A biologist studied the population of rats in a barn. He found that the average natality was 250, average mortality 240, immigration 20 and emigration 30. The net increase in population is

1. 10         

2. 15           

3. 05           

4. zero

Which one of the following is categorised as a parasite in true sense?

Study the four statements (1-4) given below and select the two correct ones out of them.

(1) A lion eating a deer and a sparrow feeding on grain are ecologically similar in being

consumers

(2) Predator star fish Pisaster helps in maintaining species diversity of some invertebrates

(3) Predators ultimately lead to the extinction of prey species

(4) Production of chemicals such as nicotine, strychnine by the plants are metabolic

disorders

The two correct statements are

1. (2) and (3)               

2. (3) and (4)

3. (1) and (4)               

4. (1) and (2)

A country with a high rate of population growth took measures to reduce it. The figure below shows age sex pyramids of populations. A and B twenty years apart. Select the correct interpretation about them.

Interpretations

1. 'A' is more recent and shows slight reduction in the growth rate

2. 'B' is earlier pyramid and shows stabilized growth rate

3. 'B' is more recent showing that population is very young

4. 'A' is the earlier pyramid and no change has occured in the growth rate  

The formula for exponential population growth is :-

1. dt/dN = rN

2. dN/rN = dt

3. rN/dN = dt

4. dN/dt = rN

Commensalism is an association of two species in which

1. one lives, attached to the other, without harming it

2. both organisms derive benefits from each other

3. one derives its nutrition from the other

4. none of the above

Which one of the following is a matching pair of certain organism(s) and the kind of

association?

1. Shark and sucker fish - predation

2. Algae and fungi in lichens - mutualism

3. Orchids growing on trees - parasitism

4. Cuscuta (dodder) growing in other flowering plants - epiphytism 

Monarch butterfly escapes from predators by

1. foul smell                     

2. bitter taste

3. colour combination         

4. rough skin

Which is correctly labelled with respect to the given diagram?

1. B: Logistic curve

2. C: Carrying capacity

3. C: Exponential curve

4. A: Carrying capacity

Which of the following associations shows mutualism?

1. Fig and wasp         

2. Barnacles on whale

3. Roundworms in human intestine

4. Orchids on mango tree