Module 7 - Infectious Diseases

Question 1

List the causes of infectious diseases.

Question 2

How are diseases transmitted?

Question 3

Define health.

Answer 3

‘A state of complete physical, mental and social well-being, and not merely the absence of disease or infirmity.’

Question 4

Why is the concept of health so subjective?

Answer 4

Because if the WHO definition was taken literally it would be very difficult to achieve a healthy status, as health is relative to ourselves and others.

Question 5

List the 6 types of pathogens.

Answer 5

Prions, viruses, bacteria, fungi, protozoans, ectoparasites and endoparasites.

Question 6

What could be classified as a disease if the definition was taken literally? Why?

Answer 6

Pregnancy, broken bones and old age.

Question 7

What is a prion?

Answer 7

A protein capable of causing disease.

Question 8

Do all prions cause disease? Explain and give examples of the diseases they cause.

Answer 8

No, in order for a prion protein to cause disease a mutation must occur in its genetic code. The resulting disease is called a spongiform disease because it eats away at the hosts brain tissue, causing sponge like holes. Examples include; Kuru and Creutzfeldt Jakob Disease (CJD) - all these diseases are fatal.

Question 9

Are viruses living or nonliving?

Answer 9

They have characteristics of both living and nonliving organisms. They contain genetic material and can pass on hereditary information but are not composed of cells.

Question 10

How does a virus reproduce?

Answer 10

First, the virus attaches itself to a cell and injects nucleic acid into it. It then takes over the cell and uses it to create copies of its DNA. The DNA is then used to create new copies of the virus. The cell will continue to replicate the virus until it becomes so full of copies it bursts and dies, releasing the viruses into the body.

Question 11

What are the 5 different types of bacteria?

Answer 11

Coccus (spherical), bacillus (a rod), spirillum (spiral), vibrio (comma) and rickettsiae (oval).

Question 12

How does bacteria work?

Answer 12

It releases enzymes to break down and consume cell contents.

Question 13

What is bacteria?

Answer 13

A single-celled prokaryotic organism. It contains a cell wall but no membrane bound nucleus/organelles.

Question 14

How does bacteria reproduce? Is this sexual or asexual?

Answer 14

Asexually, through binary fission.

Question 15

What is a protozoan?

Answer 15

A single-celled eukaryotic organism. They have a cell membrane, no cell wall and possess a membrane bound nucleus/organelles.

Question 16

How do protozoans reproduce? Is this sexual or asexual?

Answer 16

Asexually, through binary fission.

Question 17

List the 4 types of protozoans. Briefly explain them.

Answer 17

Flagellates (have a long tail for swimming), ciliates (covered in microscopic hairs to assist movement), amoeba (have projections of the cytoplasm to assist movement) and sporozoa (have no structures for motion and reproduce via spores).

Question 18

What are some characteristics of fungi?

Answer 18

They are eukaryotic organisms that possess a cell wall, but differ in composition to a plant cell. They can be unicellular (yeasts) or multicellular (mushrooms). Fungi can be microscopic or macroscopic and reproduce sexually or asexually.