Since dwarfness (recessive trait) has appeared in the progeny, the tall pea plant must be heterozygous for tallness, i.e. its genotype is Tt

The phenotypic ratio is 3 Tall : 1 dwarf.
Since tallness is dominant over dwarfness, the homozygotes (TT) as well as the heterozygotes (Tt) are tall.
The recessive trait is expressed only under homozygous condition (tt) and hence appears only in one-fourth of the progeny.

Inheritance of flower colour in Antirrhinum majus:

This character shows incomplete dominance , where neither of the two alleles of the gene is completely dominant and the Fl hybrid is intermediate between the two.

Phenotypic ratio : 3 Tall : 1 Dwarf Genotypic ratio : 1 TT : 2 Tt : 1 tt
Two-thirds of the tall progeny is heterozygous.
It is because the gene for tallness (T) is dominant and expresses itself in the heterozygous condition, Tt.

It is due to the phenomenon of linkage. fruit fly produces all ova with one
Linkage is defined as the phenomenon X-chromosome and the male fowl in which two or more linked genes are produces all the sperms with one inherited together and their frequency Z-chrornosorne, along with autosomes.
of recombination in a test cross 2.13 Parents Father x Mother progeny is less than the expected 50 AB group 0 group percent.     
In this case, the genes for eye colour  Gametes and body colour show linkage and do not always allow for crossing over Progeny during gamete formation; hence the  parental combination is in greater - The gene for blood group exists in proportion than that of recombinants.
\({ F }_{ 1 }\) generation Aali-(Axial flowers, inflated flowers)
The phenotype of the  \({ F }_{ 1 }\)progeny-Axial flowers and inflated pods
The genotype of the   \({ F }_{ 1 }\)progeny-Aali

Alleles are polymorphs that differ in their nucleotide sequence resulting in contrasting phenotypic expression. These are the alternative forms of a same gene, e.g. genes for height have two alleles, one for dwarfness (t) and one for tallness (T). Significance of alleles are
(i) A characler may have two or more contrasting phenotypic expression, thus resulting in variation in a population.
(i) These are used in the studies of inheritance.

- Mendelian phenotupic ratio of a monohybrid cross is 3 : 1 and the genotypic ration is 1 : 2 : 1.

- It can be mathematically condensed as (ax + by)².

(i) A white colour dog will be chosen.
(ii) White colour is recessive; a homozygous white do, that breeds true will be chosen.
(iii) Such a cross is called test cross.

1.It leads to an increase in a whole set of chromosomes of the organism.
2.  It is called polyploidy.

Three genes are responsible for expression of ABO blood groups.For skin colour in man three pairs of genes are responsible.

According to their phenotypic effects following kinds of mutations may occur:
(a) Dominant mutations, i.e., expressed phenotypically all the times;
(b) Recessive mutations, usually not expressed except homozygous recessive state;
(c) Lethal mutations, result in the death of the organisms.

Real father can be identified by blood group analysis and with DNA fingerprinting. Value:- critical thinking ,trust making