T3 - Communicable diseases

Question 1

What are pathogens?

Answer 1

Pathogens are microorganisms that enter the body and cause disease.

Question 2

Examples of pathogens:

Answer 2

Viruses, bacteria, protists and fungi.

Question 3

Are pathogens communicable or non communicable?

Answer 3

Communicable

Question 4

What do pathogens infect?

Answer 4

Animals and plants

Question 5

What are the 3 main ways of spreading pathogens?

Answer 5

Direct contact, water, air

Question 6

Water

Answer 6

Some pathogens can be picked up by drinking or bathing in dirty water.
Eg. cholera is a bacterial infection that’s spread by drinking in dirty water contaminated with the diarrhoea of other sufferers.

Question 7

Air

Answer 7

Pathogens can be carried in the air then breathed in.
Some airborne pathogens are carried in the air in droplets produced when you cough or sneeze.
Eg. influenza

Question 8

Direct contact

Answer 8

Some pathogens can be picked up by touching contaminated surfaces, including the skin.
Eg. athletes foot (commonly spread by touching the same things as an infected person, public swimming baths)

Question 9

What are the 4 main ways of preventing diseases?

Answer 9

Being hygienic, destroying vectors, isolating infected individuals, vaccination.

Question 10

Hygiene

Answer 10

Doing things like washing your hands can prevent the spread of disease.

Question 11

Destroying vectors

Answer 11

By getting rid of the organisms that spread disease, you can prevent the disease from being passed on.
Vectors that are insects can be killed using insecticides or by destroying their habitat so that they can no longer breed.

Question 12

Isolation

Answer 12

If you isolate someone who has a communicable disease it prevents them from passing it on to anyone else.

Question 13

Vaccination

Answer 13

Vaccinating people and animals against communicable diseases means that they are less likely to develop the infection and then pass it on to someone else.

Question 14

What are viruses?

Answer 14

Not cells or living organisms.
10,000 x smaller than animal or plant cells.

Question 15

How do viruses spread?

Answer 15

They live inside cells and replicate themselves using the cells machinery to produce many copies of themselves.
The cell then bursts releasing all the new viruses.
This cell damage is what makes you feel ill.

Question 16

Measles

Answer 16

Measles is spread by droplets from an infected persons sneeze or cough.
Symptoms: red skin rash, fever
Most people are vaccinated when they are young.
Can be fatal, very serious, can lead to pneumonia or inflammation of the brain.

Question 17

HIV

Answer 17

Human Immunodeficiency Virus.
Spread by sexual contact or by exchanging bodily fluids.
Symptoms: Flu-like
Can be controlled by antiretroviral drugs.
The virus affects the immune cells.
Infection with the HIV virus can lead to aids. This is where the immune system is so weak that the person can’t cope with other infections or cancers.

Question 18

Tobacco mosaic virus

Answer 18

Affects plants (tomatoes)
Parts of the leaves become discoloured, causes a mosaic pattern.
The discolouration means the plants can’t carry out photosynthesis as well so the virus affects growth and the plant won’t be able to produce as many sugars.

Question 19

What diseases are caused by bacteria?

Answer 19

Salmonella, gonorrhoea

Question 20

What diseases are caused by viruses?

Answer 20

Measles, HIV, Tobacco mosaic virus

Question 21

What is bacteria?

Answer 21

Very small living cells.
They make you feel ill by producing toxins that damage your cells and tissues.

Question 22

Salmonella

Answer 22

Type of bacteria that causes food poisoning.
Symptoms: Fever, diarrhoea, stomach cramps, vomiting.
Symptoms are caused by the toxins that the bacteria produce.
Salmonella food poisoning is caused by eating food that has been contaminated.

Question 23

Gonorrhoea

Answer 23

Sexually transmitted disease (STD)
Passed on by sexual contact (unprotected sex)
Caused by bacteria
Symptoms: pain when urinating, thick yellow or green discharge from the vagina or penis.
Originally treated with penicillin however strains of the bacteria have now become resistant to it.
To prevent the spread: antibiotics and barrier methods of contraception (condoms).

Question 24

Which communicable diseases are eukaryotic organisms?

Answer 24

Fungi, Protists, animals, plants

Question 25

Rose black spot

Answer 25

Rose black spot is a fungal disease that causes purple or black spots develop on leaves, which then often turn yellow and drop off.
This reduces photosynthesis and so also reduces the growth of the plant.
It can be spread by water, or the wind.
Treatment involves spraying the infected plants with fungicides, or destroying the affected leaves.

Question 26

What are protists?

Answer 26

Eukaryotes, mostly single-celled
Some protists are parasites. (Parasites live on or in other organisms and can cause them damage)
They are often transferred to the organism by a vector which doesn’t get the disease itself.

Question 27

Malaria

Answer 27

Malaria is a disease caused by a protist. The mosquitoes are vectors - they pick up the malarial protist when they feed on an infected animal.
Every time the mosquito feeds on another animal, it infects by inserting the protist into the animals blood vessels.
Malaria causes repeated episodes of fever. It can be fatal.
People can be protected from mosquitoes using insecticides and mosquito nets.

Question 28

What is fungi?

Answer 28

Some are single celled, others have a body made up of hyphae (thread like structures). These hyphae can grow and penetrate human skin and the surface of plants, causing diseases.
They hyphae can produce spores which can be spread to other plants and animals.