Topic 5 – Health, Disease and the Development of Medicines- Causes of Disease

Question 1

define health

Answer 1

A state of complete physical, mental and
social well-being (as defined by the
World Health Organization, WHO)

Question 2

define disease

Answer 2

A disorder of the body or mind that

negatively affects an individual’s health

Question 3

What are the two types of disease?

Answer 3

communicable

non communicable

Question 4

What is a communicable disease?

Answer 4

A disease that is passed directly between individuals

Caused by a pathogen

Question 5

define pathogen

Answer 5

A disease-causing organism e.g. virus, fungi, bacteria, protists

Question 6

What is a non-communicable disease?

Answer 6

disease that cannot be transmitted between individuals
generally long lasting with slow onset
caused by lifestyle, environmental and genetic mutations

Question 7

what is a symptom?

Answer 7

change experienced by an organism that indicates disease

Question 8

why does having an illness make an individual more likely to contract another disease?

Answer 8

A disease may weaken an individual’s immune system making them increasingly susceptible to other infections

Question 9

describe chlorea

Answer 9

caused by Vibrio cholerae bacterium
Spread by drinking water or washing in water that has
been contaminated with infectious faeces
Symptoms: diarrhoea, vomiting

Question 10

how can the incidence of cholera be reduced?



Answer 10

access to clean water
Improved sanitation (sewage disposal etc.)

Question 11

Describe tuberculosis (TB)

Answer 11

caused by Mycobacterium tuberculosis bacterium
It is an airborne bacteria spread by droplet infection
Symptoms: lung damage, chesty cough, wheezing

Question 12

how can the transmission of TB be reduced?



Answer 12

improved hygiene (washing hands, sneezing into tissues etc.)
Infected individuals should avoid crowded areas
Increased ventilation in the individual’s home

Question 13

Describe Chalara ash dieback

Answer 13

Caused by a fungus that infects ash trees
Spread via airborne spores which are carried by the wind
Causes dark lesions on bark and blackened leaves which wilt and eventually die

Question 14

How can the transmission of Chalara ash dieback disease be reduced?

Answer 14

Control the movement of ash trees
Kill infected plants
Replant with a different species

Question 15

Describe malaria

Answer 15

Caused by plasmodium protist
Spread by mosquito vectors which pick up the plasmodium protist when feeding on the blood of an infected organism and transmit malaria to other organisms during feeding
Flu-like symptoms, damage to red blood cells, liver damage

Question 16

How can the incidence of malaria be reduced?



Answer 16

Mosquito nets
Insect repellant
Cover arms and legs

Question 17

Describe stomach ulcers

Answer 17

Caused by Helicobacter pylori bacterium
Transmitted orally by eating infected foods or drinking infected water
Symptoms: stomach pain, vomiting, nausea

Question 18

How can the transmission of Helicobacter pylori be reduced? (biology only)

Answer 18

Access to clean water
Improved hygiene
improved sanitation (sewage disposal etc.)

Question 19

Describe ebola

Answer 19

Caused by Ebola virus
Spread by direct contact with infected body fluids e.g. blood, semen, saliva, mucus, vomit
symptoms: fever, diarrhoea, vomiting, internal bleeding

Question 20

How can the transmission of Ebola be reduced

Answer 20

Improved hygiene
isolating infected individuals
Sterilisation of outbreak areas

Question 21

Describe simply how viruses cause disease

Answer 21

They enter host cells and replicate inside of them. The host cells rupture, releasing new viruses.

Question 22

How do viruses differ from other microorganisms e.g. bacteria, fungi?

Answer 22

Viruses are not living organisms. They do not reproduce and can only replicate inside a host cell.

Question 23

By what two pathways do viruses replicate inside living cells?

Answer 23

● Lytic pathway

● Lysogenic pathway

Question 24

Describe the lytic pathway

Answer 24

1. Virus binds to specific receptors on host cell
2. Virus injects its DNA into host cell and replicates its DNA using host cell machinery
3. New viral structures are produced and assembled
4. Host cell ruptures, releasing new viruses

Question 25

Describe the lysogenic pathway

Answer 25

1. Virus binds to specific receptors on host cell
2. Viral DNA injected into host cell and becomes integrated into host cell genome
3. Viral DNA replicates each time the host cell divides. However, the cell remains normal.
4. Trigger causes the activation of viral DNA. It enters lytic pathway

Question 26

Describe HIV

Answer 26

● Caused by human immunodeficiency virus
● Spread by direct contact with infected body fluids e.g. blood,
semen, breast milk.
● Destroys white blood cells making the individual immunodeficient and increasingly susceptible to other diseases. Leads to AIDS.

Question 27

How can the spread of HIV

Answer 27

Use of condoms and protected sex
Needle exchange
Screening blood for HIV
Deterring infected mothers from breastfeeding

Question 28

Describe Chlamydia

Answer 28

Caused by Chlamydia bacterium
spread through sexual contact or direct contact with
infected genital fluids
Can result in infertility

Question 29

how can the transmission of Chlamydia be reduced?



Answer 29

Use of condoms and protected sex Screening