Science — CBSE Class 10 board question

(i) Differences between Nervous and Hormonal Mechanisms:

| Nervous Mechanism | Hormonal Mechanism |
|---|---|
| Information transmitted as electrical impulses | Information transmitted as chemical hormones through blood |
| Response is very fast | Response is slow |
| Effect is short-lived | Effect is long-lasting |

(ii) Auxins and Phototropism:

Auxins are plant hormones produced at the shoot tip. When light falls from one side (unidirectional), auxins migrate to the shaded (darker) side of the shoot.

The higher concentration of auxins on the shaded side causes cells there to elongate faster than cells on the illuminated side. This unequal growth causes the shoot to bend towards the light source.

This bending movement is called phototropism, and it is a positive phototropic response — the shoot grows in the direction of light.

Source: Chapter 7 — Control and Coordination

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• For part (i), examiners expect three clear points as a table or parallel list. Common accepted points: speed of response, duration of effect, medium of communication (electrical vs. chemical), localised vs. widespread effect.
• For part (ii), the key steps are: auxin production at tip → migration to shaded side → differential cell elongation → bending toward light. Missing "differential elongation" loses a mark. Name the response as phototropism for full credit.
• The source passages provided are unrelated (Chemistry/Physics chapters), so this answer is based on the standard NCERT Chapter 7 Biology content, which is the prescribed source for this topic.