(i) Outline what is meant by the term “ring strain”.

(ii) On the diagram above, label with asterisk/s (*) the carbon atom/s that experience ring strain.

(i) Some antibiotic-resistant bacteria produce a beta-lactamase enzyme which destroys penicillin activity. Suggest how adding clavulanic acid to penicillin enables the antibiotic to retain its activity.

(ii) Populations of antibiotic-resistant bacteria have increased significantly over the last 60 years. Outline why antibiotics such as penicillin should not be prescribed to people suffering from a viral infection.

i

bond angles smaller/distorted
OR
instability resulting from abnormal bond angles
OR
bond angles «approximately» 90° instead of 109.5°/120°

Accept “109/110°” for “109.5°”

ii

asterisks (*) on all 3 lactam ring carbon atoms

Must mark all 3 carbon atoms.
Ignore asterisks on the RHS carbon atoms of the five-membered ring.

i

beta-lactam/four-membered ring «in clavulanic acid» reacts with enzyme/beta lactamase

Accept “acts as enzyme inhibitor/suicide substrate/preferentially binds to enzyme”.

ii

antibiotics not effective against viruses
OR
viruses have no cell wall/cell structure/target structures to attack

increasing exposure of bacteria «to antibiotic» increases resistance

Accept “antibiotics kill beneficial bacteria” for M2.