Ralph is looking at a blood vessel under a microscope as part of his study about the cardiovascular system. he notices that the vessel contains blood and has valves. what is the blood vessel that he is observing?
a. capillary
b. vein
c. lymph
d. artery

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.

b. vein

Vein is a blood vessel that exhibit thin muscular walls and it brings the deoxygenated blood  from all the cells, tissues and organs back to the heart. In the veins the valves are present which prevent the backward flow of blood. Lumen of the vein is wide.

According to the above information vein is the correct option.

question: which statement best describes the different properties of metals?

answer: they are shiny and bend without breaking.

since metals have certain characteristics properties, they include the following: they are ductile, malleable, shiny, hard, lustrous, flexible and they are good conductor of heat and electricity. so therefore, metals are not dull and they are not non-flexible as listed. instead, they are shiny and flexible.

hope this , have a good day. c;

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