1.
State what is meant by a pathogen.
[1 mark]
- a microorganism that causes disease
JD SCIENCE
Disease, defence and treatment
Indicative marking points. Award marks for equivalent scientific or mathematical wording. Do not issue this sheet with the student worksheet.
2.
State what is meant by a virus.
[1 mark]
- a pathogen that reproduces inside cells
3.
State what is meant by a bacterium.
[1 mark]
- a prokaryotic pathogen that can produce toxins
4.
State what is meant by a vaccine.
[1 mark]
- dead or inactive pathogen / antigen introduced to the body
5.
State what is meant by herd immunity.
[1 mark]
- a large proportion of the population is immune so the pathogen cannot spread easily
6.
State what is meant by an antibiotic.
[1 mark]
- a drug that kills bacteria or stops them growing
7.
State what is meant by a white blood cell.
[1 mark]
- a cell that defends the body
8.
State what is meant by phagocytosis.
[1 mark]
- engulfing and digesting a pathogen
9.
State what is meant by the first line of defence.
[1 mark]
- barriers that stop pathogens entering
10.
State what is meant by a clinical trial.
[1 mark]
- testing a drug for safety and effectiveness
11.
Owain is asked about a pathogen in a WJEC Biology paper.
(a) [2 marks]
- bacteria, viruses, fungi, protists
(b) [3 marks]
- why viruses are not treated with antibiotics
12.
Owain is asked about a virus in a WJEC Biology paper.
(a) [2 marks]
- much smaller than bacteria
(b) [3 marks]
- why viral diseases cause cell damage
13.
Owain is asked about a bacterium in a WJEC Biology paper.
(a) [2 marks]
- reproduces by binary fission
(b) [3 marks]
- why some bacterial diseases make you feel ill
14.
Owain is asked about a vaccine in a WJEC Biology paper.
(a) [2 marks]
- stimulates white blood cells to make antibodies and memory cells
(b) [3 marks]
- why a second exposure gives a faster response
15.
Owain is asked about herd immunity in a WJEC Biology paper.
(a) [2 marks]
- protects people who cannot be vaccinated
(b) [3 marks]
- why vaccination programmes aim for high uptake
16.
Owain is asked about an antibiotic in a WJEC Biology paper.
(a) [2 marks]
- does not work on viruses
(b) [3 marks]
- why overuse of antibiotics is a problem
17.
A bacterium divides every 20 minutes. Starting from 1 cell, how many after 2 hours?
[3 marks]
- 6 divisions
- Final answer: 64
18.
A vaccine trial has 200 people. 6 have a serious side effect. Calculate the percentage.
[3 marks]
- 6/200 × 100
- Final answer: 3%
19.
Antibody concentration rises from 2 units to 50 units. Calculate the percentage increase.
[3 marks]
- 48/2 × 100
- Final answer: 2400%
20.
A Petri dish colony count is 120 in 0.1 cm³. Estimate colonies in 5 cm³.
[3 marks]
- ×50
- Final answer: 6000
21.
An antibiotic zone of inhibition has diameter 26 mm. Calculate the area (π=3.14).
[3 marks]
- πr²
- Final answer: 530.7 mm²
22.
A pathogen generation time is 30 minutes. How many generations in 5 hours?
[3 marks]
- 300/30
- Final answer: 10
23.
Owain carries out growing bacteria on agar using aseptic technique. This is a typical WJEC required-practical style question.
(a) [2 marks]
- Independent: antibiotic type / disinfectant concentration
- Dependent: zone of inhibition / colony number
(b) [2 marks]
- same incubation temperature and time
- so the test is fair / only one variable is changed
(c) [2 marks]
- contamination from unsterile loops
24.
Owain carries out testing the effectiveness of disinfectants. This is a typical WJEC required-practical style question.
(a) [2 marks]
- Independent: disinfectant
- Dependent: zone of inhibition
(b) [2 marks]
- same volume on each disc
- so the test is fair / only one variable is changed
(c) [2 marks]
- discs not equally soaked
25.
Owain carries out investigating the effect of antibiotics on bacterial growth. This is a typical WJEC required-practical style question.
(a) [2 marks]
- Independent: antibiotic
- Dependent: clear zone diameter
(b) [2 marks]
- same bacterial lawn
- so the test is fair / only one variable is changed
(c) [2 marks]
- measuring diameter inaccurately
26.
Owain carries out handwashing comparison with agar plates. This is a typical WJEC required-practical style question.
(a) [2 marks]
- Independent: washing method
- Dependent: number of colonies
(b) [2 marks]
- same incubation
- so the test is fair / only one variable is changed
(c) [2 marks]
- unequal contact time with the agar
27.
Compare antibiotics with painkillers.
[4 marks]
- antibiotics kill bacteria
- painkillers treat symptoms only
28.
Compare active immunity with passive immunity.
[4 marks]
- active: memory cells, long-term
- passive: antibodies given, short-term
29.
Compare bacteria with viruses.
[4 marks]
- bacteria are cells and can be killed by antibiotics
- viruses are not cells and need living hosts
30.
Compare preclinical testing with clinical testing.
[4 marks]
- preclinical: cells and animals
- clinical: human volunteers and patients
31.
Apply your knowledge of a white blood cell to this situation: complementary shape to the antigen
[3 marks]
- complementary shape to the antigen
32.
Apply your knowledge of phagocytosis to this situation: works against many pathogens
[3 marks]
- works against many pathogens