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C3.2.9—Clones of plasma cells

Clones of plasma cells explains how a specific barrier, pathogen interaction, immune mechanism or treatment response contributes to protection against infectious disease.

Syllabus
First assessment 2025
Objective
C3.2.9
Level
HL

Exam analysis

Chance of appearing4%of analysed past papers
Latest appearanceNovember 2019
Most common paperPaper1
Typical marks1

Common command terms

  • Identify
  • State

Scoring notes

Common mistake
Confusing plasma cells, memory cells and helper T-cells in the activation sequence.

Recent exam appearances

November 2019Paper1 ["HL"] · TZ037[ 1 ]C3.2.9—Clones of plasma cells
November 2018Paper1 ["HL"] · TZ037[ 1 ]C3.2.9—Clones of plasma cells
November 2017Paper2 ["HL"] · TZ02(c)[ 1 ]C3.2.9—Clones of plasma cells
May 2014Paper1 ["HL"] · TZ135[ 1 ]C3.2.9—Clones of plasma cells
May 2012Paper1 ["HL"] · TZ235[ 1 ]C3.2.9—Clones of plasma cells
Practice this objective

Coverage 2012–2019 · Updated 16 Jul 2026

Plasma cells are antibody factories made by clonal selection

Because only a small number of B cells recognize a given antigen, an activated B cell divides repeatedly by mitosis to form a large clone.

Clonal expansion supplies enough plasma cells to secrete an effective quantity of one antibody type. Every plasma cell in the clone inherits the selected antibody specificity.

Rare matching B cell → activation → repeated mitosis → clone of genetically matching cells → many plasma cells secrete the same specific antibody; some cells can become memory cells.

A selected B cell responding to a bacterial surface antigen produces thousands of plasma-cell descendants, all releasing antibodies complementary to that antigen.

Antibodies are secreted in quantity by differentiated plasma cells, not by every inactive B cell. Mitosis increases cell number without changing specificity.

Clones of plasma cells

Assessment in practice

1 marks
How it is assessed

This objective is assessed through multiple choice, commonly using Identify / State.

Command terms

Identify / State

What earns marks

Mark schemes repeatedly reward named details, correct sequence and clear distinctions between similar processes.

Watch for

Confusing plasma cells, memory cells and helper T-cells in the activation sequence.

Representative question

Question 1

[Maximum number: 1]

What is a role of activated B cells?

A

Secrete antibiotics in response to specific antigens

B

Activate T cells in the immune response

C

Release histamine in response to allergens

D

Multiply to form clones of plasma cells

Defence Against Disease

  • Skin, mucus, cilia, lysozyme and clotting form primary barriers against pathogens.
  • Innate immunity is rapid and broad: phagocytes recognize, engulf and digest pathogens. Adaptive immunity is antigen-specific and forms memory.
  • Helper T-cells coordinate responses; activated B-cells undergo clonal selection, producing antibody-secreting plasma cells and memory cells. A second exposure therefore triggers a faster, stronger response.
  • HIV infects CD4 helper T-cells; their loss weakens immune coordination and can lead to AIDS.
  • Antibiotics target bacterial processes, not viruses. Antibiotic exposure selects resistant variants, which can spread by reproduction or plasmid transfer.
  • Vaccination creates active artificial immunity; high population immunity can indirectly protect susceptible people.
  • Evaluate disease and vaccine claims using reliable sources, trends, controlled comparisons, incidence and efficacy—not raw totals alone.

Concept essentials

  • Clones of plasma cells has to be linked to the exact pathogen, cell, molecule or population process involved.
  • The biological effect of clones of plasma cells depends on the sequence from trigger to protective outcome.
  • Clear distinctions within clones of plasma cells prevent confusion with neighbouring immune responses.
  • Evidence for clones of plasma cells is strongest when mechanism and consequence are explained together.