The diagram shows sections through three blood vessels taken from a human arm. Vessel X was found close to the heart, vessel Y carried blood back from the h...
Question 1 Report
The diagram shows sections through three blood vessels taken from a human arm. Vessel X was found close to the heart, vessel Y carried blood back from the hand, and vessel Z formed a network beside body cells. Scientists measured the relative thickness of the vessel walls before preparing the diagram. The blood in vessel Z moves slowly, allowing exchange with surrounding cells.
(a) Name vessel X. [1]
(b) Describe two structural differences between vessel X and vessel Y. [2]
(c) Explain why vessel Z has a wall that is one cell thick. [2]
Answer Details
(a) Vessel X is an artery. [1]
(b) Vessel X has a thicker muscular and elastic wall than vessel Y. Vessel Y has valves, whereas an artery does not. [2] A vein also has a larger lumen than an artery.
(c) Vessel Z has a wall one cell thick to provide a short diffusion distance. This allows rapid exchange of substances such as oxygen, glucose and carbon dioxide between the blood and body cells. [2]
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