Question

Which of the following happens in the common cockroach?

• A. Malpighian tubules are excretory organs projecting out from the colon.
• B. Oxygen is transported by haemoglobin in blood.
• C. Nitrogenous excretory product is urea.
• D. The food is ground by mandibles and gizzard.

Answer 1

The correct option is D The food is ground by mandibles and gizzard.

1. Excretion in cockroach takes place through 100-150 yellow coloured thin filamentous Malphigian tubules. They help in removal of excretory products from haemolymph.

2. Oxygen transport in cockroach is a function of Tracheal system and is independent of circulation of blood which lacks haemoglobin.

3. The nitrogenous excretory product in cockroach is uric acid and not urea.

4. The cockroach uses its mandibles for holding and biting the food particles while gizzard is specialised in grinding.

So, the correct option is 'Malpighian tubules are excretory organs projecting out from the colon'.