Match each disease with its correct type of vaccine:
(a) tuberculosis            (i) harmless virus
(b) whooping cough     (ii) inactivated toxin
(c) diphtheria              (iii) killed bacteria
(d) polio                     (iv) harmless bacteria

The following graph depicts changes in two
populations (A and B) of herbivores in a grassy field
A possible reason for these changes is that:

Which one of the following statements is wrong?

Secondary Succession takes place on/in:

The hilum is a scar on the :

The guts of cow and buffalo possess: