In the $F_2$ generation of Mendel's dihybrid cross,which phenotype is observed with the highest frequency?

In Mendel's dihybrid cross,how many seeds out of the $F_2$ generation ratio of $9:3:3:1$ were found to be round?

Which genotype characterises an organism that is heterozygous for two genes?

If the genotype of an organism for two pairs of genes is represented by $AaBb$,then the possible genetic combinations of gametes after meiosis will be:

In peas,tallness is dominant over dwarfness and red colour of flowers is dominant over the white colour. When a tall plant bearing red flowers was pollinated with a dwarf plant bearing white flowers,the different phenotypic groups were obtained in the progeny in numbers mentioned against them:
Tall,Red $= 138$
Tall,White $= 132$
Dwarf,Red $= 136$
Dwarf,White $= 128$
Mention the genotypes of the two parents and of the four offspring types.

The genotypes of a plant variety were $TtHh, Tthh, ttHh$ and $tthh$,where $T =$ tallness and $H =$ hairy stem. Which one of the following crosses would produce progeny giving a phenotypic ratio approximately $1 : 1 : 1 : 1$?