Water is very essential for life.  Write any three features both for plants and animals, which enable them to survive in water-scarce environment.

3

(a)

How do organisms cope with stressful environmental conditions, which are localised or of short duration?

3

(a)

How do organisms like fungi, zooplanktons and bears overcome the temporary, short-lived climatic stressful conditions?  Explain.

3

(a)

Write a short note on adaptations of desert plants and animals.

3

(a)

Give and example for:
(a) An endothermic animal.
(b) An ectothermic animal.
(c) An organism of benthic zone.

3

(a)

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

3

(a)

Name six major terrestrial biomes of the world.

3

(a)

Describe any three reproductive strategies that organisms have evolved in relation to a particular set of selective pressures.

3

(a)

Competition does not always occur between closely related species for the same resources.  Substantiate the statement with examples.

3

(a)

Mutualism often involves co-evolution of the mutualists.  Describe taking the example of animal plant (wast-fig) relationship.

3

(a)

If the population growing exponentially doubles in size in 3 years, what is the intrinsic rate of increase  (r) of the population?

3

(a)

Distinguish between the following:
(a) Hiberation and aestivation
(b) Ectotherms and endotherms.

3

(a)

Why is the thermoregulation more effective achieved in larger animals than in smaller ones?

3

(a)

(a) Write an equation for Verhulst Pearl logistic Growth where
N = Population density at a time t
r = Intrinsic rate of natural increase
K = Carrying capacity 
(b) Draw a graph for a Population  whose population density has reached the carrying capacity.
(c) Why is the logistic growth model considered a more realistic one for most animal populations?
(d) Draw a growth curve where resources are not limiting to growth of a population.

3

(a)

The range of tolerance to the variations in each environmental factor varies greatly in different species.Name the terms used for species.
(i) Which live in regions of nearly uniform temperature throughout the year and showing narrow range of tolerance to temperature changes.
(ii) Which live in areas where temperature changes significantly at different times of the year and showing wide range of tolerance to temperature changes.

3

(a)