IAL Biology Specification Checklist for Unit 4 Topic 6

Understand the principles and techniques involved in culturing microorganisms using aseptic technique .

Understand different methods of measuring microorganism growth : cell counts , dilution plating , mass and optical methods (turbidity) .

Understand the phases of a bacterial growth curve ( lag , exponential , stationary , death ) and calculate exponential growth rate constants .

Investigate the rate of growth of microorganisms in liquid culture, ensuring safe and ethical use of organisms.

(i) Compare structures of bacteria and viruses ( nucleic acid , capsid , envelope ) using examples – Ebola , TMV , HIV , λ phage .
(ii) Understand lytic and latency cycles.

Understand how Mycobacterium tuberculosis and HIV infect human cells, causing symptoms that may result in death.

(i) Know the major routes pathogens use to enter the body.
(ii) Understand protective barriers – skin , stomach acid , gut and skin flora .

Understand non-specific responses – inflammation , lysozyme action , interferon and phagocytosis .

Understand roles of antigens and antibodies in the immune response , including plasma cells , macrophages and antigen-presenting cells .

Understand differences between B cells ( B memory , B effector ) and ( T helper , T killer , T memory ) in the immune response .

Understand development of immunity – natural , artificial , active and passive .

Understand the ‘ evolutionary race ’ between pathogens and hosts, supported by pathogen evasion mechanisms .

Understand the difference between bacteriostatic and bactericidal antibiotics .

Investigate the effect of different antibiotics on bacteria .

Know how understanding causes of hospital-acquired infections led to codes of practice for antibiotic prescription and infection control .

Know roles of microorganisms in decomposition of organic matter and carbon recycling .

Know how DNA can be amplified using the polymerase chain reaction (PCR) .

Know how gel electrophoresis separates DNA fragments of different lengths.

Understand how DNA profiling is used for identification and determining genetic relationships in organisms.

Understand how to determine time of death using decomposition , succession , forensic entomology , body temperature and muscle contraction.

EDEXCEL IAL BIOLOGY

Specification 2025 - 2026

Unit 4

Topic 6 – Microbiology, Immunity and Forensics

6.1 Culturing Microorganisms

6.2 Measuring Growth of Microorganisms

6.3 Bacterial Growth Curve

6.4 CORE PRACTICAL 13

6.5 Structure of Bacteria and Viruses

6.6 Infection by Mycobacterium tuberculosis and HIV

6.7 Pathogen Entry and Barriers to Infection

6.8 Non-Specific Responses to Infection

6.9 Antigens and Antibodies

6.10 Roles of B Cells and T Cells

6.11 Development of Immunity

6.12 Evolutionary Race between Pathogens and Hosts

6.13 Bacteriostatic and Bactericidal Antibiotics

6.14 CORE PRACTICAL 14

6.15 Hospital-Acquired Infections

6.16 Role of Microorganisms in Decomposition

6.17 Polymerase Chain Reaction (PCR)

6.18 Gel Electrophoresis

6.19 DNA Profiling

6.20 Determining Time of Death

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