Secreted antibodies
a. plasma cells
b. t cells
c. t cells
d. natural killer cells

Which of the following statements is true? a. the main cause for speciation is an increase in gene flow. b. organisms that reproduce asexually are not considered part of a species. c. on a tree of life diagram, speciation is shown by the merging of two different lineages. d. the size of the geographic area inhabited by a population can cause speciation.

The organelle pictured is found in cells of and is theorized to have once been an independent organism.

If bacteria are much too small to see, what is one reason why can we see colonies in the petri dishes that have plenty of food to eat after only a few days?