Class 10 Biology



Heredity & Evolution

Exemplar Problems MCQ II

Select the correct statement

  • Tendril of a pea plant and phylloclade of Opuntia are homologous
  • Tendril of a pea plant and phylloclade of Opuntia are analogous
  • Wings of birds and limbs of lizards are analogous
  • Wings of birds and wings of bat are homologous

    Answer: (a) Tendril of a pea plant and phylloclade of Opuntia are homologous

Explanation: They are modified stems but serve different functions in different plants. We know that organs with similar origin/design are called homologous structures.

If the fossil of an organism is found in the deeper layers of earth, then we can predict that

  • the extinction of organism has occurred recently
  • the extinction of organism has occurred thousands of years ago
  • the fossil position in the layers of earth is not related to its time of extinction
  • time of extinction cannot be determined

    Answer: (b) the extinction of organism has occurred thousands of years ago

Explanation: Newer fossils are deposited in layers above older fossils.


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

  • All variations in a species have equal chance of survival
  • Change in genetic composition results in variation
  • Selection of variants by environmental factors forms the basis of evolutionary processes.
  • Variation is minimum in asexual reproduction

    Answer: (a) All variations in a species have equal chance of survival

Explanation: Useful variations stand a chance of survival because nature selects only the useful variations.

A trait in an organism is influenced by

  • paternal DNA only
  • maternal DNA only
  • both maternal and paternal DNA
  • neither by paternal nor by maternal DNA

    Answer: (c) both maternal and paternal DNA

Explanation: Both parents equally contribute to the DNA of an individual.

Select the group which shares maximum number of common characters

  • two individuals of a species
  • two species of a genus
  • two genera of a family
  • two genera of two families

    Answer: (a) two individuals of a species

Explanation: The lowest taxon shows the maximum number of common characters. Species is the lowest taxon.

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

  • sudden creation by nature
  • accumulation of variations over several generations
  • clones formed during asexual reproduction
  • movement of individuals from one habitat to another

    Answer: (b) accumulation of variations over several generations

Explanation: Theory of sudden creation has long been disproved by scientists. It is the accumulation of variations over successive generations which results in origin of a new species.


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

  • colour of eye
  • colour of skin
  • size of body
  • nature of hair

    Answer: (c) size of body

Explanation: Traits in other options are always inheritable traits.

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

  • copies of the same chromosome
  • two different chromosomes
  • sex chromosomes
  • any chromosome

    Answer: (b) Two different chromosomes

Explanation: This obeys Mendel’s First Law of Inheritance.

Select the statements that describe characteristics of genes

  • genes are specific sequence of bases in a DNA molecule
  • a gene does not code for proteins
  • in individuals of a given species, a specific gene is located on a particular chromosome
  • each chromosome has only one gene
    • (i) and (ii)
    • (i) and (iii)
    • (i) and (iv)
    • (ii) and (iv)

      Answer: (b) (i) and (iii)

Explanation: A gene codes for a protein, and a chromosome can have many genes. So, statements (ii) and (iv) are incorrect.

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

  • 1 : 3
  • 3 : 1
  • 1 : 1
  • 2 : 1

    Answer: (c) 1 : 1

Explanation: Following combinations of genotype emerge in F2 generation: TT (1), tt(1) and Tt (2). This shows that ratio of pure tall (TT) to pure short (tt) is 1:1.


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

  • One
  • Two
  • Three
  • Four

    Answer: (a) One

Explanation: The sex chromosomes are in the 23rd pair.

The theory of evolution of species by natural selection was given by

  • Mendel
  • Darwin
  • Morgan
  • Lamarck

    Answer: (b) Darwin

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

  • reptiles have evolved from birds
  • there is no evolutionary connection between reptiles and birds
  • feathers are homologous structures in both the organisms
  • birds have evolved from reptiles

    Answer: (d) Birds have evolved from reptiles



MCQ I

Short Answer

Long Answer I

Long Answer II

Lesson