Exam (elaborations)
Biology Human Disease 2 Questions and Answers 2024
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Biology Human Disease 2
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Biology Human Disease 2The parts of the blood can be separated from each other by spinning the blood in a
centrifuge.
The image below shows the separated parts of a 10 cm3 blood sample.
(a) Calculate the percentage of the blood that is made up of plasma. - answer5. ×
100
55%
(b) Name three chemical substances transported by the plasma. - answer• amino acids
• antibodies
• antitoxins
(c) In this question you will be assessed on using good English, organising information
clearly and using specialist terms where appropriate.
White blood cells are part of the immune system. White blood cells help the body to
defend itself against pathogens.
Describe how pathogens cause infections and describe how the immune system
defends the body against these pathogens. - answer• bacteria and viruses are
pathogens
• they reproduce rapidly inside the body
• bacteria may produce poisons / toxins (that make us feel ill)
• viruses live (and reproduce) inside cells (causing damage).
white blood cells help to defend against pathogens by:
• ingesting pathogens / bacteria / (cells containing) viruses
• to destroy (particular) pathogen / bacteria / viruses
• producing antibodies
• to destroy particular / specific pathogens
• producing antitoxins
• to counteract toxins (released by pathogens)
• this leads to immunity from that pathogen.
Antibiotics can be used to protect our bodies from pathogens.
(a) What is a pathogen? - answermicroorganism / bacteria / virus / fungus that causes
(infectious) disease
Bacteria may become resistant to antibiotics.
How can doctors reduce the number of bacteria that become resistant to antibiotics? -
answerreduce / stop use of (current) antibiotics
(reduce / stop use) for non-serious / mild / viral infections
,(c) Scientists grow microorganisms in industrial conditions at a higher temperature than
is used in school laboratories.
(i) Which temperature would be most suitable for growing bacteria in industrial
conditions?
Draw a ring around the correct answer.
(ii) What is the advantage of using the temperature you gave in part (c)(i) - answer40 °C
• microorganisms grow / reproduce / work / act faster
• results / product acquired sooner
Some infections are caused by bacteria.
(a) The genetic material is arranged differently in the cells of bacteria compared with
animal and plant cells.
Describe two differences. - answer• may have plasmids
• not in a nucleus / no nucleus
(b) Tuberculosis (TB) is an infection caused by bacteria.
The table below shows the number of cases of TB in different regions of southern
England from 2000-2011.
(i) How does the number of cases of TB for London compare with the rest of southern
England? - answerLondon is much higher
more variable / wider range
(ii) Describe the pattern in the data for cases of TB in the South East. - answerincreases
(iii) Describe the pattern in the data for cases of TB in the South West. - answeroverall
slight increase
variable / goes up and down
(c) (i) On the graph paper below:
• plot the number of cases of TB in London
• label both the axes on the graph
• draw a line of best fit. - answerboth axes correctly labelled
x = Year
y = Number of cases
correct points
suitable line of best fit
(ii) Suggest why a student thought the value for 2005 in London was anomalous. -
answerdoesn't fit the pattern / line of best fit
(d) People can be vaccinated against TB.
Suggest how a vaccination programme would reduce the number of people with TB.
Details of how a vaccine works are not required. - answerprovides immunity / protection
(to TB)
prevents TB spreading
, The MMR vaccine is used to protect against measles.
(a) Apart from measles, which two other diseases does the MMR vaccine protect
against? - answermumps
rubella
(b) Read the information.
(i) Calculate the percentage of the children who caught measles in April 2013 who had
not been vaccinated against MMR. - answer80(.0)
(ii) Suggest one advantage to the population as a whole of children having the second
MMR vaccination. - answerless chance of epidemic / pandemic
(c) (i) What does a vaccine contain? - answerdead / inactive pathogens / viruses /
bacteria
(ii) Explain how a vaccination prevents infection. - answerwhite blood cells produce
antibodies
antibodies produced rapidly (on re-infection) or response rapid (on re-infection)
these antibodies kill pathogens / viruses / bacteria
(d) (i) Antibiotics can only be used to treat some infections.
Explain why antibiotics cannot be used to treat measles. - answerantibiotics don't kill
viruses
(because measles) virus / pathogen lives inside cells
(ii) Why do antibiotics become less useful at treating an infection if the antibiotic is
overused? - answer(bacteria / pathogens) develop resistance (to antibiotic)
A student is given a tube containing a liquid nutrient medium. The medium contains one
type of bacterium.
(a) In this question you will be assessed on using good English, organising information
clearly and using specialist terms where appropriate.
The student is told to grow some of the bacteria on agar jelly in a Petri dish.
Describe how the student should prepare an uncontaminated culture of the bacterium in
the Petri dish.
You should explain the reasons for each of the steps you describe. - answerPre-
inoculation
• Petri dish and agar sterilised before use
• to kill unwanted bacteria
• inoculating loop passed through flame / sterile swab
• to sterilise / kill (other) bacteria
Inoculation
• loop/swab used to spread/streak bacterium onto agar
Allow other correct methods, eg bacterial lawns
• lid of Petri dish opened as little as possible
• to prevent microbes from air entering
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