B1.1.2 The body's defence system

Question 1

What do bacteria and viruses do that make us feel ill?

Answer 1

Reproduce rapidly inside the body and produce toxins

Question 2

Viruses are unique how?

Answer 2

They damage the cells in which they reproduce

Question 3

How do white blood cells protect the body from pathogens?

Answer 3

• ingesting pathogens
• producing antibodies, which destroy particular bacteria/viruses
• producing antitoxins, which counteract the toxins released by the pathogens

Question 4

What is an antibody?

Answer 4

An antibody is produced by a white blood cell to destroy particular pathogens

Question 5

What is an antitoxin?

Answer 5

An antitoxin counteracts the toxins released by the pathogens

Question 6

What sort of antibodies does the immune system produce?

Answer 6

Specific antibodies to kill a particular pathogen, which leads to immunity

Question 7

What did Semmelweis do?

Answer 7

Recognised the importance of hand washing in the prevention of spreading infectious diseases.

Question 8

What did he insist?

Answer 8

That doctors washed their hands before examining patients. (this lead to a reduction in deaths from infectious diseases)

Question 9

What do painkillers and some medicines do to the body when ill?

Answer 9

Relieve the symptoms of disease, but don’t kill the pathogens

Question 10

What is a pathogen?

Answer 10

A microorganism that causes disease

Question 11

What is an antibiotic?

Answer 11

A medicine that helps to cure bacterial disease by killing infectious bacteria inside the body

Question 12

What can antibiotics not be used for?

Answer 12

Killing viral pathogens

Question 13

Should specific bacteria be treated by specific antibiotics?

Answer 13

Yes

Question 14

What has overuse of antibiotics increased?

Answer 14

Rate of development of antibiotic resistant strains of bacteria

Question 15

What’s MRSA?

Answer 15

A strain of bacteria that has developed resistance to antibiotics

Question 16

Why do bacteria develop resistance to antibiotics?

Answer 16

As a result of natural selection

Question 17

How does the resistance process occur?

Answer 17

• mutations of pathogens produce new strains
• antibiotics may no longer be effective against this new resistant strain
• the new strain will then spread fast as people aren’t immune to it and there is no effective treatment available!

Question 18

What are antibiotics used to treat?

Answer 18

Only serious infections to slow down rate of development in resistant strains

Question 19

How can people be immunised against a disease?

Answer 19

By introducing small dead or inactive quantities of the pathogen into the body (vaccination)

Question 20

How do vaccines work?

Answer 20

They stimulate the white blood cells to produce antibodies that destroy the pathogens. These can be reproduced if the person gets the disease.

Question 21

What is MMR vaccine used to protect children against?

Answer 21

Measles, mumps and rubella

Question 22

What are required for investigating the action of disinfectants and antibiotics?

Answer 22

Uncontaminated cultures of microorganisms

Question 23

How would you conduct the Petri dish testing?

Answer 23

1. sterilise Petri dish and culture media to kill unwanted microorganisms
2. use sterilised inoculating loops (done by passing through flame) to transfer microorganisms to the media
3. close lid of Petri dish with adhesive tape to prevent microorganisms from the air contaminating the culture
4. incubate cultures at a max of 25c