T3 - communicable diseases

Question 1

Define the term communicable disease.

Answer 1

A communicable disease is an illness caused by pathogens that can be spread between individuals within a population.

Question 2

What are pathogens?

Answer 2

Pathogens are microorganisms that cause disease.

Question 3

True or False? Only animals can be affected by pathogens.

Answer 3

False. Plants and animals can be affected by pathogens.

Question 4

Name the different types of pathogen.

Answer 4

Types of pathogen include: bacteria; viruses; fungi; protists.

Question 5

How do bacteria cause damage to the body?

Answer 5

Bacteria cause damage to the body by reproducing rapidly and producing toxins which damage tissues.

Question 6

What are the main ways that pathogens are transmitted?

Answer 6

Pathogens are transmitted through: direct contact; contaminated water; droplets carried in the air; contaminated food.

Question 7

True or False? Cooking food thoroughly is a method to prevent the spread of pathogens.

Answer 7

True. Cooking food thoroughly is a method to prevent the spread of pathogens as pathogens are (usually) killed by high temperatures.

Question 8

Where do viruses live and reproduce?

Answer 8

Viruses live and reproduce inside living cells of a host organism.

Question 9

What is measles?

Answer 9

Measles is a viral infectious disease with symptoms including a fever and a rash. It spreads easily and can be fatal if complications arise.

Question 10

True or False? Young children are not vaccinated against measles.

Answer 10

False. Young children are usually vaccinated against measles.

Question 11

How is measles transmitted between people?

Answer 11

The measles virus is spread by inhalation of droplets (from sneezes and coughs) that contain the virus.

Question 12

How does HIV cause harm?

Answer 12

HIV can damage the immune system, eventually leading to acquired immune deficiency syndrome (AIDS).

Question 13

What are the initial symptoms of HIV infection?

Answer 13

The initial symptoms of HIV infection are flu-like symptoms (runny nose; sore throat; achy limbs/joints).

Question 14

How is HIV transmitted?

Answer 14

HIV is spread by exchange of body fluids, e.g. during sexual contact or when sharing needles. It can also pass across the placenta during pregnancy.

Question 15

Why do plants infected with TMV have reduced growth?

Answer 15

The ‘mosaic’ pattern caused by the virus discolours the leaves; this affects the growth of the plant due to lack of photosynthesis.

Question 16

What is Salmonella?

Answer 16

Salmonella is a bacterial pathogen that causes food poisoning; symptoms include: fever; abdominal cramps; vomiting; diarrhoea.

Question 17

What is the main way that Salmonella infection can spread?

Answer 17

Salmonella enters the human body through ingestion of contaminated food.

Question 18

True or False? Proper food hygiene can help prevent Salmonella.

Answer 18

True. Salmonella bacteria can be found in food prepared in unhygienic conditions. Proper food hygiene can therefore help to prevent Salmonella infection.

Question 19

What is gonorrhoea?

Answer 19

Gonorrhoea is a sexually transmitted disease (STD) caused by a bacterial pathogen. Symptoms include discharge from the sex organs and pain on urinating.

Question 20

How is gonorrhoea transmitted?

Answer 20

Gonorrhoea is transmitted through sexual contact.

Question 21

How can the spread of gonorrhoea be prevented?

Answer 21

Gonorrhoea transmission can be prevented by: treating infected individuals with antibiotics; the use of barrier contraception, e.g. condoms.

Question 22

What is rose black spot?

Answer 22

Rose black spot is a fungal disease of plants where purple or black spots develop on leaves, which often turn yellow and drop early.

Question 23

How does rose black spot affect plants?

Answer 23

Rose black spot affects the growth of the plant as photosynthesis is reduced.

Question 24

How does rose black spot spread?

Answer 24

Rose black spot is spread in the environment by water or wind.

Question 25

How can rose black spot be treated?

Answer 25

Rose black spot can be treated by using fungicides and/or removing and destroying the affected leaves.

Question 26

What type of pathogen causes malaria?

Answer 26

The pathogens that cause malaria are protists.

Question 27

Define the term vector in the context of infectious disease.

Answer 27

A vector is an organism that transfers pathogens from one host to the next.

Question 28

How do malarial protists infect humans?

Answer 28

Malarial protists infect humans when infected mosquitoes bite. The protists pass from the mosquito saliva into the human blood.

Question 29

What are the symptoms of malaria?

Answer 29

Malaria causes recurrent episodes of fever and can be fatal.

Question 30

How is the spread of malaria controlled?

Answer 30

The spread of malaria is controlled by controlling the mosquito vectors, e.g. by: preventing the mosquitoes from breeding; using mosquito nets to avoid being bitten.

