3. what important event occurs during prophase i of meiosis that does not happen in mitosis?
a. replication of dna
b. crossing over between homologous chromosomes
c. the nuclear envelope disappears
d. formation of spindle fibers
4. what occurs during crossing over?
a. two complete chromatids switch places
b. chromosomes move the other side of the cell
c. portions of homologous chromosomes interchange
d. chromosome number is cut in half

How did the research presented in the article affect scientists' understanding of the evolution of eukaryotes

4.06 hc)a five-year review of threats to the southern resident orca population of the united states concluded that the top threats were prey availability, contaminants, and effects from recreational and whale watching vessels. further down the list are oil spills, disease, and effects from commercial vessels not targeting whales. how might this list be different if it were for transient whale populations, which have a larger average population size and live farther offshore in open waters? a)the transient population is more likely to be affected by contaminants. b)the transient population is less likely to be affected by whale watching vessels. c)the transient population is more likely to be affected by disease. d)the transient population is less likely to be affected by prey availability.

Look at the following answer choices and determine which belongs in the both category. testable, can be disproven explains natural phenomena, has evidence to support it prediction, tentative, one or more scientists working together well established, many different scientists working independently, highly reliable