Đặc điểm chung nào của động vật nguyên sinh vừa đúng cho loài sống tự do lẫn loài sống kí sinh

In which situations is the principle of cross-cutting relationship useful in determining relative age?

Is there any species that went extinct in recent years due to natural causes (not caused by human interaction). if so, what caused it?

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