Which one of the following is the true description about an animal concerned?
A
Rat - Left kidney is slightly higher in position than the right one
B
Cockroach - 10 pairs of spiracles (2 pairs on thorax and 8 pairs on abdomen)
C
Earthworm - The alimentary canal consists of a sequence of pharynx, oesophagus, stomach, gizzard and intestine
D
Frog - Body divisible into three regions - head, neck and trunk
The answer is B.
Solution
Cockroach: the respiratory system consists of a network of tracheae that open to the outside through 10 pairs of small holes called spiracles, present on the lateral side of the body. Of these, 2 pairs are on the thorax and 8 pairs are on the abdomen. So this description is true. Rat: the right kidney is slightly higher (more anterior) in position than the left one, so the statement given is wrong. Earthworm: the correct sequence of the alimentary canal is buccal cavity, pharynx, oesophagus, gizzard, stomach and intestine. The gizzard comes before the stomach, so the given sequence is wrong. Frog: the body is divisible into head and trunk only; the neck and tail are absent. So the true description is that of the cockroach with 10 pairs of spiracles.
ConceptRespiratory system of cockroach
Cockroach in past papers
4 questions from this chapter have appeared across 4 exam years.
