Consider the following statements conerning food chains
(i) Removal of 80% tigers from an area resulted in greatly increased growth of vegetation
(ii) Removal of most of the carnivores resulted in an increased population of deers
(iii) The length of food chains is generally limited to 3 - 4 trophic levels due to energy loss
(iv) The length of food chains may vary from 2 to 8 trophic levels
Which two of the above statements are correct?

Options

A. (i), (ii)
B. (ii), (iii)
C. (iii), (iv)
D. (i), (iv)

Answer

To determine which two statements concerning food chains are correct, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Analyze Statement (i)**: "Removal of 80% tigers from an area resulted in greatly increased growth of vegetation."
- This statement is **incorrect**. The removal of a significant number of tigers (which are apex predators) would lead to an increase in the deer population. As deer graze on vegetation, their increased numbers would actually result in decreased growth of vegetation, not increased.

2. **Analyze Statement (ii)**: "Removal of most of the carnivores resulted in an increased population of deers."
- This statement is **correct**. Carnivores, such as tigers, prey on herbivores like deer. If most carnivores are removed, the pressure on deer populations is reduced, leading to an increase in their numbers.

3. **Analyze Statement (iii)**: "The length of food chains is generally limited to 3 - 4 trophic levels due to energy loss."
- This statement is **correct**. Food chains are typically limited to 3 to 4 trophic levels because energy decreases significantly at each level due to energy loss in the form of heat and metabolic processes. Beyond 4 levels, there may not be enough energy to support additional levels.

4. **Analyze Statement (iv)**: "The length of food chains may vary from 2 to 8 trophic levels."
- This statement is **incorrect**. While food chains can theoretically have more than 4 levels, in practice, they rarely exceed 4 levels due to the significant energy loss at each trophic level. Therefore, food chains typically vary from 2 to 4 levels.

### Conclusion:
Based on the analysis, the two correct statements are:
- Statement (ii): "Removal of most of the carnivores resulted in an increased population of deers."
- Statement (iii): "The length of food chains is generally limited to 3 - 4 trophic levels due to energy loss."

Thus, the correct answer is **(ii) and (iii)**.

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