Part 8 – More Complex & Conceptual Case-based NEET Questions
Part 8 – More Complex & Conceptual Case-based NEET Questions
Q176. A farmer wants to produce uniform ripening of bananas before sending them to the market. Which treatment is best?
a) Gibberellin spray
b) Auxin application
c) Cytokinin treatment
d) Ethylene exposure
Answer: d) Ethylene exposure
- a) Gibberellin – Incorrect. Promotes elongation, not ripening.
- b) Auxin – Incorrect. Can induce parthenocarpy but not ripening.
- c) Cytokinin – Incorrect. Delays senescence, not ripening.
- d) Ethylene – Correct. Used commercially for uniform fruit ripening.
Q177. If the apical bud of a plant is removed, lateral buds start growing. Which hormone mainly caused suppression earlier?
a) Cytokinin
b) Auxin
c) Gibberellin
d) ABA
Answer: b) Auxin
- a) Cytokinin – Incorrect. Promotes lateral bud growth.
- b) Auxin – Correct. Apical dominance is due to auxin.
- c) Gibberellin – Incorrect. Promotes elongation, not suppression.
- d) ABA – Incorrect. Causes dormancy, not bud suppression.
Q178. A plant is exposed to water stress. Which hormone concentration is expected to rise?
a) Auxin
b) Gibberellin
c) ABA
d) Cytokinin
Answer: c) ABA
- a) Auxin – Incorrect. Not related to stress.
- b) Gibberellin – Incorrect. Promotes growth, not stress response.
- c) ABA – Correct. Stress hormone → closes stomata during drought.
- d) Cytokinin – Incorrect. Promotes growth, not stress response.
Q179. During malting of barley seeds for beer production, which hormone is crucial for hydrolytic enzyme secretion?
a) Auxin
b) ABA
c) Gibberellin
d) Cytokinin
Answer: c) Gibberellin
- a) Auxin – Incorrect. Not enzyme inducer.
- b) ABA – Incorrect. Inhibits germination.
- c) Gibberellin – Correct. Induces α-amylase in aleurone layer.
- d) Cytokinin – Incorrect. No role in malting.
Q180. Which plant growth regulator is commonly used in tissue culture to induce shoot formation?
a) High auxin : Low cytokinin
b) High cytokinin : Low auxin
c) High gibberellin : Low cytokinin
d) Only ABA
Answer: b) High cytokinin : Low auxin
- a) High auxin : Low cytokinin – Incorrect. Induces roots.
- b) High cytokinin : Low auxin – Correct. Promotes shoot organogenesis.
- c) High GA : Low cytokinin – Incorrect. Not used in tissue culture.
- d) ABA – Incorrect. Inhibits organogenesis.
Q181. In rosette plants (cabbage, beet), bolting before flowering can be artificially induced by:
a) Cytokinin
b) ABA
c) Gibberellin
d) Ethylene
Answer: c) Gibberellin
- a) Cytokinin – Incorrect. No role in bolting.
- b) ABA – Incorrect. Growth inhibitor.
- c) Gibberellin – Correct. Induces stem elongation (bolting).
- d) Ethylene – Incorrect. Involved in senescence, not bolting.
Q182. A seedless tomato was developed in a lab by applying hormones. Which hormones are likely used?
a) Cytokinin & ABA
b) Gibberellin & Auxin
c) ABA & Ethylene
d) Only Gibberellin
Answer: b) Gibberellin & Auxin
- a) Cytokinin + ABA – Incorrect. Not linked to parthenocarpy.
- b) Gibberellin & Auxin – Correct. Both can induce parthenocarpy.
- c) ABA + Ethylene – Incorrect. Promote dormancy/senescence.
- d) Only GA – Incorrect. Auxin is also effective.
Q183. In cucumber, which hormones regulate sex expression?
a) Auxin (male) & Ethylene (female)
b) Ethylene (female) & Gibberellin (male)
c) Cytokinin (female) & ABA (male)
d) Auxin (female) & Gibberellin (female)
Answer: b) Ethylene (female) & Gibberellin (male)
- a) Auxin (male) – Incorrect. No role in sex expression.
- b) Ethylene (female) & Gibberellin (male) – Correct. Known in cucurbits.
- c) Cytokinin & ABA – Incorrect. Not related.
- d) Auxin & GA – Incorrect. Auxin is not sex-related.
Q184. Which hormone is responsible for vivipary (precocious germination in seeds)?
a) Decrease in ABA
b) Increase in auxin
c) Decrease in GA
d) Increase in cytokinin
Answer: a) Decrease in ABA
- a) Decrease in ABA – Correct. ABA maintains dormancy; low ABA → vivipary.
- b) Increase in auxin – Incorrect. Not linked.
- c) Decrease in GA – Incorrect. Opposite, GA promotes germination.
- d) Increase in cytokinin – Incorrect. Not related.
Q185. A plant with mutation in auxin transport shows reduced apical dominance. Which reason is correct?
a) Auxin fails to accumulate in root tips
b) Auxin fails to move basipetally from shoot apex
c) Cytokinin concentration increases in leaves
d) ABA concentration decreases in buds
Answer: b) Auxin fails to move basipetally from shoot apex
- a) Root tips – Incorrect. Apical dominance is a shoot phenomenon.
- b) Basipetal transport – Correct. Auxin must move downward to suppress buds.
- c) Cytokinin increase – Incorrect. Indirect effect, not main reason.
- d) ABA decrease – Incorrect. Not involved in dominance.
Q186. The “foolish seedling” disease of rice is due to:
a) Excess auxin
b) Excess gibberellin
c) Deficiency of cytokinin
d) ABA accumulation
Answer: b) Excess gibberellin
- a) Auxin – Incorrect. Not disease-linked.
- b) Gibberellin – Correct. Gibberella fujikuroi produces GA → abnormal elongation.
- c) Cytokinin deficiency – Incorrect. Would cause reduced division.
- d) ABA – Incorrect. Causes dormancy, not elongation.
Q187. Which hormone induces stomatal closure under drought conditions?
a) Auxin
b) ABA
c) Cytokinin
d) Ethylene
Answer: b) ABA
- a) Auxin – Incorrect. No role in stomatal closure.
- b) ABA – Correct. Stress hormone closes stomata to prevent water loss.
- c) Cytokinin – Incorrect. Not stress-related.
- d) Ethylene – Incorrect. Affects ripening, not stomata.
Q188. A scientist applied auxin paste near the tip of a decapitated plant shoot. The lateral buds again got suppressed. This experiment proves:
a) Apical dominance is due to auxin
b) Gibberellins are essential for bud suppression
c) Cytokinin is responsible for dominance
d) ABA controls apical dominance
Answer: a) Apical dominance is due to auxin
- a) Auxin – Correct. Classic experiment by Thimann & Skoog.
- b) Gibberellin – Incorrect. Elongation hormone.
- c) Cytokinin – Incorrect. Opposite effect.
- d) ABA – Incorrect. Not related.
Q189. Which hormone pair works synergistically in cell elongation?
a) Auxin + Gibberellin
b) Auxin + ABA
c) Cytokinin + ABA
d) Gibberellin + ABA
Answer: a) Auxin + Gibberellin
- a) Auxin + Gibberellin – Correct. Work together for elongation.
- b) Auxin + ABA – Incorrect. ABA is inhibitory.
- c) Cytokinin + ABA – Incorrect. Not synergistic.
- d) GA + ABA – Incorrect. Antagonistic.
Q190. If a plant is sprayed with cytokinin, what will likely happen?
a) Leaves senesce faster
b) Nutrient mobilization increases
c) Apical dominance increases
d) Flowering is inhibited
Answer: b) Nutrient mobilization increases
- a) Senesce faster – Incorrect. Cytokinin delays senescence.
- b) Nutrient mobilization – Correct. Cytokinin keeps leaves green.
- c) Apical dominance – Incorrect. Reduced by cytokinin.
- d) Flowering inhibition – Incorrect. No direct effect.
Q191. Which plant hormone is used to increase fruit size in grapes?
a) Auxin
b) Gibberellin
c) Cytokinin
d) ABA
Answer: b) Gibberellin
- a) Auxin – Incorrect. Tomato parthenocarpy, not grapes.
- b) Gibberellin – Correct. Increases grape cluster size.
- c) Cytokinin – Incorrect. Cell division, not elongation.
- d) ABA – Incorrect. Stress hormone.
