Health, Disease And The Development Of Medicines

Question 1

According to the World Health Organization (WHO) what is the definition off health?

Answer 1

A state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.

Question 2

What are communicable diseases and provide examples?

Answer 2

Can be transferred between individuals through pathogens. This might be through air droplets, oral-route or bodily fluids.
Examples: Flu, common cold

Question 3

What are non communicable diseases and provide examples?

Answer 3

Non communicable – Cannot be transferred between individuals. Usually due to genetics or lifestyle conditions.
Examples: Cardiovascular disease, asthma and diabetes

Question 4

What is a pathogen?

Answer 4

A microorganism that causes diseases.

Question 5

How can pathogens infect plants or animals? (3)

Answer 5

Direct contact (touching contaminated surfaces)
Water (drinking dirty water)
Air (droplet infection such as sneezing and coughing)

Question 6

What are some ways to prevent the spread of pathogens? (4)

Answer 6

Improving hygiene: Hand washing, using disinfectants
Reducing contact with infected individuals
Removing vectors: Using pesticides or insecticides and removing their habitats
Vaccination

Question 7

Describe the lytic pathway of a virus (4)

Answer 7

1. Using host cell machinery, the virus replicates its DNA.
2. Next, these are assembled to form new virus particles.
3. Once the host cell is full of virus particles, it bursts in a process called lysis.
4. The process is then repeated with nearby cells.

Question 8

Describe the lysog.
#enic pathway (3)

Answer 8

1. The viruses uses restriction enzymes to insert its DNA into the host cell DNA or it can insert plasmids into the host cell cytoplasm.
2. The host cell replicates, and the viral DNA is also copied in this process.
3. The lytic cycle begins at this point, starting with the assemble of new viral particles.

Question 9

Describe how a housefly can cause a person to become infected with dysentery

Answer 9

Housefly carries pathogen.
Housefly lands on contaminated faeces/food waste.
Transfers bacteria on food.
The food is then eaten.

Question 10

Explain how the Anopheles mosquito can spread the disease malaria

Answer 10

Mosquito is a vector.
They carry a plasmodium.
It pierces the skin and transfers the plasmodium in the blood.

Question 11

What are STIs and how are they spread?

Answer 11

STIs can be spread through sexual contact, including oral and vaginal sex. They are carried in bodily fluids such as semen and vaginal fluid.

Question 12

Name two STIs and their symptoms

Answer 12

Chlamydia - Bacteria - Often symptomless, but it can include painful urination or pelvic pain. Left untreated it can lead to infertility.
HIV - Virus - Increased susceptibility to other infections, severe illness and death if untreated.

Question 13

How can the spread of STIs can be reduced? (2)

Answer 13

Using barrier methods of contraception or abstaining from sexual activity.

Question 14

What are some plant physical barriers against disease?(4)

Answer 14

1. Thick cellulose cell wall – impermeable to many pathogens
2. Thick waxy cuticle on the surface of the leaf – acts as a barrier to most pathogens
3. Some plants are also covered in a layer of bark (trees) – prevents pathogens from reaching the cells and tissues inside
4. Leaves can often close their stomata to stop pathogens entering the plant

Question 15

What are some plant chemical barriers against disease? (3)

Answer 15

1. Cells of some plants can produce antimicrobial, proteins and enzymes
2. Some plants can release compounds that attract larger insects than the pests, which feed on the pests
3. Often, we can extract antimicrobial compounds from these plants for use in drugs such as antibiotics

Question 16

Why is detecting and identifying diseases in crops important?

Answer 16

It helps prevent the spread of disease across the entire crop.

Question 17

How can diseases be identified in the field? (4)

Answer 17

1. Chalara ash dieback causes malformations and browning of leaves.
2. Tobacco mosaic virus causes discolouration of leaves.
3. Bacterial canker on fruit trees cause loss of leaves, stunted growth and formation of pus-filled lesions on trunk.
4. Aphids can cause serious structural damage to plants.

Question 18

How are diseases identified in the lab?(3)

Answer 18

1. Cuttings are taken from the diseased plant.
2. The virus/bacterium causing the disease is grown on a culture medium/agar plate.
3. The pathogen is tested and identified using a monoclonal antibody testing kit.

Question 19

What are some human physical barriers against disease?(3)

Answer 19

Mucus traps bacteria and other pathogens before they reach the lungs and cause an infection.
Cilia wafts away mucus that has trapped pathogens, to be killed by stomach acid.
Skin provides a physical barrier against pathogens, protecting the tissues and cells beneath it from infection.

Question 20

What are some animal chemical barriers against disease? (3)

Answer 20

Lysozymes, found in white blood cells - Used by white blood cells to kill and digest bacteria.
Hydrochloric acid, found in stomach - Used to kill bacteria in food reaching the stomach – to prevent infection.

