# AP BIOLOGY

## HEREDITY

### MONOHYBRID CROSS

 Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
T=tall, t=short. Cross a heterozygous and a homozygous recessive. What are the chances of an offspring being tall?
 A 1 out of 4 or 25% B 2 out of 4 or 50% C 3 out of 4 or 75% D 4 out of 4 or 100%
Explanation:

Detailed explanation-1: -So, the correct option is ‘50%’.

Detailed explanation-2: -In a cross between heterozygous tall plants (Tt) and a homozygous dwarf plant (tt), the ratio in the offspring shall be 1 tall : 1 dwarf. This is because the heterozygous plant will make two types of gametes, one type having T allele and the other having t allele. Hence, the correct answer is ‘1 tall : 1 dwarf’

Detailed explanation-3: -As shown in the figure a cross between two heterozygous tall plants results in 25% homozygous tall, 50% heterozygous tall and 25% dwarf plants.

Detailed explanation-4: -Answer and Explanation: Since a Tt heterozygous, tall plant produce with equal probabilities the gametes T and t, and the tt homozygous, short plant only t gametes, when they are crossed (Tt x tt) the progeny will be 50% tall (all genotypically Tt) and 50% short (all genotypically tt).

Detailed explanation-5: -Cross between two heterozygous tall pea plants can be shown as follows : Hence, the probability of production of dwarf offsprings is 25% and tall offsprings is 75%.

There is 1 question to complete.