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Free Forms and Functions of Plants MCQs with Answers

272 Forms and Functions of Plants MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.

Plant nutrition and transport cover mineral uptake, photosynthesis, xylem movement of water and minerals, and phloem translocation of sugars. Plant growth regulators include auxins, gibberellins, cytokinins, abscisic acid and ethene, whose effects on cell division, elongation, dormancy, fruit ripening and tropic responses should not be confused with mineral nutrition.

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Plant Nutrition and TransportPlant Growth Regulators
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272 questions · page 3 of 14

41. Which of the following process causes substances to move across membranes without the expenditure of cellular energy?

  • A. Endocytosis
  • B. Diffusion
  • C. Active transport
  • D. None of the above

Explanation: The correct answer is Diffusion. Diffusion is characterized by the passive movement of molecules from an area of higher concentration to…

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Correct answer: Diffusion

42. The movement of water molecules from a region of higher water potential to a region of lower water potential through a semi-permeable membrane is referred to:

  • A. Active transport
  • B. Osmosis
  • C. Diffusion
  • D. Photosynthesis

Explanation: Osmosis, the correct answer, refers to the movement of water molecules from an area of higher water potential to an area of lower water…

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Correct answer: Osmosis

43. Four plants are present in different environmental conditions. Plant A is present in a warm climate with continuous rainfall, plant B is present in a cool forest, plant C is present in a warm climate with little breeze, while plant D is present in a warm climate with high wind speed. Which one of the above plants will have the highest rate of transpiration?

  • A. Plant B
  • B. Plant D
  • C. Plant A
  • D. Plant C

Explanation: When it comes to questions like these, do not confuse the option letter with the letter of the plant itself.

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Correct answer: Plant D

44. Widely accepted theory that explains transport of organic solutes in plants is supported by:

  • A. Pressure flow theory
  • B. Diffusion
  • C. Imbition
  • D. Ascent of sap

Explanation: The widely accepted theory that explains the transport of organic solutes in plants is the Pressure Flow Theory, also known as the Mass…

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Correct answer: Pressure flow theory

45. Which organ of a plant has functions of anchoring, storage of food, absorbing water, and minerals:

  • A. Shoot
  • B. Leaves
  • C. Flowers
  • D. Root

Explanation: The root anchors the plant in the soil, absorbs water and minerals, and also stores food in some plants like carrots and radishes.

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Correct answer: Root

46. The hormone(s) synthesised in the meristematic tissue of the plant shoot and root is/ areI. Abscisic acidII. AuxinIII. Cytokinin

  • A. I only
  • B. II only
  • C. I and II
  • D. II and III

Explanation: The correct answer is D. II and III. Both auxin and cytokinin are hormones synthesized in meristematic tissues of plants.

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Correct answer: II and III

47. The given diagram shows a stem tendril helping a plant to climb up a support.The type of growth movement exhibited by the plant is

  • A. Epinasty
  • B. Nutation
  • C. Hyponasty
  • D. Nyctinasty

Explanation: Nutation is a type of growth movement where a plant part, such as a stem or tendril, exhibits revolving or spiraling motion.

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Correct answer: Nutation

48. Auxins and gibberellins are plant hormones. The common role of these hormones is to

  • A. Delay both bud initiation and leaf senescence
  • B. Promote both bud initiation and leaf senescence
  • C. Promote bud initiation and delay leaf senescence
  • D. Promote leaf senescence and delay bud initiation

Explanation: The correct answer is that auxins and gibberellins promote bud initiation and delay leaf senescence.

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Correct answer: Promote bud initiation and delay leaf senescence

49. The given diagrams, I and II, show the growth of a plant without and with hormone treatment. Based on the shown effect in diagram II, the hormones used in the mixture must be

  • A. Ethene and Auxin
  • B. Auxin and Gibberellin
  • C. Abscisic acid and Ethene
  • D. Gibberellin and Abscisic acid

Explanation: The correct answer is Option B: auxin and gibberellin. These two hormones are known to promote plant growth by stimulating cell elongation…

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Correct answer: Auxin and Gibberellin

50. Consider the given diagram. The phenomenon which induces the growth of plant I is

  • A. Vernalization
  • B. Seed dormancy
  • C. Photoperiodism
  • D. Seed germination

Explanation: The correct answer is Vernalization . Vernalization is a process in which the prolonged exposure to cold temperatures triggers the…

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Correct answer: Vernalization

51. The option that identifies the plant's response provoked by red and blue light is

  • A. Red light enhances cell division, blue light promotes cell elongation
  • B. Red light promotes cell elongation, blue light enhances cell division
  • C. Red light enhances cell division, blue light retards cell enlargement
  • D. Red light promotes cell elongation, blue light retards cell division

Explanation: The correct answer is that red light enhances cell division, and blue light promotes cell elongation.

