Past paper/exam questions from AQA a level biology papers since 2017 on immunity topic 2 for AQA A level Biology 2023 exam. As a student for the University Of Oxford, taking into consideration questions/subtopics that were present in previous years for AQA A level biology we filtered AQA questions ...
(b) 1. Water potential in (bacterial) cells higher (than in honey) / water potential
in honey lower (than in bacterial cells);
Q candidates must express themselves clearly
1. Must be comparative e.g. high WP in cell and low WP in
honey
2. Water leaves bacteria / cells by osmosis;
3. (Loss of water) stops (metabolic) reactions.
3. Needs a reason why lack of water kills the cell
3
[5]
Q2.
(a) QWC
1. (Phagocyte engulfs) to form vacuole / vesicle / phagosome;
Accept surrounds bacteria with membrane
Q3.
(a) 1 macrophages present antigens to B lymphocytes;
2 antigen binds to / is complementary to receptors on lymphocyte;
3 binds to a specific lymphocyte;
5 (B) lymphocytes reproduce by mitosis / (B) lymphocytes cloned;
6 plasma cells secrete antibodies;
4 max
(b) 1 restriction enzyme / endonuclease;
2 to cut plasmid / to form sticky ends in plasmid;
3 (use) ligase(to join) gene to plasmid;
4 culture bacteria with (in medium containing) plasmids
5 to allow uptake of plasmids / transformation;
6 use of cold shock / chemical treatment (to enhance uptake) / heat
shock;
(ignore bullets / electroporation / microinjection)
3 max
[7]
Q4.
(a) (Micro)organism that causes disease / harm to body / an immune response;
Accept: named microorganism that causes disease
Allow infection
1
(b) 1. Phagocyte attracted by a substance / recognises (foreign) antigen;
Accept named substance eg chemical / antigen
5. Lysosome contains enzymes;
Accept named example of enzyme
6. Pathogen digested / molecules hydrolysed;
Neutral: Destroyed
4 max
(c) 1. Antigens (on pathogen) are a specific shape / have specific tertiary / 3D
structure;
Structure alone is insufficient
2. Antibody fits / binds / is complementary to antigen / antibody-antigen
complex forms;
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