TRB BT Assistant - Plant Growth Regulators and Development Online Test (MCQ Quiz)

1. Which class of plant hormones is primarily responsible for promoting cell division and expansion?

A) Auxins B) Gibberellins C) Cytokinins D) Abscisic Acid

2. What is the main function of auxins in plant growth?

A) Promoting root formation and apical dominance B) Stimulating flowering and fruit development C) Delaying senescence and promoting seed germination D) Inducing stomatal closure and dormancy

3. Gibberellins are known for their role in:

A) Fruit ripening B) Stem elongation and breaking seed dormancy C) Leaf abscission D) Stress response

4. Which plant hormone acts as an antagonist to auxins and gibberellins, often inhibiting growth?

A) Ethylene B) Cytokinin C) Abscisic Acid (ABA) D) Brassinosteroids

5. Ethylene is a gaseous plant hormone primarily associated with:

A) Cell division in meristems B) Phototropism C) Fruit ripening and senescence D) Root elongation

6. The phenomenon of apical dominance, where the terminal bud inhibits the growth of lateral buds, is mainly controlled by which plant hormone?

A) Cytokinin B) Gibberellin C) Auxin D) Abscisic Acid

7. Which plant growth regulator is widely used commercially to promote flowering in pineapple?

A) Gibberellic acid B) Ethephon C) Cytokinin D) Indole-3-acetic acid (IAA)

8. What is the primary role of abscisic acid (ABA) during drought stress?

A) Promoting root growth B) Inducing stomatal closure to conserve water C) Stimulating photosynthesis D) Enhancing nutrient uptake

9. The process of seed germination is often promoted by which class of plant hormones?

A) Auxins B) Abscisic Acid C) Gibberellins D) Ethylene

10. Which hormone is synthesized in the root tips and transported upwards to influence shoot growth?

A) Cytokinin B) Ethylene C) Gibberellin D) Auxin

11. Vernalization is a process that requires a period of cold treatment to induce flowering. Which plant hormone is thought to be involved in mediating this response?

A) Auxin B) Gibberellin C) Abscisic Acid D) Cytokinin

12. The 'triple response' in etiolated seedlings, characterized by inhibition of stem elongation, swelling of the hypocotyl, and horizontal root growth, is induced by:

A) High levels of auxin B) High levels of gibberellin C) High levels of ethylene D) Low levels of abscisic acid

13. Which plant hormone is most effective in delaying leaf senescence?

A) Abscisic Acid B) Ethylene C) Cytokinin D) Gibberellin

14. Plant tropisms, such as phototropism and gravitropism, are primarily mediated by:

A) Cytokinins B) Gibberellins C) Auxins D) Ethylene

15. Which of the following is a naturally occurring auxin in plants?

A) Indole-3-butyric acid (IBA) B) Kinetin C) Abscisic acid (ABA) D) Ethylene

16. The process by which plants respond to gravity is called gravitropism. The hormone primarily responsible for sensing gravity and mediating the response in shoots and roots is:

A) Cytokinin B) Ethylene C) Gibberellin D) Auxin

17. Which plant hormone is synthesized in response to environmental stresses like water deficit, salinity, and cold?

A) Gibberellin B) Ethylene C) Abscisic Acid D) Cytokinin

18. The phenomenon of short-day plants flowering only when the nights are longer than a critical period is related to the perception of:

A) Gibberellin levels B) Auxin concentration C) Phytochrome and light duration D) Ethylene production

19. Which plant growth regulator is used to promote fruit thinning in apples and pears?

A) Gibberellin B) Cytokinin C) Auxin (e.g., NAA) D) Abscisic Acid

20. The development of adventitious roots from stem cuttings is often enhanced by the application of synthetic auxins like:

A) Indole-3-acetic acid (IAA) B) Indole-3-butyric acid (IBA) C) Kinetin D) Gibberellic acid (GA3)

21. Which hormone is involved in the formation of vascular tissues (xylem and phloem)?

A) Ethylene B) Abscisic Acid C) Auxin and Cytokinin D) Gibberellin

22. The ability of plant cells to divide and differentiate is significantly influenced by the ratio of:

A) Auxin to Gibberellin B) Cytokinin to Auxin C) Abscisic Acid to Ethylene D) Gibberellin to Ethylene

23. Which plant hormone is synthesized in the leaves and transported to other parts of the plant, often promoting dormancy?

