health, disease and the development of medicines sample exam questions and answers Flashcards
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Monoclonal antibodies are used in pregnancy test sticks. What do antibodies bind to? [1 mark]
Antigen
For drugs, what does efficacy mean? [1 mark]
Effectiveness
Cancer is a non-communicable disease. Explain how smoking can affect the development of cancer. Define risk factors in your answer. [4 marks]
Answer (four from):
- risk factors are things that increase a person’s chance of developing a disease
- they can be part of a person’s lifestyle
- they can be substances in a person’s body or their environment
- smoking is a risk factor for lung cancer
- tar in cigarettes is a carcinogen
Describe the difference between HIV and AIDS? [2 marks]
Answer (two from):
- HIV stands for human immunodeficiency virus
- initially only causes mild flu-like symptoms
- AIDS stands for acquired immune deficiency syndrome
- AIDS could develop months or years after infection the virus becomes active and starts to attack the patient’s immune system
Describe the differences between phagocytes and lymphocytes. [4 marks]
Answer (four from):
- phagocytes surround any pathogens in your blood and engulf them
- enzymes inside the phagocytes then breakdown the pathogen
- lymphocytes recognise proteins on the surface of pathogens called antigens
- they then produce antibodies which make pathogens stick together
- lymphocytes also produce antitoxins to neutralise the effects of toxins produced by pathogens
Describe the life cycle of a virus. [4 marks]
Answer (four from):
- they can often survive outside a host for long periods of time
- they then infect a suitable host cell
- they replicate themselves thousands of times
- they copy their genetic material (DNA or RNA) and protein coats
- this often causes the host cell to burst
- other cells can then be infected
Describe the differences between the lytic and lysogenic pathways? [4 marks]
- the lytic pathway occurs when a virus infects a cell and immediately replicates causing the cell the burst
- the lysogenic pathway occurs when a virus infects a cell but does not immediately replicate so the cell does not burst
- the DNA of the virus is incorporated into the host of left in the cytoplasm
- replication and cell lysis will occur at a later time
Describe how monoclonal antibodies are used to diagnose medical conditions. [4 marks]
- monoclonal antibodies are designed to bind to antigens
- monoclonal antibodies specific to the antigens found in the urine of pregnant women used to detect pregnancies
- monoclonal antibodies specific to the antigens on the surface of cancer cells used to detect tumours
- monoclonal antibodies used to locate blood clots
A single bacterium divides every 20 minutes by binary fission. Estimate how many bacteria would be present after 6 hours? [2 marks]
the bacterium will divide three times each hour and so 3 × 6 = 18 times in total
1 × 218 = 262,144
Write 67108864 in standard form to two decimal places. [1 mark]
6.71 × 10^7
The diameter of a bacterial colony on an agar plate is 2 mm. Calculate the area of the colony to two decimal places. [2 marks]
1 mark for calculation and 1 mark for units:
area = πr^2 area = 3.14 × 11^2 Area = 379.94 mm^2
Describe a method to investigate the growth of bacteria in the presence of plant extracts. [4 marks]
Answer (four from):
- soak identically sized disks of filter paper in different plant extracts
- soak one disk in water to act as a control
- place each disk on an agar plate covered with a bacterial colony
- incubate for 24 hours
- measure the area without bacterial growth around the disks
- compare these areas of clearing with the control
Two students are investigating the effects of antiseptics on the growth of bacteria.
State the safety precautions that they should take. [2 marks]
Answer (two from):
- wear safety googles
- tie their hair back if it is long
- work standing up
- wash hands after the experiment is finished
- use aseptic technique (examples of aseptic techniques can be used for additional marks)
Describe two examples of aseptic technique. [2 marks]
Answer (two from):
- killing all microorganisms on equipment such as inoculating loops by flaming them in a Bunsen burner or dipping them in alcohol
- keeping all lids on equipment when not in use
- wearing gloves, eye goggles, lab coats or other protective equipment
Describe and explain how we can prevent the spread of disease. [6 marks]
Possible content to be included:
- water can be sterilised by chemicals or UV light to kill pathogens
- cooking foods thoroughly and preparing them in hygienic conditions kills pathogens
- washing surfaces with disinfectants kills pathogens
- vaccinations introduce a small or weakened version of a pathogen into your body so your immune system learns how to defend itself
- using barrier contraception like condoms stops the transfer of bodily fluids and so sexually transmitted diseases
- additional marks for correct disease and prevention strategy
Describe the ways in which pathogens can be transmitted. Give examples in your answer. [6 marks]
- direct contact which can be sexual or non-sexual
- dirty water can transmit many diseases such as the cholera bacterium
- when a person who is infected by the common cold sneezes they can spray thousands of tiny droplets containing virus particles to infect others
- undercooked or reheated food can cause diseases like Escherichia coli which is a cause of food poisoning
- via another animal called a vector
- additional marks for correct pathogens and disease
Describe the process of making monoclonal antibodies. [6 marks]
- an antigen is injected into a mouse
- the mouse naturally produces lymphocytes
- these produce antibodies specific to the antigen
- spleen cells containing lymphocytes are removed during a small operation
- the spleen cells are fused with cancerous white blood cells called myeloma cells
- these form hybridoma cells called which divide indefinitely
- they produce millions of monoclonal antibodies specific to the original antigen
Doctors are now prescribing fewer antibiotics to reduce the evolution of antibiotic resistant bacteria. Describe the process of evolution of antibiotic bacteria. [5 marks]
Answer (five from):
- in every population there is variation, so some bacteria are resistant whilst others aren’t
- the individuals (in this example, the bacteria) with the most advantageous characteristics are more likely to survive and reproduce
- so those that have the gene for resistance have an advantage
- this is survival of the fittest
- because of inheritance, the offspring of those with the advantageous characteristic are more likely to have it
- this process is repeated over many generations until a new species is produced
Describe the effects of specific virus infections of a plant and an animal. Give the names of the viruses in your answer. [5 marks]
Answer part 1 - plant (maximum three from):
- the tobacco mosaic virus infects tobacco and other closely related species
- it infects the chloroplasts of plant leaves
- it changes their colour from green to yellow or white in a mosaic pattern
- it can also make leaves crinkled or curled up
- This reduces the plant’s ability to photosynthesise, which reduces the crop yield of farmers
Answer part 2 - animal (maximum three from):
- HIV stands for human immunodeficiency virus
- it is transmitted by body fluids, often during unprotected sex but also through cuts and injecting drugs using dirty needles
- immediately after infection, infected people often suffer mild flu-like symptoms
- AIDS stands for acquired immune deficiency syndrome
- months or years after infection the HIV virus becomes active and HIV turns into AIDS
- it starts to attack the patient’s immune system
Antibodies are produced by white blood cells to bind with antigens on the surface of pathogens. Scientists have designed monoclonal antibodies for various uses. Describe some of these uses. [5 marks]
Answer (five from):
- HCG hormone is present in the urine of pregnant women
- monoclonal antibodies that bind with HCG are present on the ends of pregnancy test sticks
- when pregnant women urinate on these sticks that antibodies bind with the antigen in the hormone and indicate pregnancy
- monoclonal antibodies can also bind with antigens on cancer to diagnose the presence of tumours
- they can also take drugs that have been attached to them to tumours to treat them
- they can also help your immune system attack cancers
- they can also bind to and diagnose HIV/AIDS, herpes and chlamydia
