Give one example for each of the following:
(a) Migratory animal    
(b) Predator animal    
(c) Phytophagous animals    
(d) Camouflaged animal    
(e) Chemical defense agent.

Study the graph given below and answer the questions that follow.

(i) Write the status of food and space in the curves A and B.
(ii) In the absence of predators, which one of the two curves would appropriately depict the prey population?
(iii)Time has been shown on X-axis and there is a parallel dotted line above it. Give the significance of this dotted line.

Explain the S-shaped pattern of population growth. How is J-shaped pattern different from it and why?

Why are coral reefs not found in the regions from West Bengal to Andhra Pradesh but are found in Tamil Nadu and on the East coast of India?

Why do all the fresh water organisms have contractile vacuoles whereas majority of marine organisms lack them?

In nature, leeches attach themselves to the cow grazing in the field (shown in figure I). In some medical treatments, doctors attach leeches onto accumulation of blood (shown in figure II).
(i) State the type of interaction in figure I and II.
(ii) Under what conditions the doctors advice leech therapy?
(iii) Why are leeches used for treating patients?

Comment on the following figures: I, II and III. In these, A,B,C,D,G,P,Q,R,S are different species.

What is 'predation'? Explain with the help of suitable examples why is it required in a community with rich biodiversity.

In Lake Tanganyika in Africa, there are six species of fish of the genus Tropheus and a much larger number of distinctly coloured subspecies of each of the six species. Tropheus species are small fishes that are confined to isolated rocky habitats around the shores of Lake Tanganyika.

Recent research has compared DNA sequence data from these various species and subspecies and linked this with geological data on the lake. This suggests that some 1.25 million years ago, when the lake first filled, the six species evolved during the primary radiation phase. They arose from river dwelling ancestors and then filled all available niches. Secondary radiations into the many subspecies occurred during the last 2,00,000 years.
Sometime during this period, the water level in the lake fell, resulting in the formation of three separate lake basins. These basins persisted for level rose again.
 Figure shown above is an outline map of the lake and the location of the three temporary basins caused by lowering of lake levels.
(i) Define the terms
(a) species
(b) niche
(ii) Explain how natural selection could have caused the evolution of the six closely related species in the primary radiation.

In Lake Tanganyika in Africa, there are six species of fish of the genus Tropheus and a much larger number of distinctly coloured subspecies of each of the six species. Tropheus species are small fishes that are confined to isolated rocky habitats around the shores of Lake Tanganyika.

Recent research has compared DNA sequence data from these various species and subspecies and linked this with geological data on the lake. This suggests that some 1.25 million years ago, when the lake first filled, the six species evolved during the primary radiation phase. They arose from river dwelling ancestors and then filled all available niches. Secondary radiations into the many subspecies occurred during the last 2,00,000 years.
Sometime during this period, the water level in the lake fell, resulting in the formation of three separate lake basins. These basins persisted for level rose again.
 Figure shown above is an outline map of the lake and the location of the three temporary basins caused by lowering of lake levels.
(i) Define the terms
(a) species
(b) niche
(ii) Explain how natural selection could have caused the evolution of the six closely related species in the primary radiation.