Biology Multiple Choice Questions on “Polygenic Inheritance”.
1. What kinds of traits were described by Mendel?
a) Contrasting traits
b) Alternative forms
c) Mixed forms
d) Opposite and recessive forms
Answer: a
Clarification: Through the experiments of pea conducted by Mendel, he described distinct contrasting traits such as flower colour which are either purple or white.
2. What are polygenic traits?
a) Traits controlled by a single gene
b) Traits not controlled by any genes
c) Traits controlled by two genes
d) Traits controlled by three or more genes
Answer: d
Clarification: Traits are the feature of a character by which we can distinguish organisms. Traits which are generally controlled by three or more genes are known as polygenic traits.
3. Which of the following is a classic example of polygenic inheritance?
a) Skin colour in humans
b) Blood groups
c) Flower colour in peas
d) Stem height in peas
Answer: a
Clarification: Skin colour in humans is a classic example of polygenic inheritance as this trait is controlled by three or more genes and we can see that this trait is not so distinct amongst the human population and is spread across a gradient.
4. In humans, only tall and short people exist.
a) True
b) False
Answer: b
Clarification: Height of humans is a polygenic trait and is therefore not limited to only tall and short people. Instead of two distinct alternative traits, a range of all the possible heights is present in a human population.
5. What are polygenes?
a) Genes involved in quantitative inheritance
b) Genes involved in the qualitative inheritance
c) Genes involved in multiple allelism
d) Multiple genes for a single trait
Answer: a
Clarification: Genes which are involved in quantitative inheritance are called as polygenes. In quantitative inheritance, each dominant allele expresses itself as a part of functional polypeptide and the full trait is shown when all the dominant alleles are present in an organism.
6. Which of the following scientists demonstrated the quantitative traits in wheat?
a) Ernst Haeckel
b) H. Nilsson-Ehle
c) West
d) Paul Vincent
Answer: b
Clarification: H. Nilsson-Ehle in 1908 and East in 1910 demonstrated the segregation and assortment of genes that controlled the quantitative traits, e.g., Kernel colour in wheat and corolla length in tobacco.
7. Which two varieties of wheat were crossed by H. Nilsson to study the kernel colour in wheat?
a) Red and black kernelled variety
b) Red and white kernelled variety
c) White and black kernelled variety
d) Black and blue kernelled variety
Answer: b
Clarification: In order to study the kernel colour of wheat, H. Nilsson crossed red kernelled variety with a white kernelled variety of wheat. He found out that the kernel colour in wheat is determined by AA and BB genes.
8. What was the ratio of F2 generation when red and white kernelled variety of wheat were crossed?
a) 1: 2: 1
b) 9: 3: 3: 1
c) 1: 4: 6: 4: 1
d) 3: 1
Answer: c
Clarification: The ratio of F2 generation when red and white kernelled wheat varieties were crossed was obtained as-1: 4: 6: 4: 1. Also, five different phenotypic classes were obtained.
9. Which of the following is not a phenotypic class of the F2 generation in wheat?
a) Extreme red
b) Deep red
c) Black
d) White