Question

how are punnett squares used?
they identify how crossing over affects genetic variation.
they help predict possible genotypes that result from a cross.
they indicate the total number of offspring that will result from a cross.

Explanation:

Punnett squares are grids used in genetics. They take the alleles of parents and combine them systematically. By doing this, they show all possible combinations of alleles in offspring. This helps predict genotypes (genetic makeup) from a cross. Crossing - over (exchange of genetic material in meiosis) is a separate process not directly shown by Punnett squares. Also, Punnett squares don't indicate the exact number of offspring, just the probability of genotypes.

Answer:

They help predict possible genotypes that result from a cross.