Which of these statements is true about nerve ring?

The fusion of how many segments makes up the head part of cockroach?

Cutaneous respiration in frogs takes place by ___

Where are the calciferous glands of the earthworm present?

Which of these structures is involved in blood circulation in cockroach?

In frogs, the undigested food passes out through the __

Which of the following statements about earthworms is true?

The head of the cockroach is flexible due to a flexible neck. True or false?