Question

Heterozygous tall (Tt) is crossed with homozygous tall (tt). Percentage of heterozygous tall in the progeny would be
A. 25%
B. 50%
C. 75%
D. 100 %

Answer 1

Heterozygous is a condition when there are two different traits of a particular gene. When a dominant character has to be expressed both the letters are capital. When a recessive character has to be expressed both the letters are lowercase.

Complete answer:
Heterozygous is a condition when there are two different traits of a particular gene.
Homozygous is a condition when there are identical traits of a particular gene. It is donated by two letters.
When a dominant character has to be expressed both the letters are capital.
When a recessive character has to be expressed both the letters are lowercase.
Heterozygous tall (Tt) is crossed with homozygous tall (tt) to determine the dominant and recessive trait.

| t| t
---|---|---
T| Tt| Tt
t| tt| tt

T ( normal height) — dominant trait
t ( dwarf) — recessive trait

Genotypic frequencies
Tt — heterozygous (50%)
tt — homozygous (50%)

So, the answer is B i.e 50%

Note: For example,
The dominant trait of eye color is brown. It is represented by BB.
All the remaining eye colours i.e blue, grey, green and hazel are recessive. It is represented by bb.
A homozygous person with brown eyes has BB gene i.e a dominant trait.
A homozygous person with blue eyes has bb genes i.e. a recessive trait.