B1: Pathogens, Fighting Disease, Vaccinations and Drugs

Question 1

What are the two main types of pathogens?

Answer 1

Bacteria and viruses

Question 2

How do bacteria make you feel ill?

Answer 2

They damage your cells and produce toxins

Question 3

What are bacteria?

Answer 3

They are very small cells which can reproduce rapidly inside the body.

Question 4

What are viruses?

Answer 4

They are not cells and are tiny.

Question 5

What do viruses do?

Answer 5

1. They replicate themselves by invading the cells and using the cells’ machinery to produce many copies of themselves
2. The cell will usually burst, releasing all the new viruses
3. The cell damage causes you to feel ill

Question 6

In what ways is the body adapted to protecting you from foreign microorganisms?

Answer 6

1. Skin, hairs and mucus in the respiratory tract stops organisms getting inside the body
2. There are platelets in the blood that clot blood to seal wounds quickly
3. White blood cells attack microorganisms when they are in the body.

Question 7

How do white blood cells kill microorganisms?

Answer 7

1. The consume them-they engulf foreign cells and digest them
2. They produce antibodies
3. They produce antitoxins

Question 8

How does a white blood cell kill foreign cells using antibodies?

Answer 8

1. Invading cells have antigens on their surfaces
2. When a white blood cell comes across the foreign antigen, it will produce proteins (antibodies) to kill the invading cells. The antibodies produced are specific to that type of antigen
3. Antibodies are then rapidly produced and carried around the body to kill all similar bacteria/viruses
4. If the person is infected by the same foreign cell again the person will be immune so they won’t get ill when the white blood cell attacks it.

Question 9

How does a white blood cell kill foreign cells using antitoxins?

Answer 9

They produce antitoxins that counter the toxins produced by the invading cell.

Question 10

How does a vaccination work?

Answer 10

1. They involve injecting a dead or inactive version of the microorganisms
2. Although the antigens are harmless, the white blood cells produce antibodies to attack them.
3. Because white blood cells remember how to attack antigens if they have already entered the body before, the person will become immune
4. If the live microorganism enters the body now, the person will not become ill because the white blood cells will rapidly produce antibodies to kill off the pathogen.

Question 11

Why are booster injections sometimes needed?

Answer 11

Some vaccines wear off over time so booster injections are given to increase levels of antibodies again.

Question 12

What are the advantages of vaccinations?

Answer 12

1. Vaccines have helped to control lots of infectious diseases
2. Epidemics can be prevented if a large percentage of the population is vaccinated. Even the people who have not been vaccinated are unlikely to catch the disease because there are fewer people ale to pass it on.

Question 13

What are the disadvantages of vaccinations?

Answer 13

1. They don’t always work

2. People can react badly to a vaccine but it is rare

Question 14

What is an epidemic?

Answer 14

A big outbreak of a disease.

Question 15

What is a pandemic?

Answer 15

When a disease spread around the world.

Question 16

What are painkillers?

Answer 16

Drugs that relieve pain but they do not actually tackle the cause of disease, just help to reduce symptoms.

Question 17

What are antibiotics?

Answer 17

A drug that actually kills or prevents the growth off bacteria, causing the illness, without killing the body’s cells.

Question 18

Why don’t antibiotics kill viruses?

Answer 18

Viruses reproduce inside/using the body’s cells, which makes it very difficult to develop drugs that will only destroy the virus and not the body’s cells.

Question 19

How can bacteria become resistant to antibiotics?

Answer 19

1. Bacteria mutates and these mutations can cause them to become resistant to an antibiotic
2. This means that only the non-resistant strains of bacteria will be destroyed
3. The resistant bacteria will survive and reproduce so its population will increase
4. The resistant strain could cause a serious infection that cannot be treated by antibiotics

Question 20

How can the rate of development of resistant strains of bacteria be slowed down?

Answer 20

Doctors need to avoid over-prescribing antibiotics