The biological significance of crossing over is that it
Correct answer: D. produces new combinations of alleles on the same chromosome
- A. keeps linkage groups permanently intact
- B. halves the chromosome number of the gametes
- C. ensures that all gametes are genetically identical
- D. produces new combinations of alleles on the same chromosome
Explanation
Exchange between non sister chromatids creates chromosomes carrying combinations of alleles that neither parent had, and this recombination is a major source of the variation natural selection works on. Halving the chromosome number is the job of the reduction division itself, not of crossing over. Crossing over does the opposite of keeping linkage groups intact, since it breaks linkage up.
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About Gene Linkage and Crossing Over
Linked genes lie on the same chromosome and tend to pass together, unlike genes that assort independently on different chromosomes. The topic connects linkage with homologous pairing, crossing over during prophase I of meiosis, recombinant and parental offspring, and recombination frequency as an estimate of gene distance.
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