Correct statement is

Options

A. Arachidonic acid is a saturated fatty acid.
B. Many secondary metabolites have ecological importance.
C. without metabolism there can not be equilibrium.
D. Living organism can not trap the energy, liberated in metabolic reactions.

Answer

To determine which statement is correct, let's analyze each option one by one:

1. **Statement A: Arachidonic acid is a saturated fatty acid.**
- Arachidonic acid is a fatty acid that contains 20 carbon atoms, including the carboxyl carbon. It is classified as an unsaturated fatty acid because it contains carbon-carbon double bonds. Therefore, this statement is **incorrect**.

2. **Statement B: Many secondary metabolites have ecological importance.**
- Secondary metabolites are organic compounds that are not directly involved in the normal growth, development, or reproduction of an organism. However, they can have significant ecological roles, such as providing defense against herbivores or pathogens. For example, some cyanobacteria produce toxins that can be used as herbicides or insecticides. This statement is **correct**.

3. **Statement C: Without metabolism, there cannot be equilibrium.**
- Living organisms typically avoid equilibrium through metabolic processes. Metabolism allows organisms to maintain homeostasis and adapt to their environment. Thus, this statement is **incorrect**.

4. **Statement D: Living organisms cannot trap the energy liberated in metabolic reactions.**
- Living organisms can indeed trap energy, particularly through processes like photosynthesis, where they convert light energy into chemical energy. This statement is therefore **incorrect**.

Based on the analysis above, the correct statement is **B: Many secondary metabolites have ecological importance**.