Which phrase best describes the process of crossing over? a. pairs of homologous chromosomes exchange segments
b. pairs of sister chromatids exchange segments
c. pairs of homologous chromosomes become linked
d. pairs of sister chromatids become linked

How can scientists test their ideas about the origin of the universe if they can't physically interact with or study?

Which of the following is the earliest era of earth's geologic time scale? cenozoic mesozoic precambrian paleozoic

4. if a cell is placed inside a solution that has a higher concentration of solute than on the inside of the cell, what can be said about the movement of water? a. water will move out of the cell, causing it to shrivel. b. water will move in and out of the cell at the same rate. c. water will move out of the cell, causing it to swell. d. water will move into the cell, causing it to swell.