B5 Communicabe Diseases

Question 1

If you are growing a bacterial culture, why must you first heat the nutrient jelly to 120°C before adding the bacteria you want?

Answer 1

To kill any unwanted microorganisms that might also grow.

Question 2

What is the maximum temperature at which bacteria should be incubated in a school laboratory?

Answer 2

25°C

Question 3

If you add some antibiotics to a petri dish, how do you know which antibiotic was most effective at killing the bacteria?

Answer 3

The one with the biggest circle of no bacterial growth will be most effective.

Question 4

In the past doctors used to examine dead bodies and then treat patients without washing their hands.

Why do you think this led to a high patient death rate?

Answer 4

Pathogens (germs) were passed on by the doctors from the dead bodies to the patients.

Question 5

What is an antibiotic, and what does it do?

Answer 5

It is a medicine that kills bacteria (not viruses).

Question 6

MRSA is causing problems in hospitals.

Give one reason why.

Answer 6

MRSA is resistant to antibiotics.

Question 7

It is difficult to kill viruses inside the body because viruses…

a) live inside cells
b) have a protein coat
c) are too small to be detected

Answer 7

a) live inside cells.

Question 8

A vaccine contains an ______ form of the virus.

Answer 8

inactive (or dead)

Question 9

The vaccine stimulates the white blood cells to produce…

Answer 9

antibodies.

Question 10

Is there a link between vaccinations and autism?

Answer 10

No.

Question 11

Organsims that cause disease are called…

Answer 11

pathogens.

Question 12

What is a pandemic?

Answer 12

A disease affecting people in many countries.

Question 13

The swine flu virus is carried by pigs. The bird flu virus is likely to spread much more quickly than the swine flu virus. Suggest one reason why.

Answer 13

Birds fly and there are more birds than pigs.

Question 14

Why will antibiotics not get rid of flu?

Answer 14

Antibiotics only kill bacteria and antibiotics don’t kill viruses.

Question 15

The symptoms of flu include a sore throat and aching muscles.

What would a doctor give to a patient to relieve the symptoms of flu?

Answer 15

Painkillers.

Question 16

It is important that antibiotics are not overused.

Overuse of antibiotics might speed up the development of _____ strains of _____.

Answer 16

Overuse of antibiotics might speed up the development of resistant strains of bacteria.

Question 17

Describe how a student should prepare an uncontaminated culture of a bacterium in a Petri dish.

Answer 17

1. Sterilise petri dish, agar gel and swab before use to kill unwanted bacteria.
2. Use swab to spread bacteria onto agar gel. Only open lid slightly to prevent microbes in the air entering.
3. Seal the dish and lid with tape. Incubate in warm conditions (25°C) to allow bacteria to grow.

Question 18

After adding a drop of disinfectant to a bacterial culture, it is found no bacteria grew around that region. Why?

Answer 18

The disinfectant killed the bacteria.

Question 19

A student tests different disinfectants on a bacterial culture. He concludes the one which causes the largest area with no bacterial growth is the best for use at home.

Why might the student not be correct?

Answer 19

e. g.
- The disinfectant might be harmful to humans.

• The disinfectant might not work on all types of bacteria.
• The disinfectants tested may have had different concentrations so it was not a fair test.