P1-Topic 3-Infection and response 2022

Question 1

What is a communicable disease?

Answer 1

A disease caused by a pathogen which can be passed between animals or plants eg. flu.

Question 2

What is a pathogen?

Answer 2

A disease-causing microorganism e.g.

bacteria.

Question 3

How do bacteria cause disease? 2

Answer 3

Once inside the body, they divide rapidly by binary fission.

They kill cells and produce harmful toxins.

Question 4

How do viruses cause disease? 3

Answer 4

They invade and reproduce inside living
body cells, leading to cell damage

The damage and the destruction of the cells makes the individual feel ill

Question 5

how diseases caused by protists spread in animals and plants. 2

Answer 5

Some are parasitic, meaning they use humans and animals as their hosts
(live on and inside, causing damage)

Question 6

how diseases caused by fungi spread in animals and plants. 2

Answer 6

They can either be single celled or have a body made of hyphae (thread-like
structures)
● They can produce spores which can be spread to other organisms

Question 7

Give three ways in which pathogens can be spread

3

Answer 7

By air - flu, tuberculosis and the common cold are spread by droplet infection.

● By water - fungal spores in water spread plant diseases.

● By direct contact - common in plant diseases and sexually transmitted infections.

Question 8

Give four ways in which the spread of pathogens can be reduced 4

Answer 8

● Hygiene - handwashing, disinfectants, tissues.
● Reducing contact with infected individuals - quarantine.
● Removing vectors - use of pesticides and insecticides, removal of habitats.
● Vaccination

Question 9

Why is it especially important to prevent the spread of viral diseases?

Answer 9

Scientists have not yet developed cures for many viral diseases.

measels, rubella, chicken pox

Question 10

What is measles?How is measles spread?

3

Answer 10

serious viral disease that can cause blindness and brain damage.

main symptoms are a fever and a red skin
rash.

By air - through the inhalation of droplets
from coughs and sneezes

Question 11

What is HIV/AIDS? 3

Answer 11

HIV is a virus which attacks and damages the immune system until it can no longer function properly.

AIDS is the condition resulting from a
long-term HIV infection. There is no cure or vaccine for HIV/AIDS

Direct sexual contact and the exchange
of bodily fluids eg. blood, breastmilk

Question 12

How can the spread of HIV/AIDS be prevented? 5

Answer 12

● Use of condoms
● Screening of blood for transfusions
● Not sharing needles
● Bottle-feeding by HIV-positive mothers
● Use of antiretroviral drugs to prevent the development of AIDS

Question 13

What is tobacco mosaic virus?3

Answer 13

-plant pathogen which causes leaf discolouration when cells are damaged.

Affected areas cannot photosynthesise, reducing the crop yield

no treatment, farmers grow TMV-resistant crop strains to avoid infection

Question 14

How is tobacco mosaic virus spread?2

Answer 14

Contact between infected and healthy plants

Insects may act as vectors which transfer the virus between different plants.

Question 15

What is salmonella?

Answer 15

A type of bacteria found in raw meat, poultry and eggs.

If they enter the body via food
poisoning, they can affect natural gut
bacteria

Question 16

What are the symptoms of salmonella food poisoning? 4

Answer 16

● Fever
● Abdominal cramping
● Vomiting
● Diarrhoea
May be fatal in very young or elderly populations due the
risk of dehydration.

Question 17

How can the spread of salmonella be limited? 3

Answer 17

● Vaccinating animals intended for consumption
● Keep raw meat away from cooked meat
● Disinfect hands and surfaces after contact with raw meat
● Thoroughly cook meat

Question 18

What is gonorrhoea?3

symptoms and treatment

Answer 18

A sexually transmitted bacterial infection caused