Infectious diseases, Immunity, Antibiotics and Painkillers

Question 1

Why do pathogens make us feel ill?

Answer 1

They release toxins, viruses also damage our cells

Question 2

Where do viruses reproduce?

Answer 2

Inside cells

Question 3

What is the name of the “marker” which indicates where a cell comes from?

Answer 3

An antigen

Question 4

What do white blood cells produce when they detect a foreign antigen?

Answer 4

Specific antibodies

Question 5

What do phagocytes do to pathogens?

Answer 5

They engulf and ingest them

Question 6

What is in a vaccine?

Answer 6

Dead or inactive pathogen

Question 7

What does MMR protect you against?

Answer 7

Measles, Mumps and Rubella

Question 8

What do antibiotics destroy

Answer 8

Bacteria

Question 9

Can a painkiller destroy bacteria?

Answer 9

No, it only treats symptoms

Question 10

How does MRSA develop?

Answer 10

Natural Selection For a longer answer: Bacteria mutate or there is variation in bacteria. This leads to bacteria /resistant cells that survive an antibiotic. These antibiotic resistant cells go on to reproduce developing more antibiotic resistant cells.

Question 11

Hand-gel dispensers are now placed at the entrance of most hospital wards. Explain why. (2 marks)

Answer 11

Kills / destroys bacteria / MRSA. Prevents / reduces transfer of bacteria.

Question 12

Explain fully why antibiotics cannot be used to cure viral diseases. (2 marks)

Answer 12

Viruses live inside cells. Viruses are inaccessible to antibiotics

Question 13

A recent study found that babies in 90 % of hospitals are infected with the MRSA bacterium. Explain how the MRSA bacterium has developed resistance to antibiotics. (2 marks)

Answer 13

A mutation occurs which is no longer recognised by antibiotics.

Question 14

Explain how Semmelweiss’s results could be used to reduce the spread of MRSA in a modern hospital. (2 marks)

Answer 14

People wash hands after contact with patient so bacteria / pathogen / MRSA not transferred to other patient

Question 15

Antibiotic-resistant strains of bacteria are causing problems in most hospitals. Explain, as fully as you can, why there has been a large increase in the number of antibiotic-resistant strains of bacteria. (4 marks)

Answer 15

• overuse of antibiotics - bacteria mutate - antibiotics kill non-resistant strains or idea of selection - reduced competition - resistant bacteria reproduce

Question 16

Explain, as fully as you can, how the MMR vaccine protects children from these diseases (3 marks)

Answer 16

any three from: - vaccine is inactive / dead form of (pathogen) - stimulates antibody production - stimulates antitoxin production by white cells - antibodies kill (pathogen) - antitoxins neutralise poisons - antibodies quickly produced on reinfection

Question 17

Explain why it is difficult to treat diseases caused by viruses. (2 marks)

Answer 17

any two from - live inside / infect body cells - difficult for drugs to enter (body) cells / drug would kill (body) cell - antibiotics ineffective against viruses - viruses mutate frequently

Question 18

A person can be immunised against a disease by injecting them with an inactive form of a pathogen. Explain how this makes the person immune to the disease. (3 marks)

Answer 18

It stimulates antibody production by white cells. If later on, the live pathogen gets into your body, white blood cells recognise it and rapidly produce the antibodies. These antibodies destroy the pathogens before they can make you ill.

Question 19

Which 3 ways do white blood cells help to protect us from pathogens?

Answer 19

engulf and ingest pathogens produce antibodies produce antitoxins

Question 20

What is Aseptic technique and how do we culture bacteria safely? (6 marks)

Answer 20

To culture microorganisms, they need a culture medium called agar jelly. This contains the nutrients needed for growth. They should be incubated at 25∘C in school labs. They also need oxygen. Taping the plate at 4 points allows this to get in. To keep the culture pure you must pass metal loops through a flame, boil solutions and agar. Also prevent microorganisms getting in from the air.

Question 21

What is the jelly called in the petri dish which we grow bacteria on?

Answer 21

Agar

Question 22

What temperature do we keep agar plates in school at?

Answer 22

25 degrees C

Question 23

How did Semmelweiss reduce deaths in Austria in the 1840’s?

Answer 23

Hand washing when moving between patients

Question 24

During WW1 nearly 20% of US soldiers who caught pneumonia ( a bacterial infection) died as a result. During WW11 this figure dropped to less than 1%. Why?

Answer 24

We had penicillin to treat bacterial infections

Question 25

What do we say viruses have done when they change their protein coat?

Answer 25

Mutated

Question 26

What is a pandemic?

Answer 26

A global spread of a disease

Question 27

What do White blood cells do?

Answer 27

Look at the diagram

Question 28

Describe the graph and explain why it takes a week and a half to increase the antibodies after the first injection.

Answer 28

The line shows the antibody level increases a week and a half after the first vaccination, peaking at 4 weeks but the decreases and goes below the immunity level at 6 weeks when the booster is given. It then rises straight away. This is because the white blood cells know which antibody needs to be made straight away. The immunity goes up and this time stays abouve the immunity level.

Question 29

What is a booster?

Answer 29

A follow up injection which you are given if your immunity drops

Question 30

Who is this? Charles Darwin or Ignaz Semmelweiss?

Answer 30

Ignaz Semmelweiss