Paper 3 · November 2023 · Transport and Gas Exchange
Unlike an artery, a vein has
Aa thicker wall overall and a narrower lumen.
Bno lumen at all, since blood flows through solid tissue.
Cvalves along its length and a thinner wall relative to its lumen.
Da thicker tunica media containing more smooth muscle.
Explanation
Since blood pressure in a vein is low, its wall (including the tunica media) is thin relative to its wide lumen, and it has valves at intervals to stop blood flowing backwards.
Derived from ZIMSEC Biology 6030/3 Paper 3, November 2023, Q7