Question

Which one of the following statements is correct regarding cockroach?

• A. Head is oval in shape
• B. There are 10 pairs of spiracles (2 pairs on thorax and 8 pairs on abdomen)
• C. Heart is differentiated into funnel shaped chambers with setae on either side
• D. Each eye consists of about 1000 hexagonal ommatidia

Answer 1

The correct option is B There are 10 pairs of spiracles (2 pairs on thorax and 8 pairs on abdomen)

Option ‘b’ is correct as there are ten pairs of spiracles or stigmata arranged segmentally: 2 pairs in the thorax and 8 pairs in the abdomen. Each spiracle is a slit-like aperture for the entry and exit of the air to and from the trachea, respectively.

Option ‘a’ is incorrect as the head of the cockroach is triangular in shape and lies anteriorly at right angles to the longitudinal body axis.

Option ‘c’ is incorrect heart of cockroach consists of elongated muscular tube, differentiated into funnel shaped chambers with ostia on either side, not the setae.

Option ‘d’ is incorrect. Dorsally situated compound eyes of cockroaches consists of about 2000 hexagonal ommatidia, not 1000.