What is the purpose of crossing-over in meiosis? A. to create mutations in gametes to increase variation
B. to randomly separate homologous chromosome pairs
C. to reduce the number of chromosomes in gametes by one half
D. to create new combinations of DNA on homologous chromosomes

Which of the following will not cause mass extinction? a. drastic change is weather b. geological change c. both a and b d. none of the above

The term used to describe a disease-causing microorganism isa. virus.b. infection.c. pathogen.d. microbe.e. bacterium.

1. variations in a population of moths allow for some of its members to be able to adapt to environmental changes. the better adapted of the moths will be able to survive the change and thus prevail as the “fittest” of the species. (a) describe three mechanisms in which variation can occur within a species population. (b) explain which mechanism or mechanisms would be responsible for the survival of a population of peppered moths better than white moths in an environment affected by industrial soot. justify your answer.