50 Most Important NEET PYQs of Chapter 15: Plant Growth and Development – Part 1 (Q1–25)

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 ðŸŠī 50 Most Important NEET PYQs of Chapter 15: Plant Growth and Development – Part 1 (Q1–25)

📘 By neetpyqall | biologyatease1.blogspot.com


1. Which one is a growth inhibitor?

A) IAA
B) GA
C) ABA
D) Kinetin
✅ Answer: C) ABA
🧠 Explanation: Abscisic acid (ABA) is known as a growth inhibitor because it promotes dormancy and abscission, and inhibits seed germination.

2. Gibberellins cause:

A) Inhibition of cell division
B) Cell elongation
C) Stomatal closure
D) Leaf fall
✅ Answer: B) Cell elongation
🧠 Explanation: Gibberellins promote stem elongation and leaf expansion by stimulating cell elongation and breaking seed dormancy.

3. The function of cytokinins is:

A) Inhibiting cell division
B) Promoting root growth
C) Promoting cell division
D) Promoting abscission
✅ Answer: C) Promoting cell division
🧠 Explanation: Cytokinins promote cytokinesis (cell division), especially in actively growing tissues.

4. Which hormone delays leaf senescence?

A) ABA
B) Cytokinin
C) Ethylene
D) Auxin
✅ Answer: B) Cytokinin
🧠 Explanation: Cytokinins delay leaf senescence by promoting nutrient mobilization.

5. Bolting in plants is promoted by:

A) Auxin
B) ABA
C) Ethylene
D) Gibberellins
✅ Answer: D) Gibberellins
🧠 Explanation: Gibberellins promote bolting (elongation of internodes) in rosette plants before flowering.

6. Avena curvature test is used to study:

A) Gibberellins
B) Cytokinins
C) Ethylene
D) Auxin
✅ Answer: D) Auxin
🧠 Explanation: The Avena curvature test measures the effect of auxin on coleoptile curvature and growth.

7. Vernalization stimulates:

A) Seed dormancy
B) Leaf fall
C) Flowering
D) Germination
✅ Answer: C) Flowering
🧠 Explanation: Vernalization is the induction of flowering by exposure to low temperatures.

8. Photoperiodism affects:

A) Transpiration
B) Photosynthesis
C) Stomatal movement
D) Flowering
✅ Answer: D) Flowering
🧠 Explanation: Photoperiodism is the physiological reaction of organisms to the length of day or night, particularly affecting flowering in plants.

9. Hormone responsible for fruit ripening is:

A) Auxin
B) Cytokinin
C) Ethylene
D) ABA
✅ Answer: C) Ethylene
🧠 Explanation: Ethylene regulates fruit ripening and is often called the ripening hormone.

10. Which hormone is called ‘stress hormone’?

A) Auxin
B) Gibberellin
C) Cytokinin
D) Abscisic Acid
✅ Answer: D) Abscisic Acid
🧠 Explanation: ABA helps plants cope with environmental stress like drought by inducing stomatal closure.

11. Which hormone promotes parthenocarpy?

A) Gibberellin
B) ABA
C) Cytokinin
D) Ethylene
✅ Answer: A) Gibberellin
🧠 Explanation: Gibberellins promote fruit development without fertilization (parthenocarpy), especially in tomatoes.

12. Apical dominance is mainly controlled by:

A) Cytokinin
B) Auxin
C) Gibberellin
D) Ethylene
✅ Answer: B) Auxin
🧠 Explanation: Auxin produced at the shoot tip inhibits the growth of lateral buds, a phenomenon known as apical dominance.

13. Plant hormone responsible for epinasty:

A) ABA
B) Ethylene
C) Cytokinin
D) Auxin
✅ Answer: B) Ethylene
🧠 Explanation: Epinasty is the downward bending of leaves due to more growth on the upper side, caused by ethylene.

14. Which plant hormone is gaseous?

A) ABA
B) Ethylene
C) Cytokinin
D) Auxin
✅ Answer: B) Ethylene
🧠 Explanation: Ethylene is the only gaseous plant hormone involved in ripening, abscission, and senescence.

15. The process of seed germination involves:

A) Mitosis only
B) Only imbibition
C) Mobilization of stored food
D) Photosynthesis
✅ Answer: C) Mobilization of stored food
🧠 Explanation: During germination, stored food is broken down to provide energy for the growing embryo.

16. Dormancy of seeds can be broken by:

A) Gibberellin
B) ABA
C) Ethylene
D) Cytokinin
✅ Answer: A) Gibberellin
🧠 Explanation: Gibberellins break seed dormancy and promote germination by activating enzymes like amylase.

17. The growth of plants is:

A) Limited
B) Determinate
C) Indeterminate
D) None
✅ Answer: C) Indeterminate
🧠 Explanation: Most plant tissues can divide and grow throughout life, hence growth is often indeterminate.

18. Which plant hormone is involved in phototropism?

A) Gibberellin
B) Cytokinin
C) Auxin
D) ABA
✅ Answer: C) Auxin
🧠 Explanation: Auxin redistributes to the shaded side of the stem and promotes elongation, causing the stem to bend toward light.

19. Which of the following is not a natural plant hormone?

A) IAA
B) NAA
C) Ethylene
D) ABA
✅ Answer: B) NAA
🧠 Explanation: NAA (Naphthalene Acetic Acid) is a synthetic auxin, not naturally produced by plants.

20. Which one is incorrectly paired?

A) ABA – Dormancy
B) Ethylene – Fruit ripening
C) Cytokinin – Cell division
D) Gibberellin – Inhibits seed germination
✅ Answer: D) Gibberellin – Inhibits seed germination
🧠 Explanation: Gibberellins promote, not inhibit, seed germination.

21. Which hormone induces senescence?

A) Auxin
B) Cytokinin
C) Gibberellin
D) Ethylene
✅ Answer: D) Ethylene
🧠 Explanation: Ethylene promotes leaf and flower senescence and abscission.

22. Which of the following is used to increase sugar content in sugarcane?

A) Cytokinin
B) ABA
C) Gibberellin
D) Auxin
✅ Answer: C) Gibberellin
🧠 Explanation: Gibberellins enhance internode elongation and sugar accumulation in sugarcane.

23. Which plant hormone was first discovered?

A) Ethylene
B) Cytokinin
C) Auxin
D) Gibberellin
✅ Answer: C) Auxin
🧠 Explanation: Auxin (specifically IAA) was the first plant hormone to be discovered by Charles Darwin.

24. Which hormone causes abscission?

A) Cytokinin
B) Gibberellin
C) Ethylene
D) IAA
✅ Answer: C) Ethylene
🧠 Explanation: Ethylene accelerates abscission of leaves and fruits.

25. Which process involves irreversible increase in size?

A) Growth
B) Movement
C) Turgidity
D) Translocation
✅ Answer: A) Growth
🧠 Explanation: Growth is defined as a permanent and irreversible increase in size or mass.

ðŸŒą That’s the end of Part 1 (Q1–25) of NEET PYQs from Chapter 15: Plant Growth and Development!

👉 Ready for Part 2 (Q26–50)? Just say “next” and we’ll continue!
📍 Follow for daily NEET PYQs and explanations:
🔗 neetpyqall.blogspot.com
🔗 biologyatease1.blogspot.com

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