Question

Chapter- Genetics ( Inheritance & variation)

Solve this question with proper explanation and also u can share if there is any short trick to solve it .

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Answer 1

Answer:

ans will be option 2..

Explanation:

since the probability of being tall is 0.5 means 1/2or the half of the f1 progeny is tall and the other half is short ...so the cross will be between Tt×tt

in the second case for color of kernels is 0.75 or 3/4 of the f1 progeny .

so this will be the cross between Cc×Cc for the f1 progeny to have 0.75 percent of coloured kernels .

so now we got both the genotype for tall and coloured progeny now the parental type or the genotype of both the parents will be

TtCc×ttCc

Answer 2

Given:

For tallness:

Tall- T ( dominant)

Dwarf- t ( recessive)

For kernel color:

Color- C ( dominant)

White- c ( recessive)

In a particular dihybrid cross among the corn plant, the probability of the plant being tall is 0.5 and the probability of the kernel being colored is 0.75.

Explanation:

In order to solve this question, you must know about Mendel's three laws of inheritance.

1. Law of dominance

The offspring will always inherit the dominant trait from the parent. Inheritance of the recessive trait only happens if both the alleles are recessive.

2. Law of segregation

During segregation, only one allele of a particular character/gene enters a gamete. The offspring receives one allele for each gene.

3. Law of independent assortment

In a dihybrid cross, the inheritance/ separation of one pair of traits is completely independent of the other.

The given cross is a dihybrid cross, so we will use the third law in order to solve this question.

Now as per the law of inheritance, the inheritance for the trait of tallness will be completely independent of that of the kernel color so we can look into both the traits separately in order to find the desired parental cross.

Option 1) TtCc x TtCc

Now let's separate both the traits from each other

Tallness: Tt x Tt

Probable outcomes: TT, Tt, Tt, tt [ 3/4 th of the offsprings are tall ( i.e. 75%), 1/4 th are dwarf ( i.e. 25%) ]  

Kernel color: Cc x Cc

Probable outcomes: CC, Cc, Cc, cc [ 3/4 th of the offsprings are tall ( i.e. 75%) , 1/4 th are dwarf ( i.e. 25%) ]

The probability of the plant being tall is 0.75 and the probability of the kernel being colored is also 0.75. This can't be the answer as the condition for tallness isn't fulfilled.

Option 2) TtCc x ttCc

Now let's separate both the traits from each other

Tallness: Tt x tt

Probable outcomes: Tt, tt, Tt, tt [1/2 of the offsprings are tall ( i.e. 50%), 1/2 are dwarf ( i.e. 50%) ]

Kernel color: Cc x Cc

Probable outcomes: CC, Cc, Cc, cc [3/4 th of the offsprings are tall ( i.e. 75%) , 1/4 th are dwarf ( i.e. 25%) ]

The probability of the plant being tall is 0.5 and the probability of the kernel being colored is 0.75. Both the conditions are fulfilled so the answer is option 2.

I won't be solving further as I got the required answer but the remaining two options can be solved similarly.