CBSE Questions for Class 10 Biology Heredity And Evolution Quiz 5 - MCQExams.com

• Species are those which are capable of interbreeding among themselves and can exchange genes. These are closely related. 
• The offspring produced as a result of interbreeding will be fertile in nature.
• Gene flow occurs between the populations of a species. 
• For example, gene flow can occur within plant species, when pollen is carried by bees or blown by the wind from one population of flowering plants to another of the same species. 
• Members of the two different species cannot interbreed and produce fertile offspring. Thus, each species is reproductively isolated from every other species.
  
• Genetic variation is the presence of differences in sequences of genes between individual organisms of a species.
  

Solution

Correct answer is option A.

Explanation for correct option:

Gregor Mendel – now known as father of genetics is the person who introduced the idea of genes and inheritance.

He studied 7 traits in pea plants which were as follows.

i.          Plant height (tall/ dwarf)

ii.         Flower colour (purple/white)

iii.       Flower position (terminal /axial)

iv.        Seed colour (yellow/green)

v.         Seed shape (round/ wrinkled)

vi.        Pod colour (green/yellow)

vii.       Pod shape (inflated/ constricted)

• Mendel studied the common garden pea plant that exhibited discontinuous characteristics such as flower colour and pea texture. 
• Mendel chose seven pairs of contrasting traits, namely plant height, flower position, pod colour, pod shape, seed colour, seed shape and flower colour. He observed only two alternative forms of a trait, for example, tall and dwarf in plant height, the axial and terminal position of flowers etc.
•  Although his predecessors studied the inheritance pattern of distinct traits; but he was first to apply the quantitative approach, the statistical analysis, to biological science which allowed him to interpret and analyse the pattern of inheritance mathematically.
• This helped Mendel to explain the laws of heredity. 
• Thus, the correct answer is option C.

• If an organism has two copies of the same allele, for example, AA or aa, it is homozygous for that trait. 
• If the organism has one copy of two different alleles, for example, Aa, it is heterozygous.
• The dominant character is expressed in both homozygous and heterozygous condition while the recessive express only in the homozygous condition.
• So, the correct answer is option A.

• The offspring from a cross between first parent individuals are referred to as first filial generation; $$F_1$$ generation. Plants of $$F_1$$ generation were allowed to self pollinate to obtain $$F_2$$ generation. 
• Cross-pollination is the transfer of pollens from one plant to the stigma of the flower borne on the different plants of the same species.
• The genetic constitution of a cell or organism refers to its genotype. 

Correct Option: C

Explanation:

• An organism is a hybrid of its maternal and paternal traits and is called a recombinant.
• Therefore, both maternal and paternal traits are equally responsible for the traits of an organism.

Hence, a trait of organism is influenced by both paternal and maternal.