(a) Explain with the help of a graph, the population growth curve when resources are
(i) limiting and
(ii) not limiting.
(b) 'Nature has a carrying capacity for a species'.  Explain.

With the helps of a suitable diagram describe the logistic population growth curve.

Define the following terms and give one example for each.
(a) Commensalism    
(b) Parasitism    
(c) Camouflage    
(d) Mutualism    
(e) Interspecific competition.

Organisms remain as individuals but interact as a group with other organisms and physical habitats and behave as population, community, ecosystem, etc.
(a) What according to you, are the factors that account for the formation of major biomes?
(b) Name any four major biomes of India.
(c) What value is learnt from this statement?

Water is the most important factor influencing the life of organisms.  Life on earth originated in water and cannot be sustained without water.  Organisms living in water bodies (ocean, lake, river, etc.) also face water-related problems.
(a) How are aquatic animals affected by the quality of water? Explain.
(b) Mention any four adaptations the desert plants have, to live there successfully.
(c) Represent the value learnt.

No species can exist alone in a habitat.  Any species has a minimal requirement of at least one more species, on which it can feed.  Interspecific interactions arise from the interaction of populations of two different species.
(a) What term is given to the interaction, where one species is benefitted and the other is neutral?
(b) Give four examples of the above kind of interaction.
(c) How do you call the interaction where one species is neutral and the other is harmed? Give an example of such an interaction.
(d) What value do you learn from this?

'Struggle for existence and survival of the fittest' is Darwin's theory of Natural selection.  Interspecific competition, a potent force in organic evolution, is generally believed to occur between closely related species for the same resources, that are limiting, but this is not entirely true.
(a) Give an example where totally unrelated species could compete with each other.
(b) Resources need not be limiting for competition to occur.  Justify with an example.
(c) What value is learnt from this?

What is competition? Why it is not true always? Explain competitive release and Gause's competitive exclusive principle. Write contribution of Mac Arthur.

Where would you expect more species biodiversity-in tropics or polar regions? Give reasons in support of your answer.

Give below is a graph depicting organismic response to changing external conditions. According to their response the organisms are grouped into two types. Name the type which will show
(i) pattern A and
(ii) pattern B.