Inheritance And Variations

Question 1

In Monohybrid cross
Phenotypic ratio :
Genotypic ratio :

Answer 1

In Monohybrid cross
Phenotypic ratio : 3:1
Genotypic ratio : 1:2:1

Question 2

In Monohybrid cross , formula for:
No of gametes=
No. Phenotypes=
No. Of genotypes=
No of zygotes =

Answer 2

No of gametes= 2^n
No. Phenotypes= 2^n
No. Of genotypes= 3^n
No of zygotes = (gamete)²

Question 3

How to produce a true breeding line?

Answer 3

True breeding lines are produced by doing continuous selfing of HOMOZYGOUS PARENTS for many generations.

Question 4

On the basis of monohybrid cross Mendel gave which two laws

Answer 4

Law of dominance
Law of segregation (purity of gametes)

Question 5

Ncert line

The law of dominance is used to explain…

Answer 5

The law of dominance is used to explain the expression of only one of the parental characters in Monohybrid cross in ** F₁** and the expression of both in the F₂.

It also explains the proportion of 3:1

Question 7

What are the exceptions for law of dominance

Answer 7

1. Incomplete dominance
2. Co-dominance
3. Pleiotropy

Question 8

In incomplete dominance the ratio of phenotype and genotype is , and also tell its the examples

Answer 8

Examples —
1. Mirabilis jalapa/ 4O clock plant
2. Antirrhinum majus/ snapdragon/ Dog flower

Phenotype :

Red : Pink : white = 1 : 2 : 1

Genotype

RR : Rr : rr = 1 : 2 : 1

Question 9

In test Cross Mendel did the crossing b/w?

What are the phenotypic and genotypic ratio obtained from
TT and Tt

Answer 9

F2 Tall × Recessive Parent ( dwarf)

TT × tt ,
All tall plants obtained, so the ratio
For Genotype = 1 (Tt)
Phenotype = 1 (all tall)

Tt × tt
50% tall and 50% dwarf obtained

Genotype = Tt : tt = 1:1
Phenotype = Tall : dwarf = 1:1

Question 10

Whats multiple allele, give examples

Answer 10

Usually one Gene has two alleles and it controls one character

But when one Gene has more than two alleles and controls one character

Examples:
1. AB BLOOD GROUP
2. SICKLE CELL ANAEMIA
3. COAT COLOR IN CATTLE