If several pea plants with the genotype ttyy are crossed with pea plants with the genotype ttyy what percentage of the offspring will be expected to have the ttyy allele combination

25%

Explanation:

A cross between two heterozygous plant can will result in the following pair.

To get this combination we need to cross the first pair individually and then the second pair individually.

    T         T                        Y         y

T   TT     TT                   y   Yy     yy

t    Tt       Tt                   y   Yy      yy

The ratio of TT= 1/2        The ratio of Yy= 1/2

The total ratio of TTYy= 1/2* 1/2 = 1/4 which is 25% of the total offspring produced by the cross between the pair TTYy and  Ttyy.

The offspring produced is heterozygous.

sheep is a herbivore animal whereas grasshopper belongs to the class chordates but both of them feed on greens.  

if grasshopper and sheep feeding on a pasture land, i do not think both of them will have any impact on each other. however, the number of the species can make difference. since sheep feed on greens, there is a possibility there left no pasture land for the grasshoppers or they may get extinct.