Genetics of Disease (Medical Interventions)

Unit 1: Unit 1.1 Outbreak InvestigationMI 1.1Biotechnology Research and Experiments

Classify Pathogens

Use infection evidence to classify pathogens step by step.

Builds on (2 levels back)inferred · high confidence

Transmission basics: Outbreak work depends on agent, host, route, time, and place.
Case definition: Students need a rule for who counts as a case before counting cases.

Prerequisites are inferred: pending teacher review.

Re-learn the skill with worked practice and clear examples.

Classify a pathogen by matching its described features to the rows of the feature table.

Step 1: List the clues

From the case, pull out whether the agent is a cell and whether it needs a host. Add any extra clue such as 'single cell.'

Agent	Cell?	Needs host?
Bacterium	yes	no
Virus	no	yes
Fungus	yes	sometimes
Parasite	yes	yes

Step 2: Match to a row

Run each clue across the table until only one row fits all of them. That row is your classification.

Step 3: Name the limit

Two rows can share a feature (for example, several agents need a host). When clues overlap, say which extra test would tell them apart instead of guessing.

Practice

Use the table. A lab agent is a single cell, and it can reproduce on its own without entering any host. Which class is it?

Approved

Agent	Cell?	Needs host?
Bacterium	yes	no
Virus	no	yes
Fungus	yes	sometimes
Parasite	yes	yes

A.Virus
B.Bacterium
C.Parasite
D.It cannot be classified

Show the worked solution ▾

Answer: B. Bacterium

Step 1: Use 'single cell': Being a cell rules out the virus row, which says 'no' under Cell?.
Step 2: Use 'no host needed': Among the cells, only the bacterium row says 'no' under Needs host?. Fungus says 'sometimes' and parasite says 'yes.'

Why it's right: A single cell that needs no host matches only the bacterium row in the table.

Why the others miss:

A: A virus is not a cell, so 'single cell' rules it out.
C: A parasite needs a host, but this agent needs none.
D: The two features given are enough to land on exactly one row, so it can be classified.

Aligned to Biotechnology Research and Experiments · reading level ~grade 9

Use the table. A microbe is a cell that reproduces only when it is living inside a human host. Of the cell-type agents, which row matches BOTH 'is a cell' AND 'Needs host? = yes'?

Reviewed

Agent	Cell?	Needs host?
Bacterium	yes	no
Virus	no	yes
Fungus	yes	sometimes
Parasite	yes	yes

A.Virus
B.Bacterium
C.Parasite
D.None of the rows

Show the worked solution ▾

Answer: C. Parasite

Step 1: Keep only cells: Drop the virus row because it is not a cell.
Step 2: Keep 'Needs host? = yes': Of the remaining cells, bacterium says 'no' and fungus says 'sometimes.' Only the parasite row says 'yes.'

Why it's right: Parasite is the only row that is a cell and has 'yes' under Needs host?, matching the description.

Why the others miss:

A: A virus is not a cell, so it is ruled out first.
B: A bacterium needs no host, so it does not match 'needs a host.'
D: The parasite row fits both features, so one of the rows does match.

Aligned to Biotechnology Research and Experiments · reading level ~grade 9

Where you'd see this

In Unit 1.1 Outbreak Investigation, this skill turns class evidence into a result another person can check.

Careers that use this

Epidemiologist: Uses classify pathogens to make a decision from evidence without overclaiming.

Video library

Watch: Classify Pathogens

GCSE Biology – Pathogens: Bacteria, Viruses, Fungi and Protists

KayScience

Guided notes

Fill these in as you work through the lesson.

Big idea: You can sort a disease-causing agent into bacterium, virus, fungus, or parasite by checking a few features: is it a cell, and does it need a host cell to copy itself?

Key terms: write the meaning

Pathogen (an agent that makes you sick):
Bacterium (a living single cell that can copy on its own):
Virus (not a cell; it must take over a host to copy):
Parasite (a cell or organism that lives on or in a host and harms it):

The rule

If the agent is not a cell and cannot copy itself without invading a host, it is a . If it is a single cell that needs no host to reproduce, it is a .

Check yourself

Using the table, name one feature that separates a virus from a bacterium.
Which two agent types in the table both need a host?
An agent is a single cell but only grows inside another organism. Which two types could it be?

Work one example

Read the table. An unknown agent is NOT a cell and CANNOT reproduce unless it is inside a host cell. Walk down the 'Cell?' and 'Needs host?' columns and decide which class it is.