Immunity and Vaccination

Question 1

What is an antigen?

Answer 1

A protein on the surface of a pathogen

Question 2

Which type of blood cell is involved in the immune system?

Answer 2

The white blood cell

Question 3

Describe the process of phagocytosis

Answer 3

1. A phagocyte will detect a pathogen which is secreting chemicals and will move closer to it
2. The phagocyte will then engulf and ingest the pathogen
3. The phagocyte then produces enzymes to digest and kill the pathogen
4. This process is called phagocytosis

Question 4

Describe how lymphocytes help to defend against pathogens?

Answer 4

1. The lymhpocyte will detect the specific protein antiGENS from a pathogen
2. This stimulates the lymphocyte to produce and release specific antiBODIES which bind onto the antiBODIES
3. The antiBODIES cause the pathogens to clump together and destroys them
4. Then the lymphocytes remain in the blood as MEMORY CELLS
5. Now, in the case of a second infection of the same pathogen, the memory cells can produce and release pathogens MORE rapidly and fight against the pathogens more strongly

Question 5

Which part of the immune system is involved in making us immune to pathogens?

Answer 5

The lymphocytes

Question 6

Describe how we become immune to pathogens
and why we show no symptoms after a secondary infection

Answer 6

1. The immunesystem detect the foreign antigens on the surface of the pathogen
2. This stimulates the lymphocyte to produce and release specific antibodies
3. The antibodies bind onto the antigens and make the pathogens clump together and destroys them
4. Then the lymphocytes remain in the blood and memory cells
5. So now in the case of a second infection of the same pathogen the memory cells can produce and release the same SPECIFIC antibodies to destroy the pathogens before they cause cell damage so we don’t show symptoms

Question 7

What do antitoxinsdo to help defend against pathogens?

Answer 7

1. Bacterial pathogens secrete toxins which cause cell damage
2. The white blood cell will detect the chemical toxins being released and then produce and release a specific antitoxin
3. This antitoxin will bind to the toxin and neutralise it before it can cause any cell damage

Question 8

Why don’t the pathogens used in vaccines make us feel ill?

Answer 8

Because the pathogens are dead or inactive

Question 9

Explain how vaccines prevent illness in an individual

Answer 9

1. A dead or inactive form of the pathogen in injected into the body
2. The stimulates the lymphocytes to produce and release specific antiBODIES which will bind to the protein antiGENS on the surface of the pathogen
3. The antibodies will destroy the pathogen
4. Then the lymphocytes divide by mitosis to replicate themselves
5. These lymphocytes will remain in the blood for decades and so when a pathogen re-enters the body then the lymphocytes can produce and release antibodies more quickly and in large quantities to prevent pathogens from causing cell damage and so no symptoms develop

Question 10

Explain how the spread of pathogens is reduced by immunising a large proportion of the population

Answer 10

With mass vaccination, it means that majority of the population is immune to the disease
This prevents the virus from spreading around and infecting people
This causes the virus to eventually disappear
This means that people who are not vaccinated will not get infected by the virus- this is herd immunity

Question 10

Although it is dead/inactive forms of pathogens used in vaccines why is it that the white blood cells still produce the correct antibodies?

Answer 10

Because the dead/inactive pathogens still have the same protein antigens on their surface

Question 10

Is phagocytosis a specific or non-specific process in the immune system?

Answer 10

Non-specific

meaning they just engulf any pathogens

Question 11

Are antibodies from lymphocytes specific or non-specific?

Answer 11

Specific

Question 12

Are antitoxins from white blood cells specific or non-specific?

Answer 12

Specific