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.
<span>"Autotrophs are the producers in a food chain, such as plants on land or algae in water" </span>
Answer:
True
Explanation:
The Chesapeake Bay is an example of an estuary that is located in the United States. It is a source of edible marine creatures such as oysters, crabs, prawns e.t.c
Over the years, non - sustainable harvesting of oysters by farmers have been happening at Chesapeake bay, resulting in a reduction in the amount of oysters present.
Waste water
oil pollution
river dumping
marine dumping
Answer:
I can't see the whole question
