B. some species die out when environmental changes occur
Answer:
Blood cells are produced in the bone marrow of the body more specifically they become blood cells from first being stem cells which then divide until they reach a mature red blood cell stage. ( or other types of cells, stem cells are like the blank template for either red blood cells, white blood cells, or platelettes.)
Explanation:
The pyloric sphincter is compose of smooth muscle and is located between the pylorus in the stomach and duodenum of the small intestine. In digestion, it serves as a valve controlling the flow of food thus it prevents the contents of small intestine backing up into the stomach.
Nucleus, ribosomes, endoplasmic reticulum, and <span>Golgi apparatus.</span>
