(A) P, Q

(B) P, R

(C) Q, R

(D) Q, S

Correct Answer

✅ Option (B): P and R

Detailed Explanation

This question tests core concepts of ecology, biodiversity, succession, speciation, and environmental science. Each statement is evaluated below.

Statement P

“Primary succession involving xerosere is initiated in a wet habitat.”
❌ Incorrect

• Xerosere refers to succession that begins in dry habitats (e.g., bare rock, sand).

• Succession starting in wet habitats is called hydrosere.

• Hence, the statement is ecologically incorrect.

✘ Statement P is incorrect.

Statement Q

“Halones commonly found in electronic equipment are one of the active forces destroying the protective ozone layer in the stratosphere.”
✅ Correct

• Halons (bromine-containing compounds) are used in fire extinguishers and electronic equipment.

• They release bromine radicals, which are highly destructive to ozone, even more potent than chlorine.

• This statement is scientifically correct.

✔ Statement Q is correct.

Statement R

“Sympatric speciation occurs when the new species evolves in geographic isolation from the parent species.”
❌ Incorrect

• Sympatric speciation occurs without geographic isolation, within the same area.

• Speciation due to geographic isolation is called allopatric speciation.

• The statement wrongly defines sympatric speciation.

✘ Statement R is incorrect.

Statement S

“α-Diversity is the diversity of species within a habitat or community.”
✅ Correct

• Alpha diversity (α-diversity) refers to species diversity within a particular habitat or ecosystem.

• This is a standard and correct ecological definition.

✔ Statement S is correct.

Why Option (B) Is Correct

• P is incorrect (xerosere does not begin in wet habitats)

• R is incorrect (sympatric speciation does not involve geographic isolation)

• Q and S are correct statements

✔ Therefore, the correct answer is Option (B): P and R.

Quick Exam Memory Tips

• Xerosere → Dry habitat

• Hydrosere → Wet habitat

• Sympatric speciation → No geographic isolation

• Allopatric speciation → Geographic isolation

• α-diversity → Within-habitat diversity

Exam Relevance

🔹 Frequently asked in CSIR-NET Life Sciences
🔹 Important for ecology, biodiversity & environmental biology
🔹 High-yield statement-based MCQs