Read the passage carefully and give the answers to the next five questions:

Does the number of species in a community really matter to the functioning of the ecosystem? This is a question for which ecologists have not been able to give a definitive answer. For many decades, ecologists believed that communities with more species, generally, tend to be more stable than those with less species. According to the International Union for Conservation of Nature and Natural Resources (IUCN) (2004), the total number of plant and animal species described so far is more than 1.5 million.

Among the vertebrates, which of the following is the most species-rich group?

Fishes

The correct answer is Option (2) – Fishes

More than 70 per cent of all the species recorded are animals, while plants (including algae, fungi, bryophytes, gymnosperms and angiosperms) comprise no more than 22 per cent of the total. If we classify the animals into vertebrates and invertebrates, then insects show maximum species diversity amongst invertebrates and fishes (Pisces) show maximum diversity amongst vertebrates, followed by birds (Aves), reptiles (class Reptilia) and mammals (class Mammalia).