Q192. Which hormone maintains seed dormancy?
a) Gibberellin
b) Cytokinin
c) ABA
d) Auxin
Answer: c) ABA
- a) Gibberellin – Incorrect. Breaks dormancy.
- b) Cytokinin – Incorrect. Division, not dormancy.
- c) ABA – Correct. Inhibits germination.
- d) Auxin – Incorrect. No role in dormancy.
Q193. Which hormone combination induces callus formation in tissue culture?
a) Low auxin : High cytokinin
b) Equal auxin : Equal cytokinin
c) High auxin : Low cytokinin
d) Only gibberellin
Answer: b) Equal auxin : Equal cytokinin
- a) Low auxin : High cytokinin – Incorrect. Shoots.
- b) Equal auxin : Equal cytokinin – Correct. Callus formation.
- c) High auxin : Low cytokinin – Incorrect. Roots.
- d) GA – Incorrect. Not used in callus induction.
Q194. Which hormone helps in breaking potato tuber dormancy?
a) ABA
b) Ethylene
c) Cytokinin
d) Gibberellin
Answer: d) Gibberellin
- a) ABA – Incorrect. Maintains dormancy.
- b) Ethylene – Incorrect. Used in fruit ripening.
- c) Cytokinin – Incorrect. Not directly dormancy breaking.
- d) Gibberellin – Correct. Sprouting in potatoes.
Q195. In rice plants infected with Gibberella fujikuroi, abnormal elongation occurs due to:
a) Excess auxin
b) Gibberellin secretion
c) ABA accumulation
d) Cytokinin deficiency
Answer: b) Gibberellin secretion
- a) Auxin – Incorrect. Not disease-related.
- b) Gibberellin – Correct. Fungus produces gibberellins → bakanae disease.
- c) ABA – Incorrect. Not linked.
- d) Cytokinin – Incorrect. Not cause.
Q196. Which hormone promotes differentiation of chloroplasts in leaves?
a) Auxin
b) Gibberellin
c) Cytokinin
d) ABA
Answer: c) Cytokinin
- a) Auxin – Incorrect. Elongation, not plastid differentiation.
- b) GA – Incorrect. Not related to chloroplasts.
- c) Cytokinin – Correct. Promotes chloroplast maturation.
- d) ABA – Incorrect. Opposite effect.
Q197. A gardener applies IBA on stem cuttings of rose. Expected result is:
a) Inhibition of root initiation
b) Promotion of root initiation
c) Abnormal flowering
d) Delay in senescence
Answer: b) Promotion of root initiation
- a) Inhibition – Incorrect. IBA induces roots.
- b) Promotion – Correct. IBA is rooting hormone.
- c) Flowering – Incorrect. Not linked.
- d) Senescence – Incorrect. Cytokinin controls that.
Q198. In lettuce seeds, germination requires red light exposure and gibberellins. Which statement is correct?
a) Red light converts Pfr to Pr, promoting germination
b) Pfr induces GA synthesis, promoting germination
c) Pr is the active form of phytochrome
d) ABA increases under red light
Answer: b) Pfr induces GA synthesis, promoting germination
- a) Red light → Pfr to Pr – Incorrect. Red light converts Pr → Pfr.
- b) Pfr induces GA synthesis – Correct. Pfr + GA promote germination.
- c) Pr – Incorrect. Pfr is active form.
- d) ABA – Incorrect. Red light reduces ABA.
Q199. A scientist treated a plant with high cytokinin but low auxin. What is most likely to occur?
a) Only root formation
b) Only shoot formation
c) Callus remains undifferentiated
d) Seeds enter dormancy
Answer: b) Only shoot formation
- a) Root – Incorrect. Needs high auxin.
- b) Shoot – Correct. High cytokinin → shoot organogenesis.
- c) Callus – Incorrect. Equal ratio required.
- d) Dormancy – Incorrect. ABA controls dormancy.
Q200. A farmer applies gibberellin to sugarcane crop. What is the expected benefit?
a) Delay in senescence
b) Increase in internode length → higher yield
c) Faster ripening of canes
d) Induction of seed dormancy
Answer: b) Increase in internode length → higher yield
- a) Delay in senescence – Incorrect. Cytokinin does this.
- b) Increase in internode length – Correct. GA increases cane yield.
- c) Faster ripening – Incorrect. Ethylene is ripening hormone.
- d) Dormancy – Incorrect. ABA induces dormancy.
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