communicable diseases (required practical)

Question 1

how do you culture microorganisms? (practical)

Answer 1

1. wash your hands thoroughly and disinfect the work surface.
2. sterilise an inoculating loop by holding it in a flame until it is red hot. (then hold it in the air to cool)
3. open the lid of the bacterial culture bottle and hold the neck in a flame.
4. dip the inoculating loop in the flask. (reflame and seal the bottle)
5. lift the petri dish lid slightly, make zigzag streaks gently with the inoculating loop across the agar. (quickly replace the lid)
6. tape the lid down leaving some air gaps.
7. store the petri dish upside down in an incubator at 25°c.
   (flame the inoculating loop)

Question 2

how do you investigate the effects of antibiotics on bacterial growth? (practical)

Answer 2

1. soak similar sized filter paper discs in different types or concentrations of antibiotics and one disc in distilled water.
2. place the discs equidistant across a preprepared agar plate with sterile forceps.
3. tape the lid of the petri dish down leaving some air gaps.
4. incubate the bacteria upside down at 25°c for 48 hours.
5. the disc with the largest zone of inhibition is the most effect antibiotic.

Question 3

how do you calculate the size of the zone of inhibition?

Answer 3

area = π x r²

Question 4

what is a pathogen? (also what are the 4 types)

Answer 4

a microorganism that enters the body can causes disease.
bacteria.
virus.
protozoa.
fungi.

Question 5

what are bacteria and how do they make you ill?

Answer 5

bacteria are very small cells (1/100th of a body cell) that rapidly reproduce in your body.
they make you ill by producing toxins (poison) that damage your cells and tissues.

Question 6

what are viruses and how do they make you ill?

Answer 6

a virus is genetic information inside a shell called a capsid (1/100th of a body cell) that rapidly reproduces in your body.
they live inside you cells and replicate using the cell’s machinery, then they will all burst out.
they make you ill via cell damage.

Question 7

what are protists and how do they make you ill?

Answer 7

protists are single cell eukaryotes.
they make you ill by living in your body and feeding on your tissues. (they are parasites)

Question 8

what are fungi and how do they make you ill?

Answer 8

fungi are single cell or multicell made of hyphae.
they make you ill by growing and penetrating the skin of plants or animals.

Question 9

what are 3 ways pathogens can spread?

Answer 9

water - drinking or bathing in dirty water.
air - carried in air and breathed in.
direct contact - touching contaminated surface.

Question 10

what are 3 viruses?

Answer 10

measles - droplets - red skin rash.
HIV - bodily fluids - initial flu like symptoms - progress to AIDS if untreated.
TMV - effects plants - mosaic pattern - affects growth.

Question 11

what is 1 fungal disease?

Answer 11

rose black spots - purple or black spots on leaves - affects growth - water and wind - treat using fungicide or clipping leaves.

Question 12

what is 1 protist disease?

Answer 12

malaria - mosquito vector when they feed on an infected animal - repeating fever - mosquito net.

Question 13

what are 2 bacterial diseases?

Answer 13

salmonella - fever, stomach cramps, vomit, diarrhoea - contaminated food - poultry vaccination.
gonorrhoea - sexual contact - pain when urinating - thick yellow discharge - antibiotics, barrier.

Question 14

how can the spread of disease be reduced or prevented? (4)

Answer 14

1. hygiene. (prevent spread)
2. destroying vectors. (prevent spread)
3. isolating infected individuals. (prevents passing on)
4. vaccination. (less likely to develop infection)