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.

answer; i believe that the correct answer is ; males are hemizygous for the x chromosome;

the potatoes have high sugar concentrations and although these potatoes were different we could seethe effects that their sugar concentrations had in different environments. for example, the potatoes in sample a, were placed in pure water. this created a hypertonic environment and caused the potatoes to draw in water from its surroundings. we saw the opposite happen with the potatoes in sample b when placed in the sodium chloride solution. the potatoes in this case were in a hypotonic solution and therefore lost water to their surroundings.