Heredity and Evolution MCQ 1
13. Select the correct statement
(a) Tendril of a pea plant and phylloclade of Opuntia are homologous
(b) Tendril of a pea plant and phylloclade of Opuntia are analogous
(c) Wings of birds and limbs of lizards are analogous
(d) Wings of birds and wings of bat are homologous
Ans. (a) Tendril of a pea plant and phylloclade of Opuntia are homologous
Explanation: They are modified stems but serve different functions in different plants. Hence, they are homologous structures.
14. If the fossil of an organism is found in the deeper layers of earth, then we can predict that
(a) the extinction of organism has occurred recently
(b) the extinction of organism has occurred thousands of years ago
(c) the fossil position in the layers of earth is not related to its time of extinction
(d) time of extinction cannot be determined
Ans. (b) the extinction of organism has occurred thousands of years ago
Explanation: Older fossils are found in deeper layers.
15. Which of the following statements is not true with respect to variation?
(a) All variations in a species have equal chance of survival
(b) Change in genetic composition results in variation
(c) Selection of variants by environmental factors forms the basis of evolutionary processes.
(d) Variation is minimum in asexual reproduction
Ans. (a) All variations in a species have equal chance of survival.
Explanation: Only useful variations stand a chance of survival.
16. A trait in an organism is influenced by
(a) paternal DNA only
(b) maternal DNA only
(c) both maternal and paternal DNA
(d) neither by paternal nor by maternal DNA
Ans. (c) both maternal and paternal DNA
Explanation: Since DNA in an organism is contributed by two parents, hence traits are influenced by both maternal and paternal DNA.
17. Select the group which shares maximum number of common characters
(a) two individuals of a species
(b) two species of a genus
(c) two genera of a family
(d) two genera of two families
Ans. (a) two individuals of a species
Explanation: Species is the lowest taxon and hence members of species share the maximum number of common characters.
18. According to the evolutionary theory, formation of a new species is generally due to
(a) sudden creation by nature
(b) accumulation of variations over several generations
(c) clones formed during asexual reproduction
(d) movement of individuals from one habitat to another
Ans. (b) accumulation of variations over several generations
19. From the list given below, select the character which can be acquired but not inherited
(a) colour of eye
(b) colour of skin
(c) size of body
(d) nature of hair
Ans. (c) size of body
Explanation: A person can become fat of thin because of diet. A person can develop muscular body through regular exercise. But these characters cannot be inherited in the next generation.
20. The two versions of a trait (character) which are brought in by the male and female gametes are situated on
(a) copies of the same chromosome
(b) two different chromosomes
(c) sex chromosomes
(d) any chromosome
Ans. (b) Two different chromosomes
Explanation: This is the reason; one version is expressed in some progenies, while another version is expressed in some other progenies.
21. Select the statements that describe characteristics of genes
(i) genes are specific sequence of bases in a DNA molecule
(ii) a gene does not code for proteins
(iii) in individuals of a given species, a specific gene is located on a particular chromosome
(iv) each chromosome has only one gene
(a) (i) and (ii)
(b) (i) and (iii)
(c) (i) and (iv)
(d) (ii) and (iv)
Ans. (b) (i) and (iii)
Explanation: A gene codes for proteins and hence statement (ii) is incorrect. A chromosome can have many genes and hence statement (iv) is incorrect.
22. In peas, a pure tall plant (TT) is crossed with a short plant (tt). The ratio of pure tall plants to short plants in F2 is
(a) 1: 3
(b) 3: 1
(c) 1: 1
(d) 2: 1
Ans. (c) 1:1
Explanation: A cross between (TT) and (tt) would produce progenies with following genotypes: Pure tall (TT), Mixed tall (Tt) and Short (tt). Their ratio can be given by following Punette Square:
23. The number of pair (s) of sex chromosomes in the zygote of humans is
(a) one
(b) two
(c) three
(d) four
Ans. (a) One
Explanation: 23rd pair contains sex chromosomes.
24. The theory of evolution of species by natural selection was given by
(a) Mendel
(b) Darwin
(c) Morgan
(d) Lamarck
Ans. (b) Darwin
25. Some dinosaurs had feathers although they could not fly but birds have feathers that help them to fly. In the context of evolution this means that
(a) reptiles have evolved from birds
(b) there is no evolutionary connection between reptiles and birds
(c) feathers are homologous structures in both the organisms
(d) birds have evolved from reptiles
Ans. (d) Birds have evolved from reptiles
