Question

Given below are two statements :
one is labelled as
Assertion (A) and the other is labelled as
Reason (R).
Assertion (A) :
Biodiversity is normally greater in the lower latitudes as compared to the higher latitudes.
Reason (R) :
Along the mountain gradients, biodiversity is normally greater in the lower altitudes as compared to the higher altitudes.
In the light of the above statements, choose the most appropriate answer from the options given below :

• A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
• B. Both (A) and (R) are correct but (R) is not the correct explanation of (A)
• C. (A) is correct but (R) is not correct
• D. (A) is not correct but (R) is correct

Hint:

Remember:
• Lower latitude (Tropics) \(\rightarrow\) Higher biodiversity
• Lower altitude \(\rightarrow\) Higher biodiversity \[ \text{Tropical rainforests possess the highest biodiversity on Earth} \]

Answer 1

The Correct Option is B

Concept: Biodiversity generally follows predictable ecological patterns across the Earth. Two important biodiversity patterns are:
• Latitudinal diversity gradient
• Altitudinal diversity gradient Species richness is usually:
• Higher in tropical regions (lower latitudes)
• Lower toward polar regions (higher latitudes) Similarly, biodiversity tends to decrease with increasing altitude along mountain slopes.

Step 1: Evaluating Assertion (A). The assertion states: \[ \text{Biodiversity is greater at lower latitudes} \] This statement is correct because tropical regions near the equator possess:
• Stable climate
• High productivity
• Longer evolutionary history Therefore: \[ \boxed{(A) \text{ is correct}} \]

Step 2: Evaluating Reason (R). The reason states: \[ \text{Biodiversity is greater at lower altitudes than higher altitudes} \] This statement is also correct. At higher altitudes:
• Temperature decreases
• Oxygen availability decreases
• Environmental conditions become harsher Hence biodiversity generally declines with altitude. Thus: \[ \boxed{(R) \text{ is correct}} \]

Step 3: Determining whether (R) explains (A). Although both statements are true:
• Assertion refers to latitude
• Reason refers to altitude The reason does not directly explain the latitudinal biodiversity gradient. Therefore: \[ \boxed{(R) \text{ is not the correct explanation of } (A)} \] Hence, the correct answer is: \[ \boxed{(B)\ \text{Both (A) and (R) are correct but (R) is not the correct explanation of (A)}} \]