ABO blood group system is due to
- multifactor inheritance
- incomplete dominance
- multiple allelism
epistasis
The Correct Option is C
Solution and Explanation
Some genes can have more than two alleles. When a trait is controlled by more than two alleles, it is called multiple allelism. In humans, the blood group is determined by three alleles (IA, IB and IO) of a gene I. A person can only have two of the three alleles, determining his blood group. Person with both IA alleles belongs to A blood group, IAIB to AB blood group and B group for both IB alleles. Similarly, persons with O blood group have both alleles Io.
The other three options are incorrect as they do not account for the blood group in humans.
- Multifactor Inheritance - It refers to the trait or disease caused by more than one factor like birth defect, chronic illness etc.
- Incomplete Dominance - The condition in which the two alleles of a gene are partially expressed resulting in a different phenotype not seen in parents, is called incomplete dominance.
- Epistasis - It is a condition in which the expression of a gene is inhibited due to the presence of another gene.
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Concepts Used:
Principles of Inheritance and Variation - Mutation
A Mutation is a change in the sequence of our DNA base pairs caused by numerous environmental stimuli such as UV light or mistakes during DNA replication. Germline mutations take place in the eggs and sperm and can be passed onto offspring, whereas somatic mutations take place in body cells and are not passed on.
Types of Mutations
There are three types of mutations, which are as follows:
Silent mutation
It refers to any change in DNA sequence that has no effect on the amino acid sequence in a protein or the functions that a protein performs. There is no phenotypic indication that a mutation has occurred.
Nonsense mutation
When there is a change in the sequence of base pairs due to a point mutation, that results in a stop codon. This leads to a protein that is either shortened or non-functional.
Missense mutation
A missense mutation occurs when a point mutation causes a change in the codon, which then codes for another amino acid.
The mutation is caused by the following factors:
Internal Causes
When DNA copies incorrectly, the majority of mutations occur. Evolution occurs as a result of all of these mutations. DNA makes a copy of itself during cell division. When a copy of DNA isn't flawless, it's called a mutation since it differs somewhat from the original DNA.
External Causes
When certain chemicals or radiations are used to break down DNA, it causes the DNA to break down. The thymine dimers are broken by UV radiation, resulting in altered DNA.