Edexcel Biology Gcse - Health, Disease and the Development of Medicines Sample Exam Questions and Answers

Antigen

Effectiveness

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

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

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

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

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

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

the bacterium will divide three times each hour and so 3 × 6 = 18 times in total 1 × 218 = 262,144

6.71 × 10^7

1 mark for calculation and 1 mark for units:

area = πr^2

area = 3.14 × 11^2

Area = 379.94 mm^2

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

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)

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

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

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

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

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

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

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