Differentiation requires of particular genes to produce cell populations with capabilities that form tissues. a. inactivation; unlimited b. inactivation; limited c. activation; limited d. activation; unlimited

Some birds look for food near cattle and other livestock. the movement of the cattle churns up the ground, making insects available to the birds. the cattle appear to be unaffected by the presence of the birds. what kind of relationship exists between the birds and the cattle? o a. parasitism o b. commensalism o c. predation o d. mutualism

Which statement describes a way in which the digestive and excretory systems work together? a. the nephrons absorb nutrients from food going to the large intestine. b. the excretory system balances blood gases in the small intestine. c. the intestinal villi filter blood and send wastes to the bladder. d. the excretory system balances the salts and water obtained from digested food

Choose the correct words to complete the sentences related to genetic screening. is a procedure that is used during pregnancy to detect genetic defects. is extracted from the uterus and used to identify genetic disorders?