Biology - COMMUNICABLE DISEASES (B3)

General Knowledge -

What are communicable diseases?

Diseases that can be spread from one organism to another, caused by pathogens such as bacteria, viruses, fungi, + protists.

General Knowledge -

What is a pathogen?

A microorganism that causes disease.

General Knowledge -

Name the four main types of pathogens.

Bacteria, viruses, fungi, + protists.

Bacterial + Viral Diseases -

How do bacteria cuase disease?

By producing toxins that damage tissues + make us feel ill.

Bacterial + Viral Diseases -

How do viruses cause disease?

They invade cells + reproduce inside them, causing the cell to burst + die.

Bacterial + Viral Diseases -

Name + describe symptoms of one bacterial disease in humans.

Salmonella - Causes food poisoning, symptoms include fever, stomach cramps, vomiting, + diarrhoea.

Bacterial + Viral Diseases -

How is salmonella spread + how is it controlled?

Spread through contaminated food. In the UK, poultry is vaccinated against it.

Bacterial + Viral Diseases -

Name + describe a viral disease in humans.

Measles - Spread by droplets; symptoms include fever + red skin rash. Can be serious, leading to pneumonia / brain infection.

Bacterial + Viral Diseases -

How is measles prevented?

Vaccination, especially as part of the MMR vaccine.

Bacterial + Viral Diseases -

What is TMV and how does it affect plants?

Tobacco Mosaic Virus - causes a mosaic pattern on leaves, reducing photosynthesis + stunting growth.

Fungal + Protist Diseases -

Name one fungal disease in plants.

Rose black spot - causes black / purple spots on leaves, which drop off, reducing photosynthesis.

Fungal + Protist Diseases -

How is rose black spot spread + controlled?

Spread by water / wind; controlled using fungicides + removing affected leaves.

Fungal + Protist Diseases -

Name a protist disease + how it’s transmitted.

Malaria - caused by a protist spread by mosquito vectors.

Fungal + Protist Diseases -

Describe the symptoms + prevention of malaria.

Repeating fever cycles; prevented by insecticides, mosquito nets, + removing stagnant water.

Human Defences -

Name the body’s non-specific defence systems against pathogens.

Skin - barrier + produces antimicrobial secretions.

Nose - traps pathogens w/ mucus + hairs.

Trachea/Bronchi - mucus + cilia to sweep pathogens away.

Stomach - hydrochloric acid kills pathogens.

Human Defences -

What is the role of white blood cells in the immune system?

Phagocytosis - ingest + destroy pathogens.

Antibody production - specific to each pathogen.

Antitoxin production - neutralise toxins.

Vaccination + Drugs -

What is a vaccine + how does it work?

A small amount of dead / inactive pathogen introduced into the body to stimulate white blood cells to produce antibodies.

Vaccination + Drugs -

What are the advantages of vaccination?

Prevents illness, reduces spread in the population (herd immunity).

Vaccination + Drugs -

What are the disadvantages of vaccination?

May cause side effects, doesn’t always give complete immunity.

Vaccination + Drugs -

What are antibiotics + what are they used for?

Drugs that kill / inhibit the growth of a bacteria, but not viruses.

Vaccination + Drugs -

Why don’t anitbiotics work on viruses?

Because viruses live inside cells, making it hard to target them w/out harming body cells.

Vaccination + Drugs -

What is antibiotic resistance + why is it a concern?

When bacteria mutate + survive antibiotic treatment, making infections harder to treat.

Drug Development -

Where were some modern drugs originally extracted from?

Aspirin - willow tree

Penicillin - mould (Penicillin notatum)

Drug Development -

What are the stages of drug-testing?

Preclinical testing - on cells, tissues, animals

Clinical trials (phase 1) - on healthy volunteers for safety

Clinical trials (phase 2 & 3) - on patients to test effectiveness, dosage, side effects

Double-blind trials - neither patient nor doctor knows who has placebo

Drug Development -

What is a placebo + why is it used?

A substance w/ no active ingredient used in trials to test if the real drug has an actual effect.