Which of these causes sickle-cell anemia? (1 point) O base pair deletion
O too few chromosomes
O too many chromosomes
O base pair substitution

(amoeba sisters video recap: pedigrees and need

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

Explain how paleontologists use trilobite fossils as index fossils for various geologic time periods.