Question 31

What is the role of the trachea and bronchi in non-specific immune defence?

Answer 31

The role of the trachea and bronchi are to trap pathogens, dirt, and dust using ciliated epithelial cells and mucus.

Question 32

True or False? Stomach acid is a specific immune defence mechanism.

Answer 32

False. Stomach acid destroys many pathogens so is a non-specific defence mechanism.

Question 33

What is the role of phagocytes in the immune system?

Answer 33

Phagocytes engulf and digest pathogens through phagocytosis.

Question 34

True or False? The body's response to infection involves antigens recognising antibodies.

Answer 34

False. The body's response to infection involves antibodies recognising antigens.

Question 35

What is the role of antibodies in the immune response?

Answer 35

Antibodies attach to antigens on pathogens, binding the pathogens together. This can prevent them from infecting cells, and make it easier for phagocytes to engulf them.

Question 36

What is the role of antitoxins produced by white blood cells?

Answer 36

Antitoxins neutralise toxins released by pathogens, preventing them from causing harm to the body.

Question 37

What is the difference between antigen, antibody, and antitoxin?

Answer 37

The difference between antigen, antibody, and antitoxin is as follows: an antigen is a protein molecule found on the surface of a cell; an antibody is a protein produced by lymphocytes that binds to specific antigens on pathogens; an antitoxin is a protein that neutralises toxins released by pathogens.

Question 38

True or False? Phagocytes release antibodies as part of their immune response.

Answer 38

False. Phagocytes carry out phagocytosis to engulf pathogens; they do not produce antibodies.

Question 39

What is vaccination?

Answer 39

Vaccination introduces dead or inactive pathogens into the body in order to induce immunity.

Question 40

What role do white blood cells play in vaccination?

Answer 40

White blood cells recognise the antigens in a vaccine and produce specific antibodies.

Question 41

How does vaccination lead to long-term immunity?

Answer 41

Vaccination leads to long-term immunity because when someone is infected again by the same pathogen, white blood cells quickly produce the correct antibodies and the symptoms of infection do not arise.

Question 42

True or False? Vaccines increase the likelihood that a pathogen will spread.

Answer 42

False. Vaccinating a large proportion of a population reduces the likelihood that a pathogen will spread; this is because most people in the population will be immune.

Question 43

What are antibiotics?

Answer 43

Antibiotics are medicinal drugs that kill pathogenic bacteria.

Question 44

True or False? Antibiotics can kill viruses.

Answer 44

False. Antibiotics do not destroy viruses, so can only be used to treat bacterial infection.

Question 45

What is antibiotic resistance?

Answer 45

Antibiotic resistance occurs when bacteria survive exposure to antibiotics that would normally kill them or inhibit their growth.

Question 46

What is the role of painkillers in disease treatment?

Answer 46

Painkillers are used to treat the symptoms of disease but do not treat the source of any infection, e.g. ibuprofen can reduce pain and inflammation but does not kill pathogens.

Question 47

Why is it difficult to treat diseases caused by viruses?

Answer 47

It is difficult to treat diseases caused by viruses because viruses infect body cells. This means that destroying viruses without damaging body tissue is challenging.

Question 48

What are some traditional sources of medicinal drugs?

Answer 48

Drugs were traditionally extracted from plants and microorganisms, e.g. digitalis originates from foxgloves; aspirin originates from willow; penicillin comes from Penicillium mould.

Question 49

How are most new drugs developed today?

Answer 49

Most new drugs are synthesised by chemists in the pharmaceutical industry, although the starting point may still be a chemical extracted from a plant.

Question 50

What is preclinical drug testing?

Answer 50

Preclinical drug testing is done in a laboratory using cells, tissues, and live animals.

Question 51

What is the purpose of clinical drug trials?

Answer 51

Clinical drug trials are conducted to test the safety, efficacy, and optimal dosage of new drugs.

Question 52

What is a double-blind drug trial?

Answer 52

In a double-blind trial some patients are given a placebo, and neither the doctor nor the patient knows whether each patient is receiving the placebo or the active drug.

Question 53

Define the term placebo.

Answer 53

A placebo is an inert substance given to some participants in clinical trials instead of a true drug. Its role is to eliminate the effects of the brain and expectations on any results.

Question 54

What is the purpose of testing new drugs on animals?

Answer 54

The purpose of testing new drugs on animals is to see the effect of medicines on a whole organism.

Question 55

How are clinical trials conducted?

Answer 55

Clinical trials are conducted as follows: very low doses of the drug are given to healthy volunteers to test safety; patients with relevant medical conditions take part in the trial, often using a double-blind study, to test efficacy and find the lowest effective dose.