Question 21

Describe the primary immune response.

Answer 21

Some lymphocytes detects pathogens/antigens on the pathogen.
A lymphocyte with antibodies that matches the shape of the antigen is activated and produces antibodies.
The antibodies fit onto the antigens and cause them to clump.
The pathogen is then destroyed (often by phagocytes). Some lymphocytes remain and become memory lymphocytes.
During this time, you feel ill.

Question 22

Explain the secondary immune response.

Answer 22

Infection by the same pathogen (antigens).
Memory lymphocytes immediately start to produce antibodies to that pathogen.
Pathogens usually die very quickly and you don’t feel ill.

Question 23

What is herd immunity?

Answer 23

Immunising a large population, and reducing the spread of a pathogen as there is less people to catch the disease.

Question 24

What is vaccination?

Answer 24

The vaccine contains a dead/inactivated form of the pathogen.
This stimulates white blood cells to produce antibodies complementary to the antigens on the pathogen.

Question 25

What are some advantages of vaccination? (2)

Answer 25

1. It has eradicated many diseases so far (e.g small pox) and reduced the occurrence of many (e.g rubella).
2. Epidemics (lost of cases in an area) can be prevented through herd immunity

Question 26

What are some disadvantages of vaccination? (2)

Answer 26

1. They are not always effective in providing immunity.
2. Bad reactions (such as fevers) can occur to response to vaccines.

Question 27

What types of infections can antibiotics treat?

Answer 27

Antibiotics can only be used to treat bacterial infections.

Question 28

Why are bacteria susceptible to antibiotics?

Answer 28

Bacteria are susceptible to antibiotics because antibiotics inhibit cell processes in the bacterium.

Question 29

Explain two ways to grow microorganisms in the lab. (2)

Answer 29

1. In nutrient broth solution – involves making a suspension of bacteria to be grown and mixing with sterile nutrient broth (the culture medium), stoppering the flask with cotton wool to prevent air from contaminating it and shaking regularly to provide oxygen for the growing bacteria.
2. On an agar plate – the agar acts as the culture medium, and the bacteria grown on it forms colonies on the surface.

Question 30

Explain why petri dishes should be sterilised?

Answer 30

If this doesn’t take place, they are likely to be contaminated with other microorganisms.

Question 31

Explain why inoculating loops must be sterilised?

Answer 31

Kills unwanted microorganisms.

Question 32

Explain why the lid of petri dish should be sealed with tape?

Answer 32

Stops airborne microorganisms from contaminating the culture. However, it should not be sealed all the way around as this would result in harmful anaerobic bacteria growing due to no oxygen entering.

Question 33

Explain why the petri dish should be stored upside down?

Answer 33

Prevent condensation from the lid, disrupting growth.

Question 34

Explain why the culture medium should be incubated at 25 degrees?

Answer 34

If incubated at a higher temperature, bacteria could be harmful to humans .At lower temperatures, colonies of such bacteria would not be able to grow.

Question 35

Describe the process of growing a bacterial culture. (2)

Answer 35

1. Take a petri dish with pre-poured agar gel, and sterilise it in an autoclave. Use a inoculating loop (sterilise in a Bunsen burner) to apply the bacteria being tested to the agar. Seal the top of the plate using tape. Incubate the culture at 25 degrees for 3 days.
2. Apply a filter disc soaked in antibiotic solution to the centre of the agar plate and wait for 24 hours or until there is no further change.

Question 36

How do you calculate the effectiveness of the antibiotic? (3)

Answer 36

1. Use a ruler to measure the diameter of the circle taken up by the bacterial culture and record this measurement. Repeat for the diameter of the clear agar jelly in the centre, where the antibiotics has killed the bacteria.
2. Divide both diameters by 2 to get the radius of both these circles. Use the formula πr2 to calculate the area of these circles.
3. Divide the area of the smaller circle by the larger, and multiply by 100. This is the percentage of the bacterial culture that has been destroyed by the antibiotic. The higher the percentage the more effective the antibiotic.

Question 37

Why is drug testing necessary for new drugs?

Answer 37

To ensure that new drugs are safe and effective for use in patients.

Question 38

What are the stages of drug testing? (2)

Answer 38

Pre-clinical testing: Involves using cells, tissues and live animals to assess safety.
Clinical testing: Involves patients and volunteers. Initially, healthy volunteers receive a low dose to ensure safety. Then, patients receive varying doses to determine efficacy, often through randomized controlled trials comparing the drug to a placebo. Results are peer-reviewed for repeatability.

