Communicable Diseases

A microorganism that causes infectious disease.

Viruses, bacteria, protists and fungi.

Inside the cells of a living host.

Toxins (poisons).

They live and reproduce inside cells, which causes cell damage.

Yes.

Direct contact, by water and by air.

It sends out droplets containing pathogens, which other people breathe in.

An organism that carries a pathogen from one host to another.

The mosquito that carries malaria.

Wash hands with soap and water.

It stops them passing the pathogen to other people.

It breaks the link between infected and healthy hosts.

It makes people immune, so they cannot catch or pass on the disease.

They reproduce rapidly inside the body, so their numbers rise fast.

Name the three types of pathogen shown, and a fourth that is missing.

Virus (reproduces inside cells), bacterium (divides rapidly and makes toxins), protist (single-celled eukaryote) and fungus (grows as threads).

A fever and a red skin rash.

By inhaling droplets from the sneezes and coughs of an infected person.

It can be a serious illness and can be fatal if complications arise.

Human immunodeficiency virus.

A flu-like illness.

The body's immune cells.

Late-stage HIV infection, when the immune system is too damaged to deal with other infections or cancers.

By sexual contact and by the exchange of body fluids, such as blood when drug users share needles.

Antiretroviral drugs.

A widespread virus that affects many plants, including tomatoes.

It gives it a mosaic pattern of discolouration.

Less photosynthesis takes place, because parts of the leaf have lost chlorophyll.

Tobacco mosaic virus.

Use condoms, avoid sharing needles and treat infected people with antiretroviral drugs.

Many illnesses cause similar symptoms, so a blood test is needed.

Label each virus and say what it does.

Measles: fever and red rash. HIV: attacks immune cells, late stage AIDS. Tobacco mosaic virus: mosaic pattern on leaves, less photosynthesis.

In food, or on food prepared in unhygienic conditions.

Fever, abdominal cramps, vomiting and diarrhoea.

The bacteria and the toxins they secrete.

Poultry are vaccinated against it.

Cook food thoroughly, wash hands, or keep raw and cooked food apart.

A sexually transmitted disease caused by a bacterium.

A thick yellow or green discharge and pain when urinating.

By sexual contact.

By treating with antibiotics and using a barrier method of contraception, such as a condom.

Penicillin.

Many resistant strains have appeared.

A sexually transmitted disease.

Passing bacteria from raw food or dirty surfaces to other food.

To kill any salmonella bacteria.

Salmonella food poisoning.

Describe how each disease is spread and controlled.

Salmonella is spread by poultry, raw food and undercooked meals, and is controlled by vaccinating poultry and hygiene. Gonorrhoea is spread by sexual contact and is controlled by condoms and antibiotics, although some strains are resistant.

A fungus.

Purple or black spots on the leaves, which often turn yellow and drop early.

The damaged leaves photosynthesise less.

By water and by wind.

With fungicides, and by removing and destroying the affected leaves.

A protist.

Recurrent episodes of fever. It can be fatal.

The mosquito.

It takes up protists when it bites an infected person and passes them on when it bites someone else.

Prevent mosquitoes breeding, and use mosquito nets.

In standing water.

They stop people being bitten.

No. It only carries the protist.

Rose black spot.

A chemical that kills fungi.

Name the part marked X and say what it does in spreading malaria.

The mosquito. It is the vector that carries the protist from an infected person to a healthy person.

Describe each step in the spread of malaria.

An infected person. A mosquito bites and takes up the protists. The mosquito, the vector, carries them. It bites a new person and passes them on. Nets and draining breeding sites control it.