Question

Secondary metabolites such as nicotine, strychnine and caffeine are produced by plants for their

• A. defense action
• B. effect on reproduction
• C. nutritive value
• D. growth response

Answer 1

The correct option is A

defense action

The correct option is A.

Explanation of the correct option:

Option A:

1. Chemicals such as nicotine, strychnine, and caffeine are used by plants for protection against active grazers and browsers.
2. Caffeine can cause an increase in blood pressure and arrhythmia (irregular heartbeat) in animals.
3. Strychnine can lead to poisoning in animals, leading to toxicosis, tremors, seizures, respiratory arrest, etc.
4. Nicotine is known to increase heart rate and abnormal heart rate, tremors, muscle weakness, etc., in animals.
5. Hence, all these secondary metabolites are used by plants for defense action.

Explanation of the incorrect options:

Option B:

1. Secondary metabolites do not affect the reproduction of plants.
2. Hence, this is an incorrect option.

Option C:

1. Chemicals like caffeine, strychnine, and nicotine add no nutritive value to plants.
2. Thus, this is an incorrect option.

Option D:

1. There are different phytohormones that help to induce a growth response in plants.
2. Therefore, it is an incorrect option.

Final answer: Secondary metabolites such as nicotine, strychnine, and caffeine are produced by plants for their defense action.