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

1.	Human foetus developing inside the uterus draws nourishment from the mother
2.	Head louse living on the human scalp as well as laying eggs on human hair
3.	The cuckoo (koel) lays its eggs in a crow's nest
4.	The female Anopheles bites and sucks blood from humans

Formation of tropical forests needs mean annual temperature and mean annual precipitation as:

1. 18 – 25^oC and 150 - 400cm

2. 5 – 15^oC and 50 – 100 cm

3. 30 – 50^oC and 100 – 150cm

4. 5 – 15^oC and 100 – 200 cm

The table below gives the populations(in thousands) of ten species(A--J) in four areas (a-d) consisting of the number of habitats given within brackets against each. Study the table and answer the question as follows: 
which area out of a to d shows maximum species diversity? 

1. b

2. c

3. a

4. d

The population of an insect species shows an explosive increase in numbers during the rainy season followed by its disappearance at the end of the season. What does this show?

If the mean and the median pertaining to a certain character of a population are of the same value, the following is most likely to occur:

1. a normal distribution

2. a bi-modal distribution

3. a T-shaped curve

4. a skewed curve

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

  
1.  Stable population
2.  Declining population
3.  Expanding population
4.  Vanishing population

According to Darwin, organic evolution is due to: