Biology 3

Question 1

Infections are caused whenever a foreign pathogen invades an organism. There are four main types of pathogen: what are these?

Answer 1

Viruses
bacteria
fungi
protists

Question 2

What are viruses?

Answer 2

Viruses are tiny, non-living (do not contain cells) particles that can reproduce rapidly within the body.

Question 3

More info on Viruses?

Answer 3

Viruses invade host cells and use them to make new virus particles. Once the new virus particles are made, they cause the cells to burst. The cell damage is what makes a person feel ill.

Question 4

what is bacteria?

Answer 4

Bacteria are small living cells that damage cells directly or by producing toxins (poisons).

Question 5

In what conditions can bacteria reproduce?

Answer 5

Warm
Moist
Good supply of oxygen

Question 6

What is fungi?

Answer 6

Fungi are single-celled organisms that have a body made up of hyphae (thread-like structures).

Question 7

What is the hyphae able to do?

Answer 7

The hyphae are able to grow and penetrate tissues, such as human skin or the surface of plants. The hyphae produce spores that can spread to other plants and animals.

Question 8

what are protists?

Answer 8

Protists are single-celled eukaryotic organisms (they have a nucleus). Many are parasites, meaning that they live on or inside other organisms.

Question 9

The spread of infections can be prevented by?

Answer 9

Being hygienic
Isolating infected individuals
Protecting against vectors
Vaccination

Question 10

Hygiene helps because…

Answer 10

By being hygienic, we can destroy pathogens or wash them away so that they are not spread.

Question 11

Isolation

Answer 11

By isolating infected individuals, we prevent contact with other organisms. This stops the infection from spreading.

Question 12

Protecting against vectors

Answer 12

Some protist diseases are carried by vectors. A vector is an organism that carries pathogens without being infected.

We can protect against mosquitos carrying malaria using mosquito nets.

Question 13

Vaccination

Answer 13

Vaccination can make people immune to (resistant to) infection. The more individuals that are vaccinated, the less likely the disease is to spread.

Question 14

Drug testing tests three main criteria:

Answer 14

Toxicity - is it safe?
Efficacy - does it work?
Dose - how much is needed?

Question 15

Drug testing involve?

Answer 15

pre-clinical testing and clinical testing.

Question 16

Stage 1 - Pre-clinical testing

Answer 16

Scientists carry out early-stage testing on human cells and tissues grown in the laboratory or other live animals.

In the UK, new medicines have to undergo tests on two different live mammals to assess how toxic a drug is to cells.

If a drug damages cells at the pre-clinical stage, it will likely fail and not go the next stage of testing.

Question 17

Stage 2 - Clinical testing

Answer 17

In clinical testing, drugs are tested on healthy volunteers and patients to check that they are safe. Usually, low doses of the drug are used.