Question

Given below are two statements:
Statement I: Ammmonia, urea, and uric acid are principal nitrogenous excretory products formed by animals.
Statement II: The number of malpighian tubules in insects can range from 2 in coccids, to about 250 in some insects.
In light of the above statements, choose the correct answer from the options given below:

• A. Both Statement I and Statement II are correct
• B. Both Statement I and Statement II are incorrect
• C. Statement I is correct but Statement II is incorrect
• D. Statement I is incorrect but Statement II is correct

Hint:

Nitrogenous wastes (ammonia, urea, uric acid) are common across the animal kingdom. In insects, the number of excretory Malpighian tubules varies from 2 in scale insects up to 250 in larger, active insects.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Nitrogenous waste excretion is an essential physiological process in animals.
Insects utilize Malpighian tubules as their primary excretory organs, and their anatomy varies significantly among different species.

Step 2: Detailed Explanation:
Let us evaluate both statements:
- Statement I: The catabolism of proteins and nucleic acids produces nitrogenous wastes.
Ammonia, urea, and uric acid are the three primary end-products of this metabolism across the animal kingdom.
Insects are primarily uricotelic, excreting uric acid to conserve water. Thus, Statement I is correct.
- Statement II: The number of Malpighian tubules varies greatly across different insect groups.
Scale insects (coccids) have only 2 tubules.
Other insects (such as Orthopterans or Hymenopterans) can have up to 150 to 250 tubules suspended in their hemolymph.
Some species (like Collembola and aphids) lack them entirely. Thus, Statement II is correct.
Therefore, both Statement I and Statement II are correct.

Step 3: Final Answer
The correct option is (A).