Fill in the punnett square for a cross between the following individuals.

aa x aa – dominant trait is red, recessive trait is white

50% of the offspring will have the "Aa" alleles and for this reason they will have the dominant, red characteristic.

50% of the offspring will have the "aa" alleles and for this reason, they will have a white, recessive characteristic.

Explanation:

The punnet square shown in the question above is filled in the figure attached below. In it, we can see that the cross between a living being with the "Aa" alleles and a living being with the "aa" alleles would result in 50% "Aa" and 50% "aa" offspring. Those who have the dominant allele "A" will have a dominant characteristic of red color, while those who do not have the dominant allele, will have a recessive characteristic of white.

"do a testcross with a homozygous recessive plant."

you didn't give any options but heres what i can tell you: an inference is likely to change based on additional observations. the latter is something that you have seen or sensed using your sensory organs while the former is like a conclusion out from what you have observed.