NEET Genetics and Evolution

Question 1

Which of Mendel's laws states that alleles for different traits are inherited independently of each other?

Accepted Answer

Law of Independent Assortment

Answer

The Law of Independent Assortment states that genes for different traits segregate independently during gamete formation, explaining dihybrid cross outcomes.

Question 2

In a monohybrid cross between two heterozygotes (Aa × Aa), what is the expected phenotypic ratio in the offspring?

Accepted Answer

3:1

Answer

The cross Aa × Aa produces a 1:2:1 genotypic ratio (AA:Aa:aa), but since A is dominant, the phenotypic ratio is 3 dominant to 1 recessive.

Question 3

An allele that is expressed in the phenotype only when present in homozygous form is called:

Accepted Answer

Recessive

Answer

A recessive allele is only expressed in the phenotype when an individual carries two copies of it, as the dominant allele masks its expression in heterozygotes.

Question 4

A cross between a homozygous dominant (AA) and a homozygous recessive (aa) parent produces offspring that are:

Accepted Answer

All heterozygous (Aa)

Answer

When AA × aa cross, every offspring receives one A allele from the dominant parent and one a allele from the recessive parent, making all offspring heterozygous Aa.

Question 5

Which of the following is the best example of codominance in genetics?

Accepted Answer

ABO blood group type AB in humans

Answer

In blood type AB, both the A and B antigens are fully expressed simultaneously on red blood cells, demonstrating true codominance where neither allele dominates the other.

NEET - National Eligibility cum Entrance Test Practice Test

NEET - National Eligibility cum Entrance Test Practice Test

NEET Genetics and Evolution