Immunity, Infection and Forensics

What Immunity, Infection and Forensics covers

Covers how the body is invaded and defended, and how biology is used in forensic work: estimating time of death, DNA profiling, the structure of bacteria and viruses, the immune response, immunity and vaccination, and antibiotic resistance.

The 15 subtopics

Each one has its own page.

• Decomposition, succession and forensic entomologyRecall questions on the stages of decomposition, the succession of insects on a corpse, and how blowfly larvae are used to estimate time since death.Open →
• Body cooling and rigor mortisRecall questions on algor mortis and what changes its rate, and on the biochemical cause and time course of rigor mortis.Open →
• DNA profiling and the polymerase chain reactionRecall questions on what a DNA profile can establish, and on denaturation, annealing and extension in PCR.Open →
• Gel electrophoresisRecall questions on why fragments move towards the positive electrode, why shorter fragments travel further, and how the results are read.Open →
• The structure of bacteria and virusesRecall questions on the bacterial cell wall, plasmids, flagella and capsule, the viral capsid and envelope, and why viruses are acellular.Open →
• Decomposition, and how pathogens enter the bodyRecall questions on saprotrophic nutrition and the role of decomposers, and on the routes by which pathogens get in.Open →
• The body's barriers, and modelling bacterial growthRecall questions on the skin, stomach acid and gut and skin flora, and on using exponential and logarithmic scales for bacterial growth.Open →
• Tuberculosis and HIVRecall questions on how each is transmitted, which cells each infects, how each evades the immune system, and how the infection progresses.Open →
• The non-specific immune responseRecall questions on inflammation, lysozyme, interferons, and the stages of phagocytosis.Open →
• Antigens, antibodies and B cellsRecall questions on antibody structure and how antibodies work, opsonisation, and the roles of plasma and memory B cells.Open →
• T cells and cell-mediated immunityRecall questions on where T cells mature, MHC presentation, and the roles of helper, killer and memory T cells.Open →
• Active and passive immunity, natural and artificialRecall questions on the four combinations, how vaccination works, and why active immunity lasts while passive does not.Open →
• The evolutionary race and pathogen evasionRecall questions on antigenic variation and other evasion mechanisms, and on what the evolutionary race theory proposes.Open →
• Antibiotics and testing their effectivenessRecall questions on bacteriostatic against bactericidal antibiotics, and on measuring the zone of inhibition.Open →
• Hospital acquired infections and their controlRecall questions on the causes of hospital acquired infection, codes of practice for prescribing, and infection control measures.Open →

What you need to know

Answer each one before you reveal it.

Take Immunity, Infection and Forensics further

The same content, four other ways.

Commonly confused

Pairs that lose marks when they are blurred together.

• Antigen vs Antibody

  Antigen: foreign molecule stimulating a specific immune response. Antibody: protein possessing a binding site complementary to a particular foreign molecule.

• Active immunity vs Passive immunity

  Active immunity: protection produced by the person’s own immune response. Passive immunity: protection provided by transferred ready-made proteins.

• Bacterium vs Virus

  Bacterium: prokaryotic cellular pathogen. Virus: acellular infectious particle replicating only inside host cells.

Questions from this topic

Each one with the model answer underneath.

1. 1

   What physical process in a corpse can be examined to estimate time of death?

   Model answer

   The extent of decomposition of the body.

2. 2

   Describe the fresh stage of decomposition.

   Model answer

   The initial stage immediately after death where there is no visible decomposition; internal autolysis begins but external appearance remains largely unchanged.

3. 3

   What characterises the bloat stage of decomposition?

   Model answer

   Gases produced by bacterial metabolism accumulate in body cavities, causing the body to swell and become distended.

4. 4

   What occurs during the active decay stage of decomposition?

   Model answer

   The greatest mass loss occurs as tissues liquefy and are consumed by insects and bacteria; strong odours are released.

5. 5

   Describe the advanced decay stage of decomposition.

   Model answer

   Most soft tissue has been removed; decomposition slows significantly and remaining tissue dries out.

6. 6

   What remains during the dry/skeletal remains stage of decomposition?

   Model answer

   Only bones, cartilage, and dried skin remain; decomposition is very slow at this stage.

What is inside Levo

Six ways to work the same material.

Immunity, Infection and Forensics revision questions

What does Immunity, Infection and Forensics cover in Edexcel A-Level Biology A?

15 subtopics: decomposition, succession and forensic entomology, body cooling and rigor mortis, dna profiling and the polymerase chain reaction, gel electrophoresis, the structure of bacteria and viruses, decomposition, and how pathogens enter the body, the body's barriers, and modelling bacterial growth, tuberculosis and hiv, the non-specific immune response, antigens, antibodies and b cells, t cells and cell-mediated immunity, active and passive immunity, natural and artificial, the evolutionary race and pathogen evasion, antibiotics and testing their effectiveness and hospital acquired infections and their control. Each one has its own page with questions and model answers.

How is Immunity, Infection and Forensics organised?

By the Edexcel 9BN0 specification, subtopic by subtopic, so it matches the order you are taught it in.