The process by which new species develop from the existing species is known as speciation.
Factors leading to speciation:
(i)Geographical isolation of a population caused by various types of barriers like mountain ranges, rivers, sea etc. The geographical isolation leads to reproductive solation due to which there is no flow of genes between separated groups of population.
(ii)Genetic drift caused by drastic changes in the frequencies of particular genes by chance alone.
(iii)Variations caused in individuals due to natural selection.
(iv)Drastic change in the genes or DNA called mutation is also a cause of speciation. Reproductive isolation cannot be major factor in the speciation of a self-pollinating
plant species. This is because, it does not depend on any other plant for its reproduction process.

Evolution is the sequence of gradual changes which take place in the primitive organisms over millions of years in which new species are produced.
(a)It is through the constant process of evolution taking place in the organisms since the origin of life that such an enormous variety of plants and animals have come to exist on this earth at present.
(b)There is an inbuilt tendency to variation during reproduction due to errors in DNA copying and as a result of sexual reproduction.
(c) Fossils are the remains of impressions of dead plants or animals which died millions of
years ago. They study of fossils helps us to know about the evolution of species. Fossils tell us how new species are developed from the old. Fossils provide evidence of evolution by revealing characteristics of past organisms and the changes that have occurred these organisms to give rise to present organisms. Therefore, fossils have an importance in deciding evolutionary relationship.

(a) Mendel choose garden pea for his experiment because pea plants was self fertilising and have short life cycle.
(b) Mendel performed experiments on a garden pea (Pisumsativum) with different visible contrasting characters. He selected seven contrasting pairs of characters such as tall / short plants, purple / white flower colour etc.
(c) Mendel performed his experiment on tall and dwarf plant and interpreted his results to show that the traits may be dominant or recessive. Parent plants: True breeding tall pea plant was crossed with true breeding dwarf pea plant. Production of F₁ plants: All F₁ plants were found to be tall. Results of self-pollination ofF₁ plants or F₂plants: Mendel found that on self-pollination of F₁ plants, the progenies obtained in F₂ generations were not all tall plants. Instead, one- fourth of F₂plants were found to be dwarf.
Mendel's explanation for the reappearance of the short trait: From this experiment, Mendel concluded that the F₁ tall plants were not true breeding. They were carrying
both the traits. They appeared tall, because the tall trait was dominant over the dwarf trait.

(a) Characters are controlled by genes.
(b) Each gene controls one character.
(c) There may be two or more forms of the gene.
(d) One form may be dominant over the other.
(e) Genes are present on chromosomes.
(f) All individuals will have two forms of the gene whether similar or dissimilar.
(g) The two forms separate at the time of gamete formation and brought together in the zygote. 

The traits developed in an individual during its life time due to the effect of environmental factors are called acquired traits. These traits are also called somatic variations as they affect the structure and functioning of cells, tissues and organs without influencing the genetic material. Example - colour of seeds, colour of eyes.
A trait which is caused by a change in its gene or DNA is called an inherited trait. In other words, the traits which are passed from parents to their offspring generation after generation are called inherited traits. Example - loss of a finger in an accident.

(a) Yes.
(b) Geographical isolation prevents gene flow between populations of a species whereas asexual reproduction generally involves only one individual. Slowly the separated individuals will reproduce among themselves and generate new variations. Geographical isolation gradually leads to genetic drift. Continuous accumulation of those variations through a few generations may ultimately lead to the formation of a new species.

Since the traits inherit independently there is appearance of new combinations of characters in F₂ progeny.

RrYy (Round yellow).

(a) Round yellow
(b) Round yellow, Round green, Wrinkled yellow, Wrinkled green.
(c) Wrinkled green
(d) Round yellow.

Only those changes in the DNA or germ cells will be passed on to the progeny resulting in the variations in them. Since acquired characters do not produce any change in the DNA of germ cells, they cannot be inherited.