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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

d) Birds have evolved from reptiles Explanation Dinosaurs were reptiles, belonging to the class Reptilia, whilst birds belong to their own... View Article

The theory of evolution of species by natural selection was given by (a) Mendel (b) Darwin (c) Morgan (d) Lamarck

b) Darwin Explanation According to Charles Darwin, evolution is a very slow and gradual process. He concluded that evolution took... View Article

The number of pair (s) of sex chromosomes in the zygote of humans is (a) one (b) two (c) three (d) four

a) One Explanation Chromosomes are a thread-like structure holding genetic information. It is present in the cell nuclei. A normal... View Article

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

c) 1:1 Explanation The parents are homozygous tall (TT) and dwarf (tt), the progeny of the F1 generation will be hybrids... View Article

Select the statements that describe characteristics of genes (i) genes are a 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)

b) (i) and (iii) Explanation Genes control the functions of DNA and RNA. Proteins are the most important materials in the... View Article

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

a) Copies of the same chromosome Explanation Copies of same chromosome from the male and female gametes pair up to form... View Article

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

c) Size of the body Explanation The size of the body is an acquired trait because it can be changed... View Article

According to the evolutionary theory, the 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

b) Accumulation of variations over several generations Explanation Darwin’s evolutionary theory of natural selection gave a more rational explanation of the... View Article

Select the group which shares the 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

a) Two individuals of a species Explanation Species is the lowest taxon hence members of the same species share a maximum... View Article

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

c) Both maternal and paternal DNA Explanation A trait of an organism is influenced by both maternal and paternal DNA.... View Article

Which of the following statements is not true with respect to variation? (a) All variations in a species have an 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

a) All variations in a species have an equal chance of survival. Explanation All variations in a species do not... View Article

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

b) The extinction of organisms has occurred a thousand years ago Explanation Fossils provide direct evidence of evolution. Fossils are body... View Article

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

(a) Tendril of a pea plant and phylloclade of Opuntia are homologous Explanation Tendril of a pea plant and phylloclade... View Article

A basket of vegetables contains carrot, potato, radish and tomato. Which of them represent the correct homologous structures? (a) Carrot and potato (b) Carrot and tomato (c) Radish and carrot (d) Radish and potato

c) Radish and carrot Explanation Homologous structures are those that are related to common ancestry. Such structures have a common... View Article

Two pea plants one with round green seeds (RRyy) and another with wrinkled yellow (rrYY) seeds produce F1 progeny that have round, yellow (RrYy) seeds. When F1 plants are selfed, the F2 progeny will have a new combination of characters. Choose the new combination from the following (i) Round, yellow (ii) Round, green (iii) Wrinkled, yellow (iv) Wrinkled, green (a) (i) and (ii) (b) (i) and (iv) (c) (ii) and (iii) (d) (i) and (iii)

(b) (i) and (iv) Explanation The new combination in F2 progeny will be round, yellow and wrinkled green. The phenotypic... View Article

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 (a) (i) and (ii) (b) (i) and (iii) (c) (ii), (iii) and (iv) (d) (i), (ii) and (iii)

(a) (i) and (ii) Explanation Evolution will not take place without change and variation the genetic material. Hence, change in... View Article

Select the incorrect statement (a) Frequency of certain genes in a population change over several generations resulting in evolution (b) Reduction in weight of the organism due to starvation is genetically controlled (c) Low weight parents can have heavyweight progeny (d) Traits which are not inherited over generations do not cause evolution

(b) Reduction in weight of the organism due to starvation is genetically controlled Explanation The factors affecting change in genetic... View Article

A zygote which has an X-chromosome inherited from the father will develop into a (a) boy (b) girl (c) X- chromosome does not determine the sex of a child (d) either boy or girl

b) Girl Explanation Sex determination seen in humans is XY sex determination. Ovum carries X chromosome, whereas sperm can carry... View Article

The maleness of a child is determined by (a) the X chromosome in the zygote (b) the Y chromosome in zygote (c) the cytoplasm of germ cell which determines the sex (d) sex is determined by chance

b) The Y chromosome in zygote Explanation A male has sex chromosomes X and Y, while a female has XX as... View Article

In human males, all the chromosomes are paired perfectly except one. This/these unpaired chromosome is/are (i) large chromosome (ii) small chromosome (iii) Y-chromosome (iv) X-chromosome (a) (i) and (ii) (b) (iii) only (c) (iii) and (iv) (d) (ii) and (iv)

c) (iii) and (iv) Explanation Y-chromosome and X-chromosome In human males, one pair called as the sex chromosomes are unpaired.... View Article

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