In sexual reproduction, two individuals having different variations combine their DNA to give rise to a new individual. Therefore, sexual reproduction allows more variations, whereas in asexual reproduction, very less chance of variations can only occur when the copying of DNA is not accurate. However, if there are more variations, then the resultant DNA will not be able to survive inside the inherited cellular apparatus. Thus, the resultant DNA will be able to survive making the variations viable. Variants help the species to survive in all the conditions. Environmental conditions such as heat, light, pests, and food availability can change suddenly at only one place. At that time, only those variants resistant to these conditions would be able to survive. This will slowly lead to the evolution of a better adapted species. Thus, variation helps in the evolution of sexually reproducing organisms.

Inherited traits are the characteristics transmitted from parents to their offspring. Acquired traits are characteristics which are developed during the lifetime of an individual. Acquired traits are not passed on to the next generation. For example, if we breed a group of mice, all their progeny will have tails. Now, if the tails of these mice are removed by surgery and allowed to breed, the next generation mice will also have tails. If these tails are also removed and allowed to breed, the progeny of mice will again have tails. Removal of tail by surgery is an acquired trait and do not change the genes of germ cells and hence, are not passed on to the next generation.

Equal genetic contribution of male and female parents in the progeny is ensured by the equal inheritance of chromosome from each parent.
Human possesses 23 pairs of chromosomes, of which 22 pairs are autosomes and 1 pair is the sex chromosomnes.
The two sex chromosomes in human are X and Y. Females have 2X chromosomes and males have a X and Y chromosome.
During the process of fertilization, a haploid sperm fuses with a haploid ovum to produce a diploid zygote. Zygote receives equal amount of genetic material from each parent and thus, retains the diploid narure on fertilizarion.

The presence of feathers in dinosaurs and birds indicates that they are evolutionarily related. Dinosaurs had feathers not for flying but instead these feathers provided
insulation to these warm-blooded animals. However, the feathers in birds are used for flight. This proves that reptiles and birds are closely related and that the evolution of
wings started in reptiles.

Those organs which have the same basic structure but different functions are called homologous organs.
The wings of a butterfly and the wings of a bat cannot be regarded a homologous because they have different basic design though they are used for the same purpose of flying. 

Variant genotypes can be produced by
(a) Mutation in genes and chromosomes.
(b) Recombination of genes.
(c) Hybridization of genes.

The woman has ova having X chromosome. The male has sperm with X as well as Y chromosomes. In this case, the 'X' chromosome of male gamete fuses with the ova of 'X' chromosome.

(a) It had a short life cycle.
(b) Cross pollination can be achieved easily.
(c) Flowers can be self - pollinated.
(d) There are male and female flowers present in same plant (bisexual).
(e) Easy hybridization.
(f) It possess seven contrasting characters.
(g) It could be easily raised, maintained and handled.

(a) No
(b) Though animals have a vast diversity in structures they, do not have a common ancestry. This is because common ancestry may limit the extent of diversity. As many of these diverse animals inhabit the same habitat, their evolution by geographical isolation and speciation is also not likely.

(a) The structures which have a common basic structure but perform different functions are called homologous structures. Example-fore limbs of reptiles, amphibians and mammals.
(b) Yes.

Black hair

Female baby

(a) Either the seeds bought by her were of pure tall plants (TT) or a hybrid having gene for both tallness and dwarfness (Tt).
(b) If the seeds bought by her had been of pure tall and dwarf type, she would have got both tall and dwarf plants:
(c) In case the seeds are of hybrid tall (Tt) type then 75% of plants will be tall and 25% will be of dwarf type.

(a) No, she should not take the medicine.
(b) Of course she should visit a doctor to get information.
(c) She is having 50% chances of having a male child as 50% sperms carry Y chromosome and 50% X chromosome.