Question

1) When 'Aa' is crossed with 'aa' (A is dominant over a
(a) all the offspring will have dominant phenotype
(b) all the offspring will have recessive phenotype
(c) 50% of offspring will have dominant phenotype and 50% will have
recessive phenotype
(d) 75% of offsprng will have dominant phenotype and 50% will have
recessive phenotype.​

Answer 1

So, we have to cross Aa with aa where

• A is dominant allele
• a is recessive allele

Crossing using Punnett square method,

⇒ a a

A Aa Aa

a aa aa

Now, It is clear that we have

• 2 heterozygous dominant alleles
• 2 homozygous recessive alleles

So, Let us find the correct option from the above data.

[a]

All the offsprings will have dominant phenotype.

Which is absolutely wrong because only 2 of the 4 offsprings have dominant phenotype.

So, This is incorrect statement.

[b]

All the offsprings will have recessive phenotype, which is again incorrect because only 2 of the 4 offsprings have recessive phenotype.

Hence, This one is also incorrect.

[c]

The statement says that 50% of offspring will have dominant phenotype and 50% will have recessive phenotype.

Which is true because It says half of the springs will have dominant phenotype while the remaining half will have recessive phenotype. As, we have 2 dominant phenotype offsprings and 2 recessive phenotype offsprings.

[d]

This statement says that 75% will have dominant phenotype while 50% will have recessive allele.

it is on the spot, an incorrect statement. because the sum of the percentages must be equal to 100% but it adds up to 125% which is impossible hence this one is also incorrect.

So, Finally the answer is Option C.

Option C is the correct statement.

Answer 2

Answer:

So, we have to cross Aa with aa where

A is dominant allele

a is recessive allele

Crossing using Punnett square method,

⇒ a a

A Aa Aa

a aa aa

Now, It is clear that we have

2 heterozygous dominant alleles

2 homozygous recessive alleles

So, Let us find the correct option from the above data.

[a]

All the offsprings will have dominant phenotype.

Which is absolutely wrong because only 2 of the 4 offsprings have dominant phenotype.

So, This is incorrect statement.

[b]

All the offsprings will have recessive phenotype, which is again incorrect because only 2 of the 4 offsprings have recessive phenotype.

Hence, This one is also incorrect.

[c]

The statement says that 50% of offspring will have dominant phenotype and 50% will have recessive phenotype.

Which is true because It says half of the springs will have dominant phenotype while the remaining half will have recessive phenotype. As, we have 2 dominant phenotype offsprings and 2 recessive phenotype offsprings.

[d]

This statement says that 75% will have dominant phenotype while 50% will have recessive allele.

it is on the spot, an incorrect statement. because the sum of the percentages must be equal to 100% but it adds up to 125% which is impossible hence this one is also incorrect.

So, Finally the answer is Option C.

Option C is the correct statement.

Explanation:

Hope this answer will help you.✌️