Genes can sometimes be exchanged between homologous chromosome pairs. this process is known as crossing-over. which of the following statements is true of crossing-over? a. crossing-over always results in a non-beneficial mutation. b. the gene for eye color can be exchanged with the gene for hair color during crossing-over. c. crossing-over contributes to genetic diversity or variation. d. only one gene may be exchanged at a time during crossing-over.

C. Crossing-over contributes to genetic diversity or variation.

Explanation:

Crossover is a genetic event that represents a natural and reciprocal exchange of fragments between homologous chromatids. This event enables a high rate of gene recombination, with increased genetic variability in reproductive cells (gametic: egg and sperm), causing in addition to the mixing of paternal and maternal chromosomes inherited from parental generation (P), also the exchange of alleles over these inherited chromosomes (Branch Generation 1), transmitted to the following descendants (Branch Generation 2).

Genotypically and phenotypically, crossing-over collaborates significantly, providing the differences of one species. Otherwise, for example, since the dawn of the human species, if it were not for this process, we would all be clones, genetically identical organisms.

any abiotic or biotic factor in an ecosystem that causes a population's size to slow or decrease is a limiting factor.