Biomagnification refers to increase in concentration of the toxicant at successive trophic levels, this happens because

Options

A. A toxic substance accumulated by an organism can not be metabolised
B. A toxic substance accumulated by an organism can not be excreted
C. A toxic substance passed on to the next higher trophic level
D. All of the above.

Answer

**Step-by-Step Solution:**

1. **Understanding Biomagnification**: Biomagnification is the process where the concentration of toxic substances increases in organisms at each successive trophic level in a food chain. This means that as you move up the food chain, the amount of toxins in the organisms becomes higher.

2. **Accumulation of Toxic Substances**: The primary reason for biomagnification is that certain toxic substances, such as heavy metals or persistent organic pollutants, accumulate in the bodies of organisms. These substances are not easily broken down or metabolized by the organisms.

3. **Inability to Excrete Toxins**: Many of these toxic substances cannot be excreted efficiently by the organisms. As a result, they build up in the tissues over time. This accumulation occurs because the rate of intake of the toxic substance exceeds the rate at which it can be eliminated.

4. **Transfer to Higher Trophic Levels**: When a predator consumes prey that has accumulated toxins, the predator absorbs these toxins. Since the toxins are not metabolized or excreted, they become more concentrated in the predator's body. This process continues as each successive trophic level consumes organisms from the level below.

5. **Conclusion**: Therefore, biomagnification occurs due to the accumulation of toxic substances that cannot be metabolized or excreted, leading to higher concentrations at each trophic level.

**Final Answer**: Biomagnification refers to the increase in concentration of toxic substances at successive trophic levels because these substances accumulate in organisms, cannot be metabolized, and are passed on to the next higher trophic level.

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