CBSE Class 10 Science 2023: question 35(a)
Set in the CBSE Class 10 board exam of 2023, paper 31/2/1, section D, question 35(a), for 5 marks. Try it first; the hints and our step-by-step solution are below.
Q35(a) · 5 marks · Long answerControl and Coordination
(i) List three points of difference between nervous and hormonal mechanisms for control and coordination in animals.
(ii) How are auxins related with the bending of plant shoot towards unidirectional light ? Explain.
Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 31/2/1.
Hints
Open one hint at a time and try again before the next.
Hint 1
Compare how the message is carried, the route it takes, and how fast and long the response is.
Hint 2
Auxin is made at the shoot tip. Which side of the shoot does it move to when light comes from one side?
Hint 3
If one side of a stem grows faster than the other, which way will the stem bend?
Step-by-step solution
Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.
- 1 mark
(i) Difference 1 (nature of message): In nervous control, information travels as electrical impulses. In hormonal control, it is carried as chemical messengers (hormones).
- 1 mark
(i) Difference 2 (route): Nerve impulses travel along neurons. Hormones are carried by the blood to their target organs.
- 1 mark
(i) Difference 3 (speed and duration): Nervous responses are rapid and short-lived. Hormonal responses are slow but long-lasting.
- 1 mark
(ii) When a growing shoot receives light from one side, auxin, a growth hormone made at the shoot tip, moves towards the shaded side of the shoot.
- 1 mark
(ii) The higher auxin concentration makes the cells on the shaded side elongate faster than those on the lit side. So the shoot bends towards the light (positive phototropism).
Answer: (i) Electrical impulse vs chemical hormone; via neurons vs via blood; rapid and short-lived vs slow and long-lasting. (ii) Auxin moves to the shaded side, causing faster growth there, so the shoot bends towards light.
Where the marks are
- Any three correct differences between nervous and hormonal control (1 mark each, 3 marks)
- Auxin shifts towards the shaded side under unidirectional light (1 mark)
- More growth on the shaded side bends the shoot towards light (1 mark)
Revise the chapter
- Chapter: Control and Coordination (notes, formulas, where marks are lost and every past question)
More questions from Control and Coordination
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- 2023 board paper, set 31/4/1, Q22(A) · 2 marksName the part of brain which is responsible for the following actions :
- 2023 board paper, set 31/4/1, Q22(B) · 2 marksWhere are auxins synthesized in a plant ? Which organ of the plant shows :
The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.