Question

The haemolymph (blood) of a cockroach ___________________.
A. Is composed of colourless plasma and numerous types of haemocytes
B. Is homologous to the blood of vertebrates
C. Both (a) and (b)
D. Lack plasma membrane

Answer 1

Hint:- Haemolymph in cockroaches is colourless and its functions and composition are opposite to human blood which is pigmented. The opposite nature of haemolymph shows the analogous behaviour of the haemolymph of arthropods to the blood of vertebrates.

Complete step-by-step solution:-
In humans the blood is involved in the transportation of oxygen and carbon dioxide, along with some nutrients and hormones required to various body parts. The human blood is pigmented and is red in colour due to the presence of the haemoglobin which imparts the red colour to it.
The blood of cockroaches which belong to the phylum arthropod is colourless due to the absence of any pigment in it and is known as haemolymph. Its composition includes proteins, carbohydrates, water, and inorganic substances.
The function of hemolymph in arthropods is to transport nutrients to the body and to remove the waste products from the body. The function of transporting the gases is not done by haemolymph, but has a specialized organ called trachea to exchange oxygen and carbon dioxide with the environment.
Hemolymph contains a special type of cells known as haemocytes which are present as free floating bodies or attached to the tract of inner linings such as the digestive tract, which on entry of foreign bodies or pathogens can be mobilized.

Thus the correct option is C, i.e. both (a) and (b).

Note:-
The arthropods have an open circulatory system, they don’t have vessels and veins to carry the blood to various organs of the body along with the nutrients and the gases mixed in them. It flows freely in the body of an arthropod. The major function of the haemolymph is to lubricate the internal organs and to pass on the nutrients wherever required.