Question 39

How are monoclonal antibodies produced? (4)

Answer 39

1. Scientists obtain mice lymphocytes (a type of white blood cell that make antibodies but cannot divide), which have been stimulated to produce a specific antibody.
2. They are combined with tumour cells to form a cell called a hybridoma.
3. The hybridoma can divide to produce clones of itself, which all produce the same antibody.
4. The antibodies are collected and purified.

Question 40

How is the presence of HCG hormone detected in pregnancy tests?

Answer 40

The first section of the test stick contains mobile antibodies complementary to HCG, which bind to the hormone if urine is present. The urine flows to the second section, where stationary antibodies to the HCG/antibody complexes, resulting in a blue line indicating pregnancy.

Question 41

How are monoclonal antibodies used in lab analysis of blood?

Answer 41

Used to measure and monitor levels of hormones or chemicals in the blood.
The monoclonal antibodies are modified so that they will bind to the molecule you are looking for.
The antibodies are also bound to fluorescent dye. So, if the molecules are in the sample, then the antibodies bind to it and the dye can be observed.
An example is screening donated blood for HIV infections.

Question 42

How are monoclonal antibodies used in cancer treatment?

Answer 42

Producing monoclonal antibodies that bind to the tumour markers in order to stimulate the immune system to attack the cell.
Using monoclonal antibodies to bind t receptor sites on the cell surface membrane of the cancer cells . This means growth-stimulating molecules cannot bind, stopping the cell from dividing.
Using monoclonal antibodies to transport toxic drugs, chemicals or radioactive substances as they can only bind to cancer cells.

Question 43

Describe some advantages of using monoclonal antibodies. (3)

Answer 43

1. They are bind to specific cells meaning healthy cells wont be affected.
2. They can be engineered to treat many different conditions.
3. We are now able to produce hybridoma cells to reduce the chance of triggering an immune response.

Question 44

Describe some disadvantages of using monoclonal antibodies. (3)

Answer 44

1. It is difficult to attach monoclonal antibodies to drugs.
2. They are expensive to develop.
3. As they were produced from mice lymphocytes, they often triggered an immune response when used in humans.

Question 45

What factors can contribute to cardiovascular diseases?

Answer 45

Cardiovascular diseases such as coronary heart disease can be caused by high dietary intake of saturated fat, combined with a sedentary (inactive) lifestyle.

Question 46

What factors can contribute to liver diseases?

Answer 46

Liver diseases are caused by high alcohol intake.

Question 47

What factors can contribute to vitamin and nutritional deficiencies?

Answer 47

Vitamin and nutritional deficiencies are common in anorexic patients, as well as those who cant absorb or sue nutrients properly (coeliac and anaemic individuals).

Question 48

What factors can contribute to cancer?

Answer 48

Several forms of cancer can be caused smoking greatly as it increases the risk of lung cancer, whereas the risk of developing breast cancer is largely due to age and genetics

Question 49

What factors can cause obesity?

Answer 49

Obesity is caused by excess caloric intake and can be heavily influenced by genetics.

Question 50

How is BMI calculated?

Answer 50

BMI = Mass(kg)/Height2 (m2)

Question 51

What is the waist-hip ration used for?

Answer 51

The waist-hip ratio is calculated by dividing waist circumference by hip circumference, used to asses abdominal obesity and overall health risks.

Question 52

What are some treatments for cardiovascular diseases? (3)

Answer 52

Long life medication - There are several medications that will either reduce cholesterol or reduce blood pressure. They will most likely have to take these for the rest of their life.
Surgical procedures - Coronary arteries supply the heart muscle with oxygen and cover the heart. If these are blocked, a coronary heart bypass can be performed. Another method involves using a metal stent to widen arteries that have been narrowed by fat deposits.
Lifestyle changes - Reducing the amount of saturated fat we eat we can reduce the risk of developing fat deposits in the arteries and high cholesterol. Maintaining a healthy BMI can reduce strain on the heart. Taking regular exercise.

Question 53

Devise a plan the scientist could use to test the effectiveness of the new diet
using the 40 obese people. (3)

Answer 53

1. Weigh the 40 obese people.
2. Half follow the new diet half keep their normal diet.
3. After a fixed time period reweigh the 40 people.

Question 54

Explain how the order of amino acids in a protein is determined by the sequence of the gene (4)

Answer 54

1. A single strand of mRNA is transcribed from the gene in the nucleus.
2. mRNA molecule binds to the ribosome.
3. The triplet code from the mRNA is complementary to the tRNA anticodon at the ribosome.
4. tRNA transfers amino acids to the polypeptide chain in a specific order.

Question 55

Describe two ways in which monoclonal antibodies are used in medical diagnosis

Answer 55

1. Pregnancy testing
2. Locating the position of cancers

Question 56

Explain the advantages of treating cancer using monoclonal antibodies.

Answer 56

Antibodies only attach to cancer cells.
Alerts immune system to target cancer cells.