Question

The plant hormone that activates many defense responses is

• A. Linolenic acid
• B. Shikimic acid
• C. Jasmonic acid
• D. Linoleic acid

Hint:

Jasmonic acid:
- Defense hormone.
- Activates insect and pathogen resistance.
- Synthesized from linolenic acid (octadecanoid pathway).

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
This question tests knowledge of plant hormones and their functions.

Step 2: Detailed Explanation:
Jasmonic acid is a plant hormone that activates many defense responses.
It is involved in:
- Insect herbivory defense.
- Pathogen resistance.
- Wounding response.
- Abiotic stress tolerance.
Linolenic acid (A): Precursor for jasmonic acid synthesis.
Shikimic acid (B): Precursor for aromatic amino acids.
Linoleic acid (D): Fatty acid, not a defense hormone.
Thus, jasmonic acid activates defense responses.

Step 3: Final Answer:
Thus, jasmonic acid activates defense responses, which corresponds to option (C).
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