Prepare for NEET Biology Plant Growth and Development with MCQs & PYQs on NEET.GUIDE. Get free practice, previous year questions, and expert insights on plant hormones and growth regulators.
A mutation affects the function of the Hox genes in a developing Drosophila embryo. Which of the following is the MOST likely consequence?
Premature termination of embryonic development.
Failure of gastrulation.
Homeotic transformations, leading to segments developing with characteristics of other segments.
Lack of differentiation of germ layers.
A plant hormone promotes bolting in rosette plants and is also antagonistic to the effects of abscisic acid on alpha-amylase activity. This hormone also plays a key role in apical dominance. Which of the following hormones fits this description?
Gibberellin
Auxin
Cytokinin
Ethylene
The 'Richmond-Lang effect', which refers to the delay of senescence in leaves by cytokinins, is primarily attributed to their influence on:
Ethylene production
Cell wall synthesis
Nutrient mobilization
Stomatal closure
A short-day plant is exposed to a flash of red light during the critical dark period. This is immediately followed by a flash of far-red light. What is the most likely outcome?
Flowering will be inhibited.
Flowering will be promoted.
The plant will become a long-day plant.
The far-red light will have no effect.
A plant species exhibits a critical dark period of 14 hours. Which of the following light/dark regimes would MOST LIKELY prevent flowering?
10 hours light / 10 hours dark
14 hours light / 10 hours dark
10 hours light / 14 hours dark
15 hours light / 9 hours dark
A long-day plant with a critical dark period of 9 hours is grown under short-day conditions. Which treatment is MOST LIKELY to induce flowering?
Increasing the ambient temperature during the dark period.
Spraying the plant with gibberellins during the light period.
Interrupting the dark period with a brief exposure to red light.
Exposing the plant to far-red light at the end of the dark period.
A dormant seed of a desert plant imbibes water but fails to germinate even under optimal temperature and oxygen availability. Which of the following is the MOST LIKELY explanation for this continued dormancy?
Insufficient light exposure to trigger phytochrome conversion.
Presence of inhibitors like abscisic acid in the seed coat.
Immature embryo requiring a period of after-ripening.
Hard seed coat impermeable to oxygen, preventing respiration.
Which of the following combinations of factors is MOST LIKELY to break seed dormancy in a species exhibiting combinational dormancy?
Exposure to high temperatures followed by gibberellic acid application.
Scarification followed by exposure to high oxygen levels.
Cold stratification followed by exposure to light.
Soaking in water followed by exposure to ethylene.
Some seeds require a specific duration of light exposure to germinate. If a flash of red light (R) is given, followed immediately by a flash of far-red light (FR), what is the MOST LIKELY effect on germination?
Germination will be stimulated.
Germination will be inhibited.
Germination will be unaffected.
The effect will depend on the seed species.
In some plant species, seed dormancy is broken by the action of microorganisms in the soil. Which mechanism is MOST LIKELY involved in this process?
Microbial production of gibberellins that stimulate germination.
Microbial degradation of germination inhibitors in the seed coat.
Microbial enhancement of oxygen availability to the embryo.
Microbial scarification of the seed coat, allowing water imbibition.
