What are homologous structures? Give an example. Is it necessary that homologous structures always have a common ancestor?

A basket of vegetables contains carrot, potato, radish and tomato. Which of them represent the correct homologous structures?

All the human races like Africans, Asians, Europeans, Americans and others might have evolved from a common ancestor. Provide a few evidences in support of this view.

Give the pair of contrasting traits of the following characters in pea plant and mention which is dominant and recessive (i) yellow seed

Study the following cross and showing self pollination in $F_1$, fill in the blank and answer the question that follows.

 

Two pea plants one with round green seeds ($RRyy$) and another with wrinkled yellow ($rrYY$) seeds produce $F_1$ progeny that have round, yellow ($RrYy$) seeds. When $F_1$ plants are selfed, the $F_2$ progeny will have new combination of characters. Choose the new combination from the following
(i) Round, yellow
(ii) Round, green
(iii) Wrinkled, yellow
(iv) Wrinkled, green

New species may be formed if
(i) DNA undergoes significant changes in germ cells
(ii) chromosome number changes in the gamete
(iii) there is no change in the genetic material
(iv) mating does not take place

Does geographical isolation of individuals of a species lead to formation of a new species? Provide a suitable explanation.

The two versions of a trait (character) which are brought in by the male and female gametes are situated on

Give the pair of contrasting traits of the following characters in pea plant and mention which is dominant and recessive (ii) round seed

From the list given below, select the character which can be acquired but not inherited

Exchange of genetic material takes place in

Why did Mendel choose pea plant for his experiments?

In the following crosses write the characteristics of the progeny

According to the evolutionary theory, formation of a new species is generally due to

A trait in an organism is influenced by

The number of pair (s) of sex chromosomes in the zygote of humans is

Give reasons why acquired characters are not inherited.

Give reasons for the appearance of new combinations of characters in the $F_2$ progeny.

Which of the following statements is not true with respect to variation?