Plant Hormones Practice Questions
17 free Plant Hormones practice questions for the General Science. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
What are plant hormones commonly called?
- A Phytochromes
- B Secondary metabolites
- C Phytoalexins
- D Phytohormones
Correct answer: Phytohormones
Plant hormones are also known as phytohormones. They are chemical messengers that regulate plant growth, development, and responses to environmental stimuli.
Which hormone is responsible for cell division in plants?
- A Auxin
- B Gibberellin
- C Cytokinin
- D Ethylene
Correct answer: Cytokinin
Cytokinins stimulate cell division and promote the growth of lateral buds. They help delay leaf aging and work together with auxins in plant development.
Which plant hormone promotes stem elongation and seed germination?
- A Ethylene
- B Auxin
- C Gibberellin
- D Abscisic acid
Correct answer: Gibberellin
Gibberellins promote stem elongation, seed germination, and flowering in some plants. They play an important role in breaking seed dormancy.
Which plant hormone is responsible for fruit ripening?
- A Auxin
- B Cytokinin
- C Gibberellin
- D Ethylene
Correct answer: Ethylene
Ethylene is a gaseous plant hormone that regulates fruit ripening. It accelerates processes such as softening, color change, and sugar accumulation.
Which hormone helps in delaying the aging of plant leaves?
- A Cytokinin
- B Ethylene
- C Auxin
- D Abscisic acid
Correct answer: Cytokinin
Cytokinins delay senescence or aging in plant leaves. They maintain chlorophyll levels and prolong leaf life.
Which plant hormone is mainly produced in the root tips?
- A Auxin
- B Cytokinin
- C Ethylene
- D Gibberellin
Correct answer: Cytokinin
Cytokinins are synthesized mainly in root tips and transported to other parts of the plant. They promote cell division and shoot formation.
Which plant hormone helps plants respond to gravity?
- A Auxin
- B Ethylene
- C Gibberellin
- D Cytokinin
Correct answer: Auxin
Auxin distribution in plant tissues enables plants to respond to gravity, a phenomenon known as gravitropism. It causes differential growth in roots and shoots.
Which plant hormone inhibits plant growth and induces dormancy?
- A Gibberellin
- B Brassinosteroid
- C Abscisic acid
- D Ethylene
Correct answer: Abscisic acid
Abscisic acid inhibits growth and induces dormancy in seeds and buds. It helps plants survive unfavorable environmental conditions.
Which hormone is involved in phototropism in plants?
- A Auxin
- B Cytokinin
- C Ethylene
- D Gibberellin
Correct answer: Auxin
Auxin plays a key role in phototropism, the bending of plants toward light. It accumulates on the shaded side of stems, causing cells to elongate.
Which plant hormone can trigger flowering in long-day plants even when they are kept under short-day conditions?
- A Gibberellin
- B Abscisic acid
- C Ethylene
- D Auxin
Correct answer: Gibberellin
Applying gibberellins substitutes for the long-day light stimulus, causing bolting and flowering in long-day plants such as cabbage and spinach. Gibberellins also promote stem elongation and seed germination.
Which hormone promotes lateral bud growth when auxin levels decrease?
- A Cytokinin
- B Ethylene
- C Abscisic acid
- D Gibberellin
Correct answer: Cytokinin
Cytokinins stimulate the growth of lateral buds when auxin levels drop. This interaction controls apical dominance in plants.
Which plant hormone is unique because it exists as a gas?
- A Auxin
- B Ethylene
- C Cytokinin
- D Gibberellin
Correct answer: Ethylene
Ethylene is the only gaseous plant hormone. It diffuses easily through plant tissues and regulates fruit ripening and leaf fall.
Which hormone helps plants close their stomata during water stress?
- A Salicylic acid
- B Ethylene
- C Abscisic acid
- D Cytokinin
Correct answer: Abscisic acid
Abscisic acid signals guard cells to close stomata during drought. This reduces water loss through transpiration.
Which hormone is most associated with apical dominance?
- A Auxin
- B Cytokinin
- C Ethylene
- D Gibberellin
Correct answer: Auxin
Auxin produced in the apical bud suppresses the growth of lateral buds. This phenomenon is known as apical dominance.
Which hormone accelerates leaf and fruit drop in plants?
- A Ethylene
- B Cytokinin
- C Auxin
- D Gibberellin
Correct answer: Ethylene
Ethylene promotes abscission, which is the shedding of leaves, flowers, or fruits. This process occurs naturally during plant development.
Which plant hormone acts with auxin, their ratio deciding whether a tissue culture develops roots or shoots?
- A Ethylene
- B Abscisic acid
- C Gibberellin
- D Cytokinin
Correct answer: Cytokinin
The auxin to cytokinin ratio determines organ formation in culture: a higher share of auxin favours root development, while a higher share of cytokinin favours shoot development. The two hormones also jointly regulate cell division and differentiation.
Which hormone is commonly used in agriculture to stimulate seed germination?
- A Ethylene
- B Cytokinin
- C Abscisic acid
- D Gibberellin
Correct answer: Gibberellin
Gibberellins are used in agriculture to stimulate seed germination and increase crop growth. They help break seed dormancy.