Compare how mild and strong analgesics relieve pain in the body.

Identify the amine functional group in the morphine molecule below by drawing a ring around it.

State the name of the functional group found in heroin but not in morphine.

State one advantage and one disadvantage of using morphine as a strong analgesic.

mild analgesics function by intercepting the pain stimulus at the source / interfere with the production of substances that cause pain/prostaglandins;

strong analgesics work by bonding to receptor sites in the brain / prevent the transmission of pain impulses without depressing the central nervous system;

any circle around the nitrogen atom / the nitrogen atom and its three neighboring atoms;

ester;

Advantage: antidiarrheal/constipation (in treatment of diarrhea) / reduces coughing;

Disadvantage: addiction / tolerance / risk of overdose;

Most candidates were able to distinguish between the ways mild analgesics and strong analgesics relieve pain in part (b).

A substantial number of candidates failed to identify the tertiary amine in the structure of morphine. Candidates were inaccurate in drawing a circle around the amine group in part (c). Either just the nitrogen atom or nitrogen atom with its three neighbouring atoms should have been circled.

A large number of candidates confused the ester with an ether or carbonyl group as the functional group found in heroin but not in morphine.

Most candidates recognized the disadvantage of using morphine but they had extreme difficulty in stating a specific advantage for using morphine as a strong analgesic.