AS · 60 marks · 1h 15m. Each generated paper follows the 9700 Paper 2 · AS Structured Questions format, with the same number and style of questions as the real exam, and comes with a Cambridge-style mark scheme.
Generate Paper 2 · AS Structured Questions →DNA replication is semi-conservative.
Explain what is meant by semi-conservative replication.
| Part | Answer and marking points | Marks |
|---|---|---|
| each new molecule has one old and one new strand each new DNA molecule contains one original strand and one newly synthesised strand B2 | 2 |
Describe the roles of B-lymphocytes and T-lymphocytes in the primary immune response to a bacterial infection.
Explain why a vaccine against one strain of influenza may not protect against a new strain.
Explain why antibiotic resistance spreads rapidly in bacterial populations.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | antigen presentation by macrophages; clonal selection of specific T-helper and B cells; T-helper cells release cytokines; B cells divide by mitosis into plasma cells secreting antibodies; memory cells formed; T-killer cells destroy infected cells antigen-presenting cells B1 clonal selection of specific lymphocytes B1 clonal expansion by mitosis B1 T-helper cytokines stimulate B cells B1 plasma cells secrete antibodies B1 memory cells B1 | 6 |
| (b) | antigenic variation: mutation changes antigens, memory cells/antibodies not complementary new strain has different antigens (antigenic variation/drift) B1 existing antibodies/memory cells not complementary B1 | 2 |
| (c) | random mutation gives resistance; selection pressure from antibiotic; resistant bacteria survive and reproduce; plasmids transferred by conjugation (horizontal transmission) mutation B1 selection by antibiotic use B1 horizontal gene transfer on plasmids B1 | 3 |
Mitosis is part of the cell cycle.
Describe the events of metaphase and anaphase.
Explain the role of telomeres.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | chromosomes at equator; centromeres split, chromatids pulled apart metaphase: chromosomes line up at the equator attached to spindle fibres B1 anaphase: centromeres divide B1 sister chromatids pulled to opposite poles B1 | 3 |
| (b) | prevent loss of genes during replication telomeres are repeated sequences at chromosome ends B1 they prevent loss of genes when DNA is replicated B1 | 2 |
Water moves through the leaf by the apoplast and symplast pathways.
Distinguish between the apoplast and symplast pathways.
Explain the role of the Casparian strip in the endodermis.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | cell walls vs cytoplasm via plasmodesmata apoplast: through cell walls and spaces B1 symplast: through cytoplasm and plasmodesmata B1 | 2 |
| (b) | blocks apoplast; water enters symplast suberin blocks the apoplast pathway B1 water and ions must enter the symplast, so uptake is controlled B1 | 2 |
This question is about transport in plants.
Describe the pathways taken by water from the root hair cell to the xylem.
Explain how water moves up the xylem by cohesion–tension.
Describe two features of xylem vessel elements that adapt them for transport.
Describe two features of a xerophyte and explain how each reduces water loss.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | apoplast through cell walls; symplast through cytoplasm and plasmodesmata; Casparian strip forces into symplast at endodermis apoplast pathway through cell walls B1 symplast pathway through cytoplasm via plasmodesmata B1 at the endodermis the Casparian strip blocks the apoplast so water enters the symplast B1 | 3 |
| (b) | evaporation from leaves lowers water potential; water pulled up; H bonds cohesion between water molecules; adhesion to walls; continuous column under tension water evaporates from mesophyll cells and diffuses out of stomata B1 this creates tension that pulls water up the xylem B1 hydrogen bonds between water molecules (cohesion) keep the column continuous B1 adhesion to the xylem walls helps B1 | 4 |
| (c) | no end walls (continuous tube); lignified, waterproof, prevents collapse; pits Any 2 of: no end walls so form a continuous tube; lignified walls withstand tension / prevent collapse; pits allow lateral movement B2 | 2 |
| (d) | rolled leaves / sunken stomata trap humid air; thick cuticle; hairs rolled leaves / sunken stomata / hairs trap moist air, reducing the water potential gradient B1 thick waxy cuticle reduces evaporation B1 | 2 |
This question is about infectious diseases and immunity.
State the causative agent and method of transmission of tuberculosis and of malaria.
Describe the roles of B-lymphocytes and T-lymphocytes in the primary immune response.
Explain how antibiotic resistance spreads in a bacterial population, including horizontal transmission.
Explain how monoclonal antibodies can be used in diagnosis.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | TB: Mycobacterium tuberculosis, airborne droplets; malaria: Plasmodium, female Anopheles mosquito TB: Mycobacterium tuberculosis (or M. bovis) B1 airborne droplets (or undercooked meat / unpasteurised milk) B1 malaria: Plasmodium B1 transmitted by female Anopheles mosquito (vector) B1 | 4 |
| (b) | B: clonal selection, plasma cells secrete antibodies, memory B cells; T helper secrete cytokines stimulating B; T killer destroy infected cells Any 4 of: antigen-presenting cells; specific B cells are selected and divide (clonal expansion); plasma cells secrete antibodies, memory cells remain; T helper cells release cytokines that stimulate B and T killer cells; T killer cells destroy infected cells B4 | 4 |
| (c) | mutation; selection pressure from antibiotic; resistant survive, reproduce; plasmids transferred by conjugation random mutation gives a resistance gene B1 antibiotic kills susceptible bacteria (selection pressure) B1 resistant bacteria survive and reproduce, passing on the allele (vertical) B1 resistance genes on plasmids can pass between bacteria by conjugation (horizontal) B1 | 4 |
| (d) | specific to one antigen; attach marker to detect presence monoclonal antibodies are specific to one antigen B1 with a fluorescent / coloured marker attached they bind and reveal the antigen (e.g. pregnancy test) B1 | 2 |
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Meet Riyaz →Original Cambridge-style practice questions written for mentorriyaz.in. These are not Cambridge past paper questions, and this site is not affiliated with or endorsed by Cambridge University Press & Assessment. Updated 2026-11-04. Paper generator · mentorriyaz.in