Which one of the following statement is incorrect regarding the population interactions?

Options

A. In amensalism one species is harmed and other is benefited.
B. Commensalism is the interaction in which one species benefits and the other is neither harmed nor benefited
C. The association of cattle egret and grazing cattle is a classic example of commensalism.
D. Competition occurs when closely related species complete for the same resources.

Answer

To determine which statement is incorrect regarding population interactions, we need to analyze each statement provided in the question.

### Step-by-Step Solution:

1. **Understanding the term "Mensalism":**
- Mensalism is a type of population interaction where one species is harmed while the other is neither benefited nor harmed.
- Example: Penicillium fungus inhibits the growth of Staphylococcus bacteria without gaining any benefit from it.

**Hint:** Remember that in mensalism, one species is harmed and the other is neutral.

2. **Evaluating the first statement:**
- The first statement claims that in mensalism, one species is harmed and the other is benefited.
- This is incorrect because, by definition, mensalism does not allow for one species to benefit; it is a negative-zero interaction.

**Hint:** Check the definitions of the interactions carefully to spot inaccuracies.

3. **Analyzing the second statement (Commensalism):**
- Commensalism is defined as an interaction where one species benefits while the other is neither harmed nor benefited.
- Example: Pilot fish benefit from the shark by eating leftover food, while the shark is unaffected.

**Hint:** Commensalism involves one benefiting and the other being neutral.

4. **Evaluating the third statement (Cattle Egret and Grazing Cattle):**
- This statement describes the relationship between cattle egret and grazing cattle as an example of commensalism.
- The cattle egret benefits by feeding on insects disturbed by the grazing cattle, while the cattle are unaffected.

**Hint:** Look for examples of interactions to reinforce your understanding.

5. **Understanding the fourth statement (Competition):**
- Competition typically occurs when closely related species compete for the same resources.
- While it is common for closely related species to compete, competition can also occur between unrelated species.

**Hint:** Competition can be between related or unrelated species, so be careful with generalizations.

6. **Conclusion:**
- The first statement is incorrect regarding population interactions because it misdefines mensalism. Therefore, the answer to the question is that the first statement is the incorrect one.

### Final Answer:
The incorrect statement regarding population interactions is the first one, which claims that in mensalism, one species is harmed and the other is benefited.