought, by inducing dormancy and closing stomata to conserve water.
- Which hormone plays a significant role in controlling stomatal closure during drought?
a) Auxin
b) Gibberellin
c) Ethylene
d) Abscisic acid
Answer: d) Abscisic acid
Explanation:
Abscisic acid (ABA) triggers the closing of stomata during drought or water stress, reducing water loss through transpiration and helping the plant conserve water.
- Vernalization is essential for which type of plants?
a) Biennial plants
b) Short-day plants
c) Perennial plants
d) Day-neutral plants
Answer: a) Biennial plants
Explanation:
Vernalization is the exposure of biennial plants (such as winter wheat and cabbage) to cold temperatures to induce flowering in their second year of growth.
- Which hormone is responsible for the initiation of flowering in long-day plants?
a) Ethylene
b) Cytokinin
c) Auxin
d) Gibberellin
Answer: d) Gibberellin
Explanation:
Gibberellins promote flowering in long-day plants by stimulating the growth and elongation of floral stalks, allowing the plants to flower in response to longer daylight hours.
- Which of the following promotes seed germination by stimulating the production of hydrolytic enzymes?
a) Ethylene
b) Gibberellins
c) Cytokinins
d) Auxins
Answer: b) Gibberellins
Explanation:
Gibberellins stimulate the production of hydrolytic enzymes, such as amylase, which break down stored starch into sugars, providing energy for seed germination.
- Which plant hormone is responsible for fruit ripening and also promotes abscission of leaves?
a) Gibberellin
b) Cytokinin
c) Auxin
d) Ethylene
Answer: d) Ethylene
Explanation:
Ethylene is responsible for accelerating fruit ripening and also promotes the abscission of leaves, flowers, and fruits by weakening the cell walls in the abscission zone.
- What is the effect of auxins on apical dominance?
a) Inhibit apical dominance
b) Promote lateral bud growth
c) Promote apical dominance
d) Induce senescence
Answer: c) Promote apical dominance
Explanation:
Auxins promote apical dominance by inhibiting the growth of lateral buds, allowing the apical bud to grow more vigorously and maintain the plant’s vertical growth.
- Which hormone promotes the formation of adventitious roots on cuttings?
a) Cytokinins
b) Ethylene
c) Auxins
d) Gibberellins
Answer: c) Auxins
Explanation:
Auxins are widely used to promote the formation of adventitious roots on plant cuttings, aiding in plant propagation.
- Which of the following hormones is mainly responsible for the elongation of internodes in plants?
a) Cytokinin
b) Gibberellin
c) Abscisic acid
d) Auxin
Answer: b) Gibberellin
Explanation:
Gibberellins promote internodal elongation by stimulating cell elongation and division, which leads to taller plants with longer stems.
- The role of cytokinin in plant tissue culture is to:
a) Promote root formation
b) Promote shoot formation
c) Inhibit cell division
d) Induce dormancy
Answer: b) Promote shoot formation
Explanation:
In plant tissue culture, cytokinins are used to promote shoot formation by stimulating cell division and shoot bud differentiation.
- Which of the following is a short-day plant?
a) Wheat
b) Tobacco
c) Potato
d) Radish
Answer: b) Tobacco
Explanation:
Tobacco is a short-day plant that requires shorter daylight hours to initiate flowering. Such plants bloom when the length of the day is shorter than a critical duration.
- Which hormone is commonly used to break seed dormancy and promote germination?
a) Abscisic acid
b) Cytokinin
c) Gibberellin
d) Auxin
Answer: c) Gibberellin
Explanation:
Gibberellins promote seed germination by breaking seed dormancy and stimulating the production of enzymes that break down stored food in seeds.
- Which of the following is a climactic response in plants?
a) Vernalization
b) Thigmotropism
c) Hydrotropism
d) Gravitropism
Answer: b) Thigmotropism
Explanation:
Thigmotropism is the directional growth response of plants to touch stimuli, as seen in tendrils of climbing plants that wrap around structures for support.
- Which hormone is involved in closing stomata during water stress in plants?
a) Auxin
b) Abscisic acid
c) Gibberellin
d) Ethylene
Answer: b) Abscisic acid
Explanation:
Abscisic acid (ABA) helps close the stomata during water stress, preventing water loss through transpiration and conserving water within the plant.
- What is the major role of ethylene in fruit physiology?
a) Inhibit ripening
b) Promote fruit ripening
c) Stimulate seed dormancy
d) Delay senescence
Answer: b) Promote fruit ripening
Explanation:
Ethylene is a gaseous hormone that promotes the ripening of fruits by regulating various physiological processes, including the breakdown of cell walls and the conversion of starches to sugars.
