Question

Determine the correctness or otherwise of the following Assertion [a] and the Reason [r]. Assertion [a]: Endospore can survive heat that would rapidly kill vegetative cells of the same species.
Reason [r]: In endospore, the protoplasm is reduced to minimum volume as a result of the accumulation of calcium-dipicolinic acid complexes and small acid-soluble spore proteins, which forms a cytoplasmic gel and a thick cortex.

• A. Both [a] and [r] are true and [r] is the correct reason for [a]
• B. Both [a] and [r] are true and [r] is not the correct reason for [a]
• C. Both [a] and [r] are false
• D. [a] is true but [r] is false

Hint:

Endospore resistance is mainly due to calcium-dipicolinate, SASPs, dehydration, and protective layers. These adaptations allow spores to survive harsh conditions for years.

Answer 1

The Correct Option is A

Step 1: Assertion check
Endospores (e.g., Bacillus, Clostridium) are highly resistant structures that withstand heat, radiation, and desiccation. Vegetative cells of the same species are heat-sensitive and die rapidly. Hence, Assertion [a] is true. Step 2: Reason check
Heat resistance is conferred by:
High levels of calcium-dipicolinic acid (Ca-DPA) in the core, stabilizing DNA and proteins.
Small acid-soluble spore proteins (SASPs) that bind DNA, protecting it from denaturation.
Low water content in the spore core, forming a cytoplasmic gel.
Thick cortex + protective spore coat.
Thus, Reason [r] is also true and directly explains why spores survive heat.
Therefore, both [a] and [r] are true and [r] correctly explains [a].