Microbiology and Pathogens | Edexcel A-Level Biology B (9BI0)

Microbiology and Pathogens

191 questions
13 subtopics
Topics 5 to 7, examined on Paper 1 and Paper 3
Paper 1 and Paper 3

How microorganisms are cultured and measured, how bacteria and other agents cause disease, how antibiotics work and why resistance spreads, and the specific and non-specific ways the body responds to infection..

It covers culturing microorganisms and aseptic technique, measuring bacterial growth, the bacterial growth curve, bacteria as pathogens, the action of antibiotics, antibiotic resistance, other pathogenic agents, controlling endemic disease, phagocytosis and the humoral response, the cell-mediated immune response, memory cells and the secondary response, natural and artificial immunity and vaccination and herd immunity.

Sample questions from Microbiology and Pathogens

Answer each one closed book first, then open the answer.

Culturing microorganisms and aseptic technique

At what temperature are microorganisms incubated in school laboratories, and why?

Show the answer
25°C, to reduce the risk of growing human pathogens, which grow best at temperatures closer to 37°C.
Measuring bacterial growth

What is the purpose of a calibration curve in turbidity measurements?

Show the answer
It relates absorbance to cell concentration, allowing turbidity readings to be converted to cell numbers.
Bacteria as pathogens

Which genus of bacteria is associated with pathogenicity through exotoxin production?

Show the answer
Staphylococcus species.
The action of antibiotics

Why do bacteriostatic antibiotics require a functional host immune system to be effective?

Show the answer
Because they only halt bacterial growth; the host immune system must then eliminate the bacteria.
Other pathogenic agents

Besides respiratory droplets, how else can influenza virus be transmitted?

Show the answer
By contact with contaminated surfaces followed by touching the mouth, nose or eyes.
Controlling endemic disease

What is the purpose of epidemiological studies in assessing malaria control methods?

Show the answer
They analyse patterns of disease incidence and transmission in populations to determine whether control interventions reduce malaria cases and mortality.
The cell-mediated immune response

Why is the lymphocyte response described as specific?

Show the answer
Each lymphocyte carries membrane receptors of one particular shape, so it can bind to and respond to only one type of antigen.
Memory cells and the secondary response

How does the lag phase of the secondary immune response compare to that of the primary response?

Show the answer
The lag phase is shorter in the secondary response.

The 13 subtopics

One subtopic is one session. Work down the list.

Subtopic	What it covers	Questions
Culturing microorganisms and aseptic technique	Recall questions on aseptic technique with loops, flames and lids, sterilising media and what they must contain, agar, broth and selective media, incubation temperature, safety and ethics, and streak plating to isolate pure colonies.	24
Measuring bacterial growth	Recall questions on total and viable counts, dilution plating, turbidity, and the haemocytometer.	12
The bacterial growth curve	Recall questions on the lag, log, stationary and death phases and their causes, the growth rate constant k and how to calculate it, generation time, and why logarithms are used to plot bacterial growth.	14
Bacteria as pathogens	Recall questions on how bacteria damage the host through toxins and invasion, with named examples.	14
The action of antibiotics	Recall questions on bactericidal and bacteriostatic antibiotics, how penicillin inhibits transpeptidase and causes osmotic lysis, how tetracycline blocks protein synthesis at 70S ribosomes, and why these antibiotics spare human cells.	17
Antibiotic resistance	Recall questions on how resistance arises by mutation and spreads by natural selection, vertical transmission, conjugation, transformation, transduction and R-plasmids, the misuse that accelerates it, and the control measures and why each is limited.	19
Other pathogenic agents	Recall questions on how stem rust fungus spreads and damages wheat, how influenza virus is transmitted, enters cells and causes symptoms, and how Plasmodium is transmitted and causes cyclical fever, anaemia and cerebral malaria.	18
Controlling endemic disease	Recall questions on the social and economic implications of controlling endemic malaria, the ethics of consent, equity and environmental harm, how peer review, clinical trials and epidemiology validate control methods, and the control methods themselves.	17
Phagocytosis and the humoral response	Recall questions on phagocytosis by neutrophils and macrophages, antigen-presenting cells, where lymphocytes mature, the humoral response through T helper cells, cytokines, clonal selection and expansion, plasma cells, and antibody structure and action.	18
The cell-mediated immune response	Recall questions on antigens and antigen-presenting cells, why the lymphocyte response is specific, how it differs from the humoral response, and the roles of T helper, T killer and T memory cells in destroying infected cells.	9
Memory cells and the secondary response	Recall questions on how B and T memory cells persist and respond on re-exposure, and how the secondary response compares with the primary response in speed, lag, peak antibody concentration and duration.	8
Natural and artificial immunity	Recall questions on the four combinations of active and passive, natural and artificial immunity, with examples of each.	9
Vaccination and herd immunity	Recall questions on how the safe antigen in a vaccine activates B and T cells and produces memory cells, the secondary response on later exposure, herd immunity and its threshold, and what happens when vaccination rates fall.	12

Microbiology and Pathogens is 191 of the 2,073 questions in the guide.Get the guide, £8

How the guide is worked

Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.

Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.

Read the full method, the return schedule and the research behind it.