How many different kinds of gametes may be produced by an organism with the genotype $RrYy$?

Which of the following is heterozygous for two pairs of alleles?

In the $F_2$ generation of a dihybrid cross of homozygous parents,the number of genotypes and phenotypes will be respectively . . . . . . .

In Mendel's dihybrid cross,what is the proportion of the dominant homozygous plants in the $F_2$ generation (in $/16$)?

In a dihybrid cross,when $F_1$ plants $(RrYy)$ are self-hybridized,what is the segregation ratio of yellow and green seeds in the $F_2$ generation?

From a mating of two dihybrid individuals $(AaBb \times AaBb)$,how many of the $16$ possible zygote combinations would be expected to be homozygous dominant for both genes?