Plant Hormones — Set 1
Biology · पादप हार्मोन · Questions 1–10 of 50
Which plant hormone is primarily responsible for the phenomenon of apical dominance?
Correct Answer: B. Auxin
Auxin is produced at the shoot tip and inhibits the growth of lateral buds. This process ensures the plant grows taller rather than bushier. It was the first plant hormone to be discovered by scientists.
Which hormone is widely used in agriculture to induce the ripening of fruits?
Correct Answer: B. Ethylene
Ethylene is a gaseous hormone that regulates the fruit ripening process effectively. It breaks down complex sugars into simpler ones to make fruit sweet and soft. Farmers often use it to synchronize the harvest of climacteric fruits.
Which plant hormone acts as a growth inhibitor and helps plants tolerate stressful conditions?
Correct Answer: D. Abscisic Acid
Abscisic Acid (ABA) signals the closure of stomata during severe water scarcity. It helps the plant conserve moisture by preventing excessive transpiration from the leaves. Because of this protective role, it is frequently called the 'stress hormone'.
The rapid elongation of stems, known as 'bolting' in plants like cabbage, is caused by?
Correct Answer: D. Gibberellin
Gibberellins stimulate cell division and elongation specifically in the stem internodes. This hormone can overcome genetic dwarfism in certain varieties of plants. It is also essential for the malting process in the brewing industry.
Which plant hormone promotes cell division and is often found in high concentrations in coconut milk?
Correct Answer: B. Cytokinin
Cytokinins are essential for cytokinesis and delay the aging process in plant leaves. They are synthesized primarily in root tips and transported to developing buds. These hormones work in tandem with auxins to determine plant structure.
Which hormone is responsible for the 'Phototropism' effect, where plants bend toward light?
Correct Answer: C. Auxin
Auxin moves to the shaded side of the stem, causing those cells to grow faster. This uneven growth results in the plant bending toward the light source. Charles Darwin performed early experiments on this specific plant behavior.
Which hormone is used to produce seedless fruits through the process of parthenocarpy?
Correct Answer: C. Gibberellin
Gibberellins can induce fruit development without the need for fertilization. This results in the production of seedless varieties of grapes and watermelons. It is a common practice in modern commercial horticulture.
Which substance is used to delay the wilting of flowers and yellowing of leafy vegetables?
Correct Answer: C. Cytokinin
Cytokinins delay senescence by preventing the degradation of proteins and chlorophyll. Applying this hormone can keep cut flowers fresh for a longer period. It helps maintain the nutrient balance within the plant tissues.
Which plant hormone is synthesized in response to wounding and pathogenic attacks?
Correct Answer: D. Ethylene
Ethylene production increases significantly when a plant part is physically damaged. It acts as a signal to initiate defense mechanisms against pests and diseases. This gaseous hormone can also spread the signal to neighboring plants.
Which hormone is primarily responsible for maintaining seed dormancy during winter?
Correct Answer: B. Abscisic Acid
Abscisic Acid prevents the seed from germinating until environmental conditions are favorable. It inhibits the growth-promoting effects of other hormones like gibberellins. This mechanism ensures that seeds survive cold or dry seasons.