In such a population natural selection and random mating does not occur. This is because both these process promotes evolution which disrupts the Hardy-Weinberg equilibrium.

(i) Ontogeny is embryonic development, i.e. the origin and development of an organism from an embryo to an adult.
(ii) Phylogeny is ancestral history, i.e. the evolutionary development and history of a species or higher taxonomic grouping of organisms.

(p + q)2 =p2+2pq+q2=1

1. Germplasm - Protoplasm contained inside the germ cells that is transmitted from one generation to other is called germplasm.
2. Branching descent-It the formation of different types of species from a common ancestor due to variations and adaptations to varying ecological niches.

( a ) Dark and grey coloured moths on the bark of a tree in an unpolluted area
(b) Dark and grey coloured moths on the bark of a tree in a polluted area.
Above picture shows industrial melanism. Prior to industrial revolution England had plenty of lichen flora on the bark of trees giving light coloured background suitable for white coloured moth but dark coloured moths were easily predated by the predators declining their numbers. After industrial revolution lichens disappeared from the tree barks which caused easy predation of white coloured moths than dark coloured declining the numbers of white moth in course of time.

(i) Homologous structure are :
(a) Forelimbs of whales and bats; and
(b) Thorns of Bougainville and tendrills of Cucurbita.
(ii) They exhibits divergent evolution.

(i) Large head, mobile neck, short trunk with broad chest, long limbs;
(ii) large, highly convoluted brain;
(iii) well developed facial muscles to express emotions; and
(iv) lack of tail.

1. The biodiversity we see today is the story of evolution, i.e. evolution is considered as a process, that has resulted in various life forms.
2. If we talk about the life on earth, evolution is considered as a consequence of the process, called natural selection.
3. It is difficult to decide, whether evolution and natural selection are processes or results of some unknown processes.

1. Evolution is not a direct process in terms of determinism
2. As the environment changes, due to meteorological, biological and other physical activities, the organisms which are better adapted to the changed environment are selected by nature in a much lesser time scale.
3. It is also true for natural selection and evolution of antibiotic-resistant strains of bacteria in a time scale of months.
4. So, evolution is a stochastic process based on chance events in nature and chance mutation in the organism.

1. convergent evolution is the evolutionary process, where anatomically different structures in different groups of organisms evolve towards the same function, in similar habitats.
2. Such structures in different groups of organisms which perform similar function, but are anatomically different, are called analogous organs.
3. The wings of a butterfly and those of bird are anatomically different, but perform the same function (flying); hence they are said to be analogous organs.