Which of the following events does not occur during prophase?
a. identifiable chromosomes appear.
b. the nuclear envelope begins to fragment.
c. chromatin in the nucleus condenses.
d. chromosomes replicate themselves.

What are four key elements of the study of economics?

Select the correct answer from each drop-down menu. in an experiment, dr. travis examined the effects of calcium intake on osteoporosis, a condition that causes an increased risk of bone fractures. the amount of calcium is variable. the risk of bone fractures .

What does the hardy-weinberg principle relate to? a. chances of survival of an organism b. frequency of alleles in a population c. natural selection in a species d. causes of evolution among organisms