How did the cessation of crossing-over contribute to the disparity between the X and Y chromosomes? What will be an ideal response?


ANSWER: In most chromosomes, crossing-over is a way to make sure that subtle changes are regularly
exchanged and that major differences do not accumulate. In the X and Y chromosomes, the
slow accumulation of a region in which crossing-over did not occur prevented genetic
exchange between the two and resulted in each evolving differently. It is very similar to
taking a population and separating it - each will accumulate its own unique mutations and
these will slowly create a significant difference between the two.

Biology & Microbiology

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During the cardiac cycle, when a heart chamber is relaxed, it is in ____________________ and when it is contracting, it is in ____________________

Fill in the blank(s) with correct word

Biology & Microbiology

Enzymes used to cut DNA molecules in recombinant DNA research are

a. ligases. b. restriction enzymes. c. transcriptases. d. DNA polymerases. e. replicases.

Biology & Microbiology

Explain how and why the following circumstances influence characteristics of temperature-induced DNA melting:

percentage of GC base pairs urea (forms hydrogen bonds with bases) sodium chloride (neutralizes negatively charged phosphates) What will be an ideal response?

Biology & Microbiology

The number of chromosome pairs in a species:

a) is always 23. b) is greatest among insects. c) is always greater than three. d) increases with intelligence. e) None of the above are true.

Biology & Microbiology