A) Ethylene B) Cytokinin C) Abscisic Acid D) Auxin

24. The growth of plant organs in response to touch or mechanical stimulation is called:

A) Phototropism B) Thigmotropism C) Gravitropism D) Nastic movements

25. Which of the following is a brassinosteroid, a class of plant hormones known to promote growth and development?

A) Jasmonic acid B) Salicylic acid C) Brassinolic acid D) Abscisic acid

26. The process of flowering in many plants is regulated by photoreceptors like phytochrome and the hormone:

A) Auxin B) Gibberellin C) Florigen (hypothetical hormone) D) Ethylene

27. What is the role of jasmonates in plant development?

A) Promoting cell division B) Mediating defense responses against herbivores and pathogens C) Stimulating root growth D) Inducing flowering

28. The phenomenon where a plant bends towards a light source is known as:

A) Gravitropism B) Thigmotropism C) Phototropism D) Nyctinasty

29. Which plant hormone is essential for the development of fruit set and preventing premature fruit drop?

A) Cytokinin B) Abscisic Acid C) Gibberellin D) Ethylene

30. The formation of secondary growth (e.g., increase in stem diameter) in woody plants is influenced by:

A) Cytokinins and auxins B) Gibberellins and ABA C) Ethylene and brassinosteroids D) ABA and cytokinins

31. Which plant hormone is involved in the abscission (shedding) of leaves, fruits, and flowers?

A) Auxin B) Gibberellin C) Ethylene and Abscisic Acid D) Cytokinin

32. The plant hormone indole-3-acetic acid (IAA) is synthesized primarily in:

A) Mature leaves B) Root tips and young leaves C) Mature stems D) Flower petals

33. Which plant hormone is critical for maintaining the totipotency of plant cells and is used in tissue culture to induce cell division and shoot formation?

A) Auxin B) Gibberellin C) Cytokinin D) Abscisic Acid

34. The process by which plants respond to touch, leading to twining or coiling, is called:

A) Phototropism B) Gravitropism C) Chemotropism D) Thigmotropism

35. Which hormone is often referred to as the 'stress hormone' of plants due to its role in mediating responses to adverse conditions?

A) Gibberellin B) Ethylene C) Cytokinin D) Abscisic Acid

36. The phenomenon of delayed flowering in response to photoperiod is regulated by the pigment:

A) Carotenoid B) Phytochrome C) Chlorophyll D) Anthocyanin

37. Which plant hormone is a key regulator of seed dormancy?

A) Auxin B) Gibberellin C) Abscisic Acid D) Ethylene

38. The growth of roots in response to gravity is known as:

A) Positive gravitropism B) Negative gravitropism C) Positive phototropism D) Negative phototropism

39. Which plant hormone promotes the formation of adventitious roots and is used in rooting powders?

A) Cytokinin B) Gibberellin C) Indole-3-butyric acid (IBA) D) Abscisic Acid

40. The opening and closing of stomata are influenced by which plant hormone?

A) Auxin B) Gibberellin C) Abscisic Acid D) Cytokinin

41. Which plant hormone is involved in the ripening of climacteric fruits like bananas and tomatoes?

A) Auxin B) Gibberellin C) Ethylene D) Cytokinin

42. The production of ethylene is often increased in response to:

A) Low temperature B) Mechanical stress and wounding C) High light intensity D) Abundant water

43. Which plant hormone is synthesized in the developing seeds and is involved in maintaining seed dormancy and preventing vivipary?

A) Gibberellin B) Ethylene C) Cytokinin D) Abscisic Acid

44. The elongation of internodes in grasses is a well-known effect of:

A) Auxins B) Cytokinins C) Gibberellins D) Abscisic Acid

45. Which hormone promotes lateral bud growth and is often applied along with auxin to induce callus formation in tissue culture?

A) Gibberellin B) Abscisic Acid C) Ethylene D) Cytokinin

46. The phenomenon of delayed senescence and enhanced nutrient mobilization in aging leaves is attributed to:

A) Abscisic Acid B) Ethylene C) Cytokinin D) Gibberellin

47. Plant growth regulators are often classified into two main groups: growth promoters and growth inhibitors. Which of the following is primarily a growth inhibitor?

A) Auxin B) Gibberellin C) Cytokinin D) Abscisic Acid

48. Which plant hormone is synthesized in the shoot apical meristem and transported basipetally to control apical dominance?

A) Cytokinin B) Gibberellin C) Auxin D) Ethylene

49. The development of female flowers in cucurbits can be induced by applying:

A) Gibberellins B) Auxins C) Ethylene D) Abscisic Acid

50. Which of the following is an important role of salicylic acid in plants?

A) Promoting seed germination B) Mediating defense responses against pathogens C) Stimulating fruit ripening D) Inducing flowering

Plant Growth Regulators and Development - Online Test

Test Results