Most often the factor that initiates the speciation of two populations is:

1.	Geographic isolation
2.	Inability of the gametes to fuse
3.	Different courtship behaviours
4.	Different copulatory organs

The oldest fossils resemble:

1. Amoeba

2. Red algae

3. Heterotrophic bacteria

4. Autotrophic bacteria

Reptilian ancestors of the mammals were the :-
1. Therapsids
2. Thecodonts
3. Pterosaurs
4. Plesiosaurs
 

Given below is the representative evolutionary history of vertebrates through geological periods. A, B, C, and D respectively are:

Karn & Penrose showed that birth weight follows a normal distribution, that mortality for newborns is greater for those either under-or over-weight, and that the mean birth weight (7 lbs) coincides with that showing minimum mortality. The type of natural selection operating here is shown by the graph :

1. (a)

2. (b)

3. (c)

4. Both (a) and (b)

The following two plants exhibit :

1. Analogous organs

2. Vestigial organs

3. Rudimentary organs

4. Homologous organs

In the apparatus of Urey and Miller experiment, the gases [G] contained in the flask are :

1. Methane, Carbon dioxide, Ammonia and Water vapour
2. Methane, Hydrogen cyanide, Ammonia and Water vapour
3. Methane, Ammonia, Hydrogen and Water vapour
4. Carbon dioxide, Oxygen, hydrogen and ammonia 

Lamarck's theory of evolution is also called

1. Theory of special creation

2. Inheritance of acquired characters

3. Survival of the fittest

4. None of these

Industrial melanism is an example of

(1) Neo Darwinism

(2) Natural selection

(3) Mutation

(4) Neo Lamarckism

Which is the most common mechanism of genetic variation in the population of a sexually reproducing organism?

(1) Transduction

(2) Chromosomal aberrations

(3) Genetic drift

(4) Recombination