Module 1C

Question 1

What are infectious diseases caused by?

Answer 1

Pathogens - disease causing microorganisms.

Question 2

Explain how pathogens are able to cause symptoms of an infectious disease.

Answer 2

They can directly damage host cells when they are replicating or produce toxins.

Question 3

Each pathogen has what on its surface?

Answer 3

Specific antigens.

Question 4

Because each pathogen has specific antigens what are needed to combat the spread of disease?

Answer 4

Specific antibodies.

Question 5

How exactly do antibodies combat disease?

Answer 5

A type of white blood cell (lymphocyte) will recognise antigens on the surface of pathogens as foreign and will then produce antibodies specific to that antigen.

Each antibody has a unique binding site shape that will be able to lock onto the shape of the antigen.

The antibodies then are able to destroy the pathogen which is then engulfed and digested by macrophages.

Question 6

What else do white blood cells produce to help fight disease?

Answer 6

Antitoxins

Question 7

How come if someone has a disease once, they are unlikely to get it again?

Answer 7

B and T cells create memory cells. These are clones of the specific white blood cells that have remained in the body and carry information about past diseases and have the ability to rapidly produce the necessary antibodies.

Question 8

In what other ways is the body designed for defence against pathogens?

Answer 8

1) Skin is a barrier to pathogens
2) Blood clotting prevents entry of pathogens
3) Mucus in airways traps pathogens
4) Hydrochloric acid in the stomach kills pathogens

Question 9

What are the four types of pathogens and what do they cause?

Answer 9

Fungi - athletes foot
Protozoa - dysentery
Bacteria - Cholera
Viruses - flu

Question 10

What is the difference between a non-infectious and an infectious disease?

Answer 10

An infectious disease can be passed from one person to another easily whereas a non-infectious disease can not.

Question 11

What is passive immunity?

Answer 11

It is when you are given or PASSED someone else’s antibodies.

Question 12

What is active immunity?

Answer 12

It is when your body will make its own antibodies.

Question 13

Explain the process of immunisation.

Answer 13

A harmless pathogen that still contains the antigen proteins on its surface is injected into the patient.

Antigens trigger the normal response of the lymphocytes to produce those specific antibodies.

Immunity will remain because of the memory cells.

Question 14

What are the benefits of immunisation?

Answer 14

Stops you from getting ill and if most people are immunised the disease will be less likely to spread.

Question 15

What are the risks of immunisation?

Answer 15

It’s mostly the short-term side effects; swelling at the injection site, redness, muscle ache and feeling ill for a while after.

Question 16

What were the concerns with MMR and how were they addressed?

Answer 16

A study suggested there was a link between the MMR vaccination and the development of autism. Scientists now know that it is perfectly 100% safe.

Question 17

What does the word parasite mean?

Answer 17

An organism that lives off another organism - the protozoan (plasmodium falciparum)

Question 18

What does the word host mean?

Answer 18

The host is what the parasite will feed off (the human)

Question 19

What does the word vector mean?

Answer 19

It will carry the disease without ever getting it (the mosquito)

Question 20

What causes malaria?

Answer 20

Plasmodium falciparum will cause malaria and the mosquito will carry the plasmodium falciparum.

Question 21

Explain how malaria is spread?

Answer 21

The mosquito will pick up the malarial parasite when they feed on an infected animal. Every time the mosquito feeds on another animal it infects it by inserting the plasmodium into the animal’s blood vessels.

Question 22

How can we stop the spread of malaria?

Answer 22

By looking at the life cycle of the disease and the way in which vectors work to spread the disease we can limit infection.

1) The areas of stagnant water can be drained
2) Fish can be introduced to eat mosquito larvae
3) Insecticides and nets can protect people

Question 23

What is the difference between antibiotics and antivirals?

Answer 23

Antibiotics treat bacterial infections and Antivirals treat virus infections.

Question 24

How do bacteria become resistant to antibiotics?

Answer 24

Misuse of antibiotics e.g over-prescription by doctors or patients not finishing the course can create resistant strains like MRSA the super bug.