Which type of mutation plays the most important role in increasing the number of genes in the gene pool? A. Changes in nucleotide sequence that lead to natural selection removing the allele from the population
B. Point mutation with a change in one base resulting in a harmful phenotype
C. Rearrangement of gene loci due to deleting or disrupting chromosomes
D. Gene duplication allowing for mutations to accumulate and expand the genome over generations

What have we learned from fossil evidence about evolution? a) it is an abrupt change. b)the process is observable. c) it takes place during one lifetime only. d)the most complex traits are always selected.

The earth's oceans are made up of chlorine, and trace elements. a) carbon, oxygen b) oxygen, silicon c) hydrogen, oxygen d) nitrogen, oxygen

Imagine a self-reactive t cell that has not undergone clonal deletion in the thymus (that is to say, it has escaped central tolerance). if it encounters self antigen in the absence of an infection or inflammation, what will happen to this self-reactive t cell? (select two answers) (a) the t cell undergoes clonal expansion. (b) the t cell gains effector functions. (c) the t cell undergoes apoptosis. (d) the t cell becomes activated. (e) the t cell becomes anergic.