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Correct answer: Red light enhances cell division, blue light promotes cell elongation

52. The given diagram shows the histology of a developing shoot of a plant.The labelled structure gives rise to

  • A. Bark
  • B. Leaves
  • C. Lateral shoots
  • D. Vascular cambium

Explanation: Leaf Primordia: These are young leaf tissues that form on the flanks of the SAM and will develop into mature leaves.

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Correct answer: Leaves

53. Roots exhibit negative phototropism.To demonstrate the reason of this phenomenon, the roots of a potted plant are placed parallel tothe soil. The result shows that auxin gathers in the

  • A. lower half of the root and stimulates growth.
  • B. lower half of the root and slows down the growth.
  • C. upper half of the root and slows down the growth.
  • D. Upper half of the root and stimulates growth

Explanation: In a root placed horizontally, the bottom side contains more auxin and grows less, causing the root to move away from light.

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Correct answer: lower half of the root and slows down the growth.

54. The hormone used commercially to delay the process of ripening and to improve the storagelife of bananas and grapefruits is

  • A. Auxin
  • B. Gibberellin
  • C. Cytokinin
  • D. Ethene

Explanation: Gibberellin is the correct answer because it is a plant hormone that plays a critical role in the ripening process of fruits.

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Correct answer: Gibberellin

55. Long-day plants normally do not flower during the winters.Horticulturalists can trigger the process of flowering in a long-day plant during winters by

  • A. Keeping the plant warm during the night-time
  • B. Exposing the plant to a light source during the night
  • C. Covering the plant with a black cloth for 12 hours a day
  • D. Covering the plant with a transparent plastic during the daytime

Explanation: Long-day plants require a certain length of daylight to trigger flowering.

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Correct answer: Exposing the plant to a light source during the night

56. All of the following are methods to break the seed dormancy EXCEPT

  • A. Exposing the seeds to heat
  • B. Treating the seed coats with acid
  • C. Keeping the seed coats hard and dry
  • D. Giving low temperature treatment to seeds

Explanation: The only option that does not break dormancy is keeping the seed coats hard and dry, hence option C is correct.To break seed dormancy…

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Correct answer: Keeping the seed coats hard and dry

57. Biennials and perennial plants are stimulated to produce flowers by exposing them to low temperature. In these plants, the low temperature stimulus is received by the I. Shoot apex of a mature stem II. Embryo of the seed III. Leaves

  • A. I only
  • B. I and II
  • C. III only
  • D. II and III

Explanation: Only option I and II are correct as In many biennials (e.g., carrot, beet) and some perennials, the shoot apical meristem is the site…

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Correct answer: I and II

58. The experimental set-up that is used MAINLY to demonstrate positive geotropism in plants is

  • A. A
  • B. B
  • C. C
  • D. D

Explanation: Only option B shows positive geotropism as pea seedling growing in a porous pot and sand, with roots growing downwards demonstrates…

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Correct answer: B

59. A farmer wants to ripen the raw apples in his farm. For this purpose, he keeps the raw apples with the apples that are already ripened.The hormone produced by the ripened apples is

  • A. Auxin
  • B. Ethylene
  • C. Cytokinin
  • D. Gibberellin

Explanation: The correct answer is Option B, also known as ethylene, is a plant hormone that is crucial in the ripening of fruits.

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Correct answer: Ethylene

60. During seed dormancy, seeds do not germinate because the seeds

  • A. Are devoid of all kinds of nutrients
  • B. Could produce fruits with hard fruit wall
  • C. Require a period of rest before germination
  • D. Could produce plants that are vulnerable to diseases

Explanation: The correct answer is that seeds require a period of rest before germination (Option C).

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Correct answer: Require a period of rest before germination
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