A-LevelBiologyInfectious diseases9700/22 · Oct/Nov 2025 · Q212 Marks

Cholera is an infectious intestinal disease caused by a bacterial pathogen.

(a)Name the species of bacterium that causes cholera.[1]
(b)The World Health Organization (WHO) recommends a number of different approaches for the prevention and control of cholera. Two of these are: • Authorities should provide access to safe drinking water. • Individuals and communities should practise preventive personal hygiene. Suggest and explain how these two approaches help in the prevention and control of cholera.[4]
(c)(i)Complete Table 2.1 to compare an OCV and passive immunisation for cholera: • fill in the empty box in row 1 • circle the correct answers from the choices given in rows 3, 4 and 5. [Table 2.1][4]
(c)(ii)The production of monoclonal antibodies for treatment involves the formation of hybridoma cells from two different cell types. Name the two types of cell that fuse to form a hybridoma cell and explain why this fusion is necessary.[3]

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2025). The mark or mark type is shown in brackets.

[1] Vibrio cholerae ; must be spelled correctly
[4] any four from: / within general response, in correct context / 1 ref. to, contamination / contaminated ; / A presence of, pathogen / V. cholerae / bacterium in correct context (can look for ora) / 2 ref. to breaking the transmission cycle ; / providing access to safe drinking water / 3 cholera is transmitted by faecal-oral route ; / A described e.g. ref. to (contaminated) faeces and ref. to, food washed in contaminated water / or drinking (contaminated) water / or eating (contaminated) food / practise personal hygiene / 4 ref. to using method to make sure faeces do not enter drinking water; e.g. use of, toilets / latrines / A do not defaecate in or near, rivers / reservoirs / lakes / AW accept urinate / I non-scientific terms for, defaecation / urination / 5 washing hands ; / 6 detail; e.g. use, soap / antibacterial gel / AW / after, urination / defaecation A after going to the toilet / before handling foodscontext is preparation or eating a meal / scrub under fingernails / cafes, restaurants / AW, provide places for washing hands / do not share towels / use disposable towels / AW / 7 AVP; e.g. water, is / should be, chlorinated / boiled / bottled / filtered to remove pathogens / UV-treated / other / water, is / should be, kept separate from sewage / piped direct from water treatment plant / keep fingernails short / safe disposal of vomit
[4] antigen is a standalone mark then move to rows 3,4,5 / if no marks gained from rows 3,4,5, check for correct answers in these rows going down the column to award 1 mark / row 1: oral cholera vaccine - antigen(s); I weak / weakened / toxin / A toxoid / inactivated toxin / R dead antigen / A weakened / attenuated / dead, pathogen / V. cholerae AND passive immunisation for cholera - antibody / row 2: oral cholera vaccine - artificial active AND passive immunisation for cholera - artificial passive / row 3: oral cholera vaccine - yes/no / passive immunisation for cholera - yes (no); / row 4: oral cholera vaccine - shorter / same / longer AND passive immunisation for cholera - longer / same / shorter; / row 5: oral cholera vaccine - shorter / same / longer AND passive immunisation for cholera - longer / same / shorter;
[3] B-lymphocyte / plasma cell / splenocyte, and, myeloma / tumour, cell ; / A B-cell for B-lymphocyte / A cancer cell for myeloma cell / plus two from: / (B-lymphocyte) synthesises (specific / desired) / AW, antibody; I has the antibody / (B-lymphocyte) cannot survive (for long) / dies, in culture ; / (myeloma cell) can divide / can carry out mitosis / long-lived ; / I rapidly / fast / A plasma cell cannot divide / R (hybridoma cell) divides uncontrollably