arrow_backBack to Study Resources

Quiz Chapter 5: Response in Plants

10 questions ยท Form 5 Biology Bab 5: Response in Plants

Question 1 of 10Score: 0

Which phytohormone is a gas that accelerates fruit ripening?

Full Question List & Answer Key

Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.

1. Which phytohormone is a gas that accelerates fruit ripening?

  1. Ethylene
  2. Cytokinin
  3. Gibberellin
  4. Indole-3-acetic acid
Show answer

Answer: A

Ethylene is a unique gaseous phytohormone that promotes enzymatic breakdown of starches and fruit ripening.

2. What effect does gibberellin application have on commercial table grape crops?

  1. Produces small, tightly packed, sour berries
  2. Increases internode/pedicel length and produces larger, well-spaced grapes
  3. Causes immediate leaf loss and fruit drop
  4. Prevents fruit formation completely
Show answer

Answer: B

Gibberellin application elongates fruit stalks (pedicels), giving individual grapes more room to grow larger without overcrowding.

3. Which phytohormone works in combination with auxin to regulate cell division and organ differentiation in tissue culture?

  1. Abscisic acid
  2. Cytokinin
  3. Ethylene
  4. Gibberellin
Show answer

Answer: B

The ratio of cytokinin to auxin in tissue culture media determines whether undifferentiated callus cells develop into roots or shoots.

4. What type of response is shown by the sudden folding of Mimosa pudica leaflets when touched?

  1. Positive Thigmotropism
  2. Seismonastic / Thigmonastic response
  3. Negative Geotropism
  4. Photonastic response
Show answer

Answer: B

The rapid folding of Mimosa leaves is a non-directional, reversible seismonastic response caused by sudden loss of turgor pressure in pulvinus cells.

5. Which phytohormone induces rapid stomatal closure in response to severe drought stress?

  1. Gibberellin
  2. Abscisic acid (ABA)
  3. Auxin (IAA)
  4. Cytokinin
Show answer

Answer: B

Abscisic acid acts as a plant stress hormone that signals guard cells to lose turgor pressure, closing stomata to conserve water.

6. Which plant organ demonstrates POSITIVE geotropism and POSITIVE hydrotropism?

  1. Shoot tip
  2. Flower petal
  3. Root tip
  4. Leaf lamina
Show answer

Answer: C

Roots grow downward toward gravity (positive geotropism) and toward water sources in soil (positive hydrotropism).

7. Which phytohormone delays leaf senescence (aging) by keeping leaves green longer?

  1. Cytokinin
  2. Abscisic acid
  3. Ethylene
  4. Synthetic 2,4-D
Show answer

Answer: A

Cytokinins delay leaf aging (senescence) by promoting nutrient mobilization and maintaining protein/chlorophyll stability.

8. What causes the reversible folding of leaves in leguminous plants at dusk (nyctinasty)?

  1. Cell division in the apical meristem
  2. Changes in turgor pressure in pulvinus joint cells at the leaf base
  3. Rapid synthesis of lignin in petiole cell walls
  4. Irreversible cell elongation on the upper leaf surface
Show answer

Answer: B

Nyctinastic sleep movements are regulated by reversible osmotic water loss and turgor changes in specialized pulvinus cells.

9. What phenomenon occurs when a main apical shoot tip suppresses the growth of lateral side buds?

  1. Apical dominance
  2. Parthenocarpy
  3. Senescence
  4. Photoperiodism
Show answer

Answer: A

Apical dominance is driven by high auxin produced at the apical tip diffusing downward to inhibit axillary bud growth.

10. How does auxin (IAA) distribution change when a shoot tip receives unilateral light?

  1. Auxin breaks down completely under light.
  2. Auxin diffuses laterally to accumulate on the shaded side of the shoot tip.
  3. Auxin concentrates exclusively on the illuminated side.
  4. Auxin moves into root tissues via active transport.
Show answer

Answer: B

Unilateral light causes auxin to migrate laterally away from light to the shaded side, promoting faster cell elongation on that side.

Sponsored