Pathogens, Defence against Disease and the Immune Response.

Question 1

What do microbiologists do?

Answer 1

They study microorganisms. They identify pathogens, suggest appropriate treatments for infections, and oversee infection control measures.

Question 2

What may infectious diseases be caused by?

Answer 2

Viruses
Bacteria
Fungi
Protoctistans

Question 3

How can infectious disease be transmitted?

Answer 3

Through the air (droplet infection)
By direct contact, including sexual contact
Through food and water
By vectors.

Question 4

Describe the reproduction of microorganisms.

Answer 4

They reproduce rapidly in the body.

Question 5

What do microorganisms produce?

Answer 5

Toxins.

Question 6

When are microorganisms more likely to cause disease?

Answer 6

If large numbers enter the body.

Question 7

How does the skin prevent the entry of pathogens?

Answer 7

Acts as a natural barrier.

Question 8

How does mucus in the respiratory passages prevent the entry of pathogens?

Answer 8

It traps some pathogens.

Question 9

How do cilia on the cells in the respiratory passages prevent the entry of pathogens?

Answer 9

Moves the mucus and trapped pathogens up to the throat.

Question 10

How does acid conditions in the stomach, vagina and urethra prevent the entry of pathogens?

Answer 10

Kills some pathogens.

Question 11

How does our ability to produce scabs prevent the entry of pathogens?

Answer 11

They prevent pathogens from getting in at the site of wounds.

Question 12

How do white blood cells prevent infectious disease?

Answer 12

They combat the pathogens.

Question 13

How did Alexander Fleming discover penicillin?

Answer 13

He accidentally left out a bacterial culture on a petri dish without the lid. He noticed there were bacteria growing over the whole plate, except in a clear area around some mould. Fleming realised that a chemical in the mould was killing the bacteria. Florey and Chain cultured various varieties of mould and picked which produced the most penicillin.

Question 14

How do bacteria become resistant to antibiotics?

Answer 14

When infected an antibiotic is used to kill a bacteria, but sometimes there is a mutation, which may not have otherwise survived because the other bacteria were outnumbering it, but when they are killed the bacteria has all the food and space it needs to respire and they survive and reproduce, producing an antibiotic resistant strain.

Question 15

What do lymphocytes do in response to an infection or a vaccine?

Answer 15

They produce antibodies.

Question 16

What is active immunity?

Answer 16

When antibodies are produced more rapidly following the primary infection or vaccine, because the body recognises the pathogen.

Question 17

What is passive immunity?

Answer 17

When antibodies are injected when a person has been exposed to a dangerous infective organism.

Question 18

What is the immune response stimulated by?

Answer 18

Particular antigens.

Question 19

What are antigens?

Answer 19

Foreign substances which are usually protein-based, found on cell surface membranes and virus coats.

Question 20

What does the immune response involve?

Answer 20

The production of specific antibodies.

Question 21

When is the immune response slow?

Answer 21

When the body has not previously encountered the relevant antigen.

Question 22

When is the immune response rapid?

Answer 22

When in the presence of an immunological memory in the form of specific lymphocytes.

Question 23

What did Edward Jenner do?

Answer 23

He noticed that milk maids who caught cow pox, did not suffer from small pox. So he realised something in cowpox protects against smallpox.
He took pus from blisters on the hand of a milkmaid with cowpox and transferred pus to scratch on skin of a healthy boy. Boy suffered mild symptoms of cowpox but soon recovered, Jenner then infected boy with pus containing smallpox on two occasions, and on neither occasion did the boy show signs of infection. Some scientists were not convinced so he did more tests on other people including his son.

Question 24

What can vaccines be prepared from?

Answer 24

Complete pathogens which are killed by heat or chemicals so they are harmless.
Separating parts of the pathogen, e.g. the antigens
Culturing the pathogen and selecting strains which do not cause the disease.

Question 25

What must be done once the vaccine has been prepared?

Answer 25

It must be tester on tissue culture, and animals to show it stimulates antibody production without damaging tissue.

Question 26

What is done after animal testing?

Answer 26

It is tested on large numbers of human volunteers.

Question 27

Why is it tested on human volunteers?

Answer 27

To determine whether there are any unusual reactions, rare side effects and possible faulty batches of the vaccine.