Question

Blood of cockroach does not contain haemoglobin because
A. It respires through the atmosphere.
B. It respires through book lungs.
C. It does not respire.
D. It has some other means to carry oxygen directly into the tissues.

Answer 1

Cockroach is a terrestrial, nocturnal and cosmopolitan insect found in places with warmth, moisture, darkness and plenty of food. It is an omnivorous organism. The blood circulatory system in cockroaches is of open or lacunar type.

Complete answer: Blood of the cockroach is colorless as it has no haemoglobin so is also called hemolymph. It is formed of a transparent liquid called plasma and numerous corpuscles called haemocytes. Blood corpuscles are of two types- circular pro leukocytes and amoeboid phagocytes.
In cockroaches, there are ten pairs of sphincter apertures called spiracles. Each spiracle leads into an atrium from which the main tracheal trunk starts. There are three pairs of tracheal trunks which are interconnected by transverse tracheae.
They have tracheal intercom which is the network of branches formed by the division and redivision of tracheae inside the body. Their finest branches are bronchioles which end into the body cells so oxygen directly goes to the body cells and blood has no role in the transportation of oxygen.
So, the correct answer is “Option D”.

Additional Information: The haemocoel of cockroach is divided into three interconnected chambers- dorsal or pericardial sinus, middle or perivisceral sinus and ventral or perineural sinus.
Heart of the cockroach is elongated, thick, muscular and 13-chambered in the pericardial sinus of the haemocoel. Each chamber represents one heart.
Each chamber of the heart receives oxygenated blood from the dorsal sinus through one pair of slit like apertures called ostia which are valvular apertures.

Note: Cockroaches show tracheal respiration as respiratory structures are ectodermal, branched and silvery white air tubes called tracheae, whose external openings are called spiracles or stigmata.