A hospital scientist compares two blood vessels taken from different parts of a donated human body. Fig. 1 shows their cross-sections at the same magnificat...
Question 1 Report
A hospital scientist compares two blood vessels taken from different parts of a donated human body. Fig. 1 shows their cross-sections at the same magnification. Vessel P carries blood away from the heart.
(a) Name vessel P. [1]
(b) Name vessel Q. [1]
(c) Describe two visible differences between P and Q. [2]
(d) Explain why vessel P has a thicker wall. [2]
(e) State the function of the structure shown inside vessel Q. [1]
(f) Which vessel, P or Q, is more likely to contain blood at the lowest pressure? [1]
Answer Details
(a) P is an artery. [1] It carries blood away from the heart.
(b) Q is a vein. [1]
(c) P has a thicker wall than Q, and P has a narrower lumen. Equivalently, Q has a wider lumen and contains a valve. [2]
(d) Arterial blood is pumped from the heart at high pressure. The thick muscular and elastic wall resists this pressure and prevents the vessel bursting. [2]
(e) The valve in Q prevents backflow of blood. [1]
(f) Q, the vein, is more likely to contain blood at the lowest pressure. [1]
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