50 Most Important NEET PYQs of Chapter 15: Plant Growth and Development – Part 2 (Q26–50)

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 ðŸŠī 50 Most Important NEET PYQs of Chapter 15: Plant Growth and Development – Part 2 (Q26–50)

📘 By neetpyqall | biologyatease1.blogspot.com

Continuing with Part 2! Let’s crack the next set of most important NEET previous year questions for Chapter 15, Plant Growth and Development.

26. Which plant hormone can replace cold treatment for flowering?

A) Auxin
B) Cytokinin
C) Gibberellin
D) ABA
✅ Answer: C) Gibberellin
🧠 Explanation: Gibberellins can substitute for cold treatment (vernalization) to induce flowering in some plants.

27. Dedifferentiation means:

A) Differentiation of meristematic cells
B) Conversion of mature cells into meristematic cells
C) Loss of ability to divide
D) All of the above
✅ Answer: B) Conversion of mature cells into meristematic cells
🧠 Explanation: Dedifferentiation is when mature cells regain the ability to divide and form meristems like interfascicular cambium.

28. Which process does red light regulate?

A) Phototropism
B) Germination
C) Photosynthesis
D) Growth inhibition
✅ Answer: B) Germination
🧠 Explanation: Red light promotes seed germination through phytochrome activation.

29. During apical dominance, lateral buds:

A) Grow rapidly
B) Are promoted
C) Are suppressed
D) Differentiate into flowers
✅ Answer: C) Are suppressed
🧠 Explanation: Due to auxin produced by apical buds, the growth of lateral buds is suppressed.

30. Which plant hormone induces flowering in long-day plants?

A) Cytokinin
B) Gibberellin
C) Ethylene
D) Auxin
✅ Answer: B) Gibberellin
🧠 Explanation: Gibberellins promote flowering in long-day plants even without appropriate photoperiods.

31. Differentiation is:

A) Loss of division ability
B) Acquisition of a specific function
C) Regaining ability to divide
D) Increase in size only
✅ Answer: B) Acquisition of a specific function
🧠 Explanation: Differentiation leads to development of specific structures or functions in cells.

32. Which of the following is not a feature of growth?

A) Irreversible
B) Measurable
C) Energy consuming
D) Temporary
✅ Answer: D) Temporary
🧠 Explanation: Growth is a permanent and irreversible increase in size.

33. Scarification is:

A) Removal of seed coat
B) Cooling treatment
C) Exposure to light
D) Exposure to hormones
✅ Answer: A) Removal of seed coat
🧠 Explanation: Scarification breaks seed dormancy by weakening or removing the hard seed coat.

34. The hormone which promotes leaf fall (abscission) is:

A) Auxin
B) Cytokinin
C) ABA
D) Gibberellin
✅ Answer: C) ABA
🧠 Explanation: Abscisic acid (ABA) promotes abscission along with ethylene.

35. A plant showing short day requirement for flowering will not flower if:

A) Days are shorter than critical period
B) Days are longer than critical period
C) Days and nights are equal
D) Night is longer than critical period
✅ Answer: B) Days are longer than critical period
🧠 Explanation: Short-day plants require nights longer than a critical duration for flowering.

36. Which of the following is a synthetic auxin?

A) IAA
B) GA
C) NAA
D) ABA
✅ Answer: C) NAA
🧠 Explanation: Naphthalene acetic acid (NAA) is a synthetic form of auxin used in agriculture.

37. Ethylene is synthesized from:

A) Tryptophan
B) Methionine
C) Cytokinin
D) Acetyl CoA
✅ Answer: B) Methionine
🧠 Explanation: Methionine serves as the precursor for ethylene biosynthesis.

38. ABA promotes:

A) Seed germination
B) Cell division
C) Seed dormancy
D) Cell elongation
✅ Answer: C) Seed dormancy
🧠 Explanation: ABA helps maintain seed dormancy under unfavorable conditions.

39. The phenomenon of movement of seedling toward light is:

A) Phototropism
B) Photoperiodism
C) Vernalization
D) Chemotropism
✅ Answer: A) Phototropism
🧠 Explanation: Movement of a plant organ towards light is called phototropism, primarily regulated by auxin.

40. Which statement is true about secondary growth?

A) It occurs by primary meristem
B) It increases length
C) It occurs only in roots
D) It increases girth
✅ Answer: D) It increases girth
🧠 Explanation: Secondary growth (by vascular cambium and cork cambium) increases the thickness (girth) of stems and roots.

41. Which enzyme breaks starch during seed germination?

A) Protease
B) Amylase
C) Lipase
D) Invertase
✅ Answer: B) Amylase
🧠 Explanation: Amylase breaks down starch into sugars during germination to provide energy.

42. Maximum plant growth is observed during:

A) Senescence phase
B) Lag phase
C) Log phase
D) Maturity phase
✅ Answer: C) Log phase
🧠 Explanation: In the log phase, growth is at its peak due to high metabolic activity.

43. Fruit ripening is an example of:

A) Positive feedback
B) Negative feedback
C) Feedforward mechanism
D) None of these
✅ Answer: A) Positive feedback
🧠 Explanation: Ethylene production increases further ethylene production, an example of positive feedback.

44. Growth curve is:

A) Linear
B) Zigzag
C) Sigmoid
D) Exponential only
✅ Answer: C) Sigmoid
🧠 Explanation: The typical plant growth curve is sigmoid (S-shaped) showing lag, log, and stationary phases.

45. Natural auxin is:

A) NAA
B) IBA
C) 2,4-D
D) IAA
✅ Answer: D) IAA
🧠 Explanation: Indole-3-acetic acid (IAA) is a natural auxin synthesized by plants.

46. Which hormone induces flowering in pineapple?

A) Cytokinin
B) Ethylene
C) Auxin
D) Gibberellin
✅ Answer: B) Ethylene
🧠 Explanation: Ethylene is used commercially to induce flowering in pineapple plants.

47. Growth rate of plants can be measured by:

A) Increase in size
B) Increase in number of cells
C) Increase in fresh/dry weight
D) All of the above
✅ Answer: D) All of the above
🧠 Explanation: Growth can be measured by changes in length, volume, fresh weight, or dry weight.

48. Sprouting of potato tuber is an example of:

A) Germination
B) Vegetative growth
C) Dormancy
D) Reproduction
✅ Answer: B) Vegetative growth
🧠 Explanation: Sprouting is vegetative growth, where buds on tubers develop into new shoots.

49. Which hormone promotes the synthesis of hydrolytic enzymes during germination?

A) Ethylene
B) ABA
C) Gibberellin
D) Cytokinin
✅ Answer: C) Gibberellin
🧠 Explanation: Gibberellins promote the synthesis of hydrolytic enzymes like amylase during seed germination.

50. In plants, senescence starts from:

A) Apex
B) Base
C) Middle
D) Uniformly
✅ Answer: A) Apex
🧠 Explanation: Senescence often begins from the apical parts and progresses downward.

ðŸŒą That’s it! You’ve now completed all 50 NEET PYQs from Chapter 15: Plant Growth and Development!
📍 Stay consistent with your practice and revise these questions frequently.

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