Mark true or false in the following statements.
(i) Habitat loss and fragmentation is the most important cause driving animals and plants to extinction.
(ii) Steller's sea cow has been extinct due to habitat loss.
(iii) When alien species are introduced deliberated or unintentionally for whatever purpose, some of them turn invasive and cause extinction of indigenous species.
(iv) When a host fish species becomes extinct its unique assemblage of parasites also meets the same fate.

Answer

**Step-by-Step Solution:**

1. **Statement (i):** "Habitat loss and fragmentation is the most important cause driving animals and plants to extinction."
- **Analysis:** This statement is true. Habitat loss and fragmentation significantly impact biodiversity, forcing organisms to relocate. If they cannot adapt to new environments, they face extinction.
- **Conclusion:** True

2. **Statement (ii):** "Steller's sea cow has been extinct due to habitat loss."
- **Analysis:** This statement is false. The extinction of Steller's sea cow was primarily due to overhunting and co-extinction rather than habitat loss.
- **Conclusion:** False

3. **Statement (iii):** "When alien species are introduced deliberately or unintentionally for whatever purpose, some of them turn invasive and cause extinction of indigenous species."
- **Analysis:** This statement is true. Alien species can become invasive, disrupting local ecosystems and leading to the decline or extinction of native species.
- **Conclusion:** True

4. **Statement (iv):** "When a host fish species becomes extinct, its unique assemblage of parasites also meets the same fate."
- **Analysis:** This statement is true. Parasites that rely on a host for survival will also face extinction if their host species disappears, as they lose their source of nutrition.
- **Conclusion:** True

**Final Answers:**
- (i) True
- (ii) False
- (iii) True
- (iv) True

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