The right answer is vein (it contains blood and has valves).
The infra-cardiac veins of small and medium caliber possess this system of fight against gravity. The valves consist of a dense connective tissue, surmounted by endothelial cells, corresponding to a fold of the intima. They allow blood circulation in the sense organ / heart but prevent venous reflux.
Mitochondria by using cellular respiration to make ATP
Phagocytosis is the process by which immune cells engulf and then destroy bacteria
Answer:
the most random changes of mutation is mainly an organisms physical appearance
A heterogeneous mixture is made of different materials that can easily be separated.
