Class 10 Chemical Coordination in Plants Mock Test (ICSE)

Topics in Chemical Coordination in Plants

• Plant growth regulators: auxins, gibberellins, cytokinins, abscisic acid and ethylene
• Tropic movements
• Phototropism, geotropism and hydrotropism

Chemical Coordination in Plants practice questions with answers

1. Q1Multiple choice·1 mark
   Roots of plants generally show positive geotropism and:

   1. (a)negative hydrotropism
   2. (b)positive thigmotropism
   3. (c)positive phototropism
   4. (d)negative phototropism
   Show answer and step marks

   1. Correct option: (d) negative phototropism+1

   Answer: (d)
2. Q2Multiple choice·1 mark
   The directional movement of a plant part in response to gravity is called:

   1. (a)Phototropism
   2. (b)Hydrotropism
   3. (c)Thigmotropism
   4. (d)Geotropism
   Show answer and step marks

   1. Correct option: (d) Geotropism+1

   Answer: (d)
3. Q3Multiple choice·1 mark
   Which plant hormone functions as a growth inhibitor and promotes the abscission of leaves and fruits?

   1. (a)Gibberellin
   2. (b)Cytokinin
   3. (c)Auxin
   4. (d)Abscisic acid
   Show answer and step marks

   1. Correct option: (d) Abscisic acid+1

   Answer: (d)
4. Q4Multiple choice·1 mark
   Which plant hormone is primarily responsible for apical dominance in plants?

   1. (a)Gibberellin
   2. (b)Cytokinin
   3. (c)Auxin
   4. (d)Abscisic acid
   Show answer and step marks

   1. Correct option: (c) Auxin+1

   Answer: (c)
5. Q5Long answer·4 marks
   (a) Define hydrotropism. (b) Explain how auxins bring about the bending of a shoot towards a source of unilateral light. (c) State how roots respond to gravity and explain the advantage of this response to the plant.
   Show answer and step marks

   1. (a) Hydrotropism is the directional growth movement of a plant part in response to a moisture or water gradient.+1
   2. (b) Auxins are synthesized at the shoot apex and diffuse downwards; when exposed to unilateral light, auxins migrate towards the shaded side.+1
   3. (b) The higher concentration of auxin on the shaded side stimulates faster cell elongation, causing the shoot to bend towards the light source.+1
   4. (c) Roots show positive geotropism: they grow downwards, towards gravity.+0.5
   5. (c) Advantage: this anchors the plant firmly in the soil and lets the roots reach water and minerals.+0.5

   Answer: (a) Hydrotropism is the growth movement of a plant part in response to water (moisture). (b) Under unilateral light, auxin moves to the shaded side of the shoot; the extra auxin there makes those cells elongate faster, so the shoot bends towards the light. (c) Roots are positively geotropic (grow downwards towards gravity), which anchors the plant and lets the roots reach water and minerals.

More Class 10 Biology mock tests