an example of a single-gene trait is

a. bands on a snail’s shell.
b. beak size in the galápagos finches.
c. length of snails.
d. fur color in cats.

which of the following explains why the edges of africa and south america fit together like two pieces of a puzzle?

a. endosymbiosis
b. biological forces
c. continental drift
d. none of the above

I’m doing some practice exam questions for biology, and i’m not sure how to do these 3 parts to the question.

How can antibodies "remember" a particular bacterial invader or "antigen" on that invader?

Which statement describes characteristics of planarians? a they live in oceans, are parasites, and reproduce only sexually. b they live in fresh water, are parasites, and reproduce only asexually. c they live in oceans, are free living, and reproduce sexually and asexually. d they live in fresh water, are free living, and reproduce sexually and asexually.