Two main causes of disease are pathogens and lifestyle.

• Pathogens include bacteria, virus and fungi.
• They’re infectious and can easily spread from one host to another.
• Pathogens can damage their host by reproducing and releasing toxins.
• Some diseases are caused by lifestyle and so are preventable.
• If two variables are correlated they act in the same way.
• Correlation doesn’t mean that two variables have a causal relationship. Experiments looking at the variables need to prove this.

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TEST IT!

1. Pathogens spread infectious diseases.

a) Provide two ways in which a pathogen can be transmitted from one host to another.

i. _____________________________________________
ii. _____________________________________________

b) Provide two ways in which a pathogen can cause disease within its host:

i._________________________________________________
ii. ________________________________________________

2. Cervical cancer happens within the neck of the uterus. A group of scientists decided to investigate the link between cervical cancer and a number of Human Papilloma Virus (HPV) infections.

The table below shows their results.

A local newspaper released the headline: Cervical cancer is caused by HPV.

a) Does this data support this? Explain your answer.

b) Some people are more at risk than others to get cancer. Provide two risk factors associated with cancer, one which can be controlled and one which can’t.

3. A number of diseases carry risk factors connected with lifestyle.

a) What is a risk factor?

b) Name two risk factors connected with coronary heart disease.

i. __________________________________________________
ii. __________________________________________________

ANSWERS

a) Answers include:

i. direct contact
ii. water
iii. aerosol droplets
iv. food
v. animal bites

b)

i. reproduction
ii. releasing toxins

2.

a) Answers include:

i. Yes, many women with cervical cancer have HPV 16 and some have HPV 18
ii. No, not many women with cervical cancer have HPV 6 and 11
iii. HPV doesn’t mean causation: another factor could be involved or the relationship could be a coincidence
iv. There’s no control group involved
v. Not all HPV types were included
vi. Having cervical cancer might increases a woman’s susceptibility to HPV infection
vii. Not all women with cervical cancer have HPV
viii. A woman might have more than one type of HPV

b) Answers include:

i. Controlled factors: diet, exercise
ii. Uncontrolled: genes, ages

3.

a) Anything that affects your chances of getting a disease

b) Answers include:

i. diet
ii. exercise
iii. genetics
iv. age