What is the genotype and phenotype for a zygous dominant plant that is crossed with a dwarf plant?

The plant is zygous dominant so this means both its genes contain the dominant trait and its phenotype will be dominant or normal sized. If you cross it with a dwarf plant then all the offspring will be heterozygous but will display the dominant trait. So the zygous dominant plant pes on a dominant gene and the zygous recessive plant pes on a recessive gene, but it's the dominant gene that's expressed. Say you crossed two of the offspring, they each have one dominant and one recessive gene (say Aa) then their offspring will be 25% AA, 25% aa and 50% Aa so their phenotype will be 25% dwarf and 75% normal. Hope that helps xx