When does the growth rate of a population following the logistic model equal zero? The logistic model is given as dN/dt = rN(1-N/K)

(1) when N nears the carrying capacity of the habitat

(2) when N/K equals zero

(3) when death rate is greater than birth rate

(4) when N/K is exactly one

Gause's principle of competitive exclusion states that

In which of the following interactions both partners are adversely affected?

(1) Competition

(2) Predation

(3) Parasitism

(4) Mutualism

Most animals are tree dwellers in a 

1. coniferous forest

2. thorn woodland

3. temperate deciduous forest

4. tropical rainforest

The following graph depicts changes in two populations (A and B) of herbivores in grassy field. A possible reason for these changes is that

1. both plant populations in this habitat decreased

2. population-B competed more successfully for food than population-A

3. population-A produced more offspring than population-B

4. population-A consumed the members of population-B

Just as a person moving from Delhi to Shimla to escape the heat for the duration of hot

summer, thousands of migratory birds from Siberia and other extremely cold Northern

regions move to

1. Western Ghat               

2. Meghalaya

3. Corbett National Park     

4. Keoladeo National Park

Consider the following four conditions (I-IV) and select the correct pair of them as adaptation to environment in desert lizards.
The conditions:
I.  Burrowing in soil to escape high temperature
II. Losing heat rapidly from the body during high temperature
III. Bask in sun when temperature is low
IV. Insulating body due to thick fatty dermis

1. (I) and (III)
2. (II) and (IV)
3. (I) and (II)
4. (III) and (IV)

What type of human population is represented by the following age pyramid?

1. Stable population

2. Declining population

3. Expanding population

4. Vanishing population

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)