- Which of the following factors can break seed dormancy?
a) Light exposure
b) High temperature
c) Gibberellins
d) Abscisic acid
Answer: c) Gibberellins
Explanation:
Gibberellins can break seed dormancy by promoting the synthesis of enzymes that degrade stored food reserves, providing energy for the seedling’s growth.
- Which of the following is not an effect of abscisic acid?
a) Inducing dormancy
b) Promoting senescence
c) Promoting stomatal closure
d) Stimulating seed germination
Answer: d) Stimulating seed germination
Explanation:
Abscisic acid inhibits seed germination and promotes seed dormancy, particularly during unfavorable conditions. It does not stimulate germination.
- Which plant hormone is known to cause apical dominance, inhibiting the growth of lateral buds?
a) Gibberellin
b) Cytokinin
c) Auxin
d) Abscisic acid
Answer: c) Auxin
Explanation:
Auxin maintains apical dominance by inhibiting the growth of lateral buds, allowing the apical bud to grow more vigorously and dominate the plant’s growth pattern.
- Which process is controlled by vernalization in plants?
a) Seed germination
b) Leaf abscission
c) Induction of flowering
d) Root elongation
Answer: c) Induction of flowering
Explanation:
Vernalization is the process in which prolonged exposure to cold temperatures induces flowering in plants, particularly in biennials and winter annuals.
- Which of the following is an effect of cytokinins on plants?
a) Promote cell division
b) Inhibit root growth
c) Promote fruit ripening
d) Stimulate seed dormancy
Answer: a) Promote cell division
Explanation:
Cytokinins promote cell division and are essential for tissue growth and development, particularly in the shoot system.
- Which plant hormone helps in overcoming apical dominance, promoting lateral bud growth?
a) Gibberellin
b) Ethylene
c) Cytokinin
d) Abscisic acid
Answer: c) Cytokinin
Explanation:
Cytokinins promote lateral bud growth by overcoming the inhibitory effect of auxins, thereby reducing apical dominance and encouraging the development of side shoots.
- Which of the following is not a function of auxin?
a) Promoting root initiation
b) Promoting stem elongation
c) Inducing seed dormancy
d) Inhibiting lateral bud growth
Answer: c) Inducing seed dormancy
Explanation:
Auxins promote stem elongation, root initiation, and inhibit lateral bud growth (apical dominance). However, they do not induce seed dormancy; this is primarily a function of abscisic acid.
- Which of the following is an example of a long-day plant?
a) Radish
b) Tobacco
c) Lettuce
d) Rice
Answer: c) Lettuce
Explanation:
Lettuce is a long-day plant that requires longer daylight hours to initiate flowering. These plants usually flower in late spring or early summer when the days are longer.
- Gibberellins are used in the brewing industry to:
a) Stimulate root growth
b) Increase seed germination
c) Promote sugar accumulation in grains
d) Stimulate production of hydrolytic enzymes
Answer: d) Stimulate production of hydrolytic enzymes
Explanation:
In the brewing industry, gibberellins are used to stimulate the production of hydrolytic enzymes like amylase, which break down starch into fermentable sugars during the malting process.
- Which hormone is responsible for the closing of stomata during drought conditions?
a) Gibberellin
b) Auxin
c) Ethylene
d) Abscisic acid
Answer: d) Abscisic acid
Explanation:
Abscisic acid (ABA) is responsible for closing stomata during drought conditions, reducing water loss through transpiration and conserving moisture within the plant.
- Which of the following is a role of ethylene in plant growth?
a) Promote lateral bud growth
b) Delay fruit ripening
c) Promote stem elongation
d) Promote fruit ripening
Answer: d) Promote fruit ripening
Explanation:
Ethylene promotes fruit ripening by regulating various biochemical processes, such as the conversion of starches to sugars, softening of the fruit, and color change.
- Which hormone is used to induce parthenocarpy in plants?
a) Abscisic acid
b) Gibberellin
c) Ethylene
d) Cytokinin
Answer: b) Gibberellin
Explanation:
Gibberellins can induce parthenocarpy, leading to the development of seedless fruits without fertilization. This is commonly applied in crops like grapes and tomatoes.
- Which hormone is primarily responsible for inhibiting seed germination during unfavorable conditions?
a) Gibberellin
b) Auxin
c) Abscisic acid
d) Cytokinin
Answer: c) Abscisic acid
Explanation:
Abscisic acid (ABA) inhibits seed germination by inducing seed dormancy during unfavorable conditions, such as drought, ensuring the seed remains viable until conditions improve.
- 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.
- 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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