Q.Which of the following statements is correct?

Let's evaluate each statement to determine the correct one based on ecological principles and common examples.

• Parthenium, also known as carrot grass, is an invasive alien species that arrived in India as a contaminant with imported wheat. It is not endemic to our country.
• The African catfish (Clarias gariepinus) was introduced for aquaculture but poses a significant threat to indigenous catfishes due to its invasive nature, outcompeting and preying on native species. …

Understanding the dynamics of biodiversity, including the threats posed by alien species and the causes of extinction, is crucial for appreciating ecological balance and conservation efforts. Many species face endangerment or extinction due to human activities, often categorized into what is known as the "Evil Quartet" – habitat loss and fragmentation, over-exploitation, alien species invasions, and co-extinctions. This question tests our knowledge of specific examples related to these threats, as outlined in the NCERT biology curriculum.

Let's examine each statement:

• Statement (A): Parthenium is an endemic species of our country.

  Parthenium, also known as carrot grass, is explicitly mentioned in NCERT as an invasive weed species. An endemic species is one that is native or restricted to a particular geographic region. Since Parthenium is an invasive species, it means it was introduced from elsewhere and is not native to our country. Therefore, it cannot be an endemic species. Its introduction has caused significant environmental damage and poses a threat to native species.

• Statement (B): African catfish is not a threat to indigenous catfishes.

  The NCERT textbook clearly states that the illegal introduction of the African catfish (Clarias gariepinus) for aquaculture purposes "is posing a threat to the indigenous catfishes in our rivers." This is a classic example of an alien species invasion where a non-native species outcompetes or preys upon native species, leading to their decline. Thus, the statement that it is not a threat is incorrect.

• Statement (C): Steller's sea cow is an extinct animal.

  NCERT lists Steller's sea cow as a prominent example of a species that has gone extinct due to over-exploitation by humans. Over-exploitation occurs when humans harvest resources at a rate faster than they can replenish, driven by 'greed' rather than 'need'. Along with the passenger pigeon, Steller's sea cow serves as a stark reminder of the devastating impact human activities can have on biodiversity. This statement is correct. …

Check each statement against a specific chapter fact rather than judging them as a group: Parthenium is invasive not endemic; African catfish threatens native catfish; Lantana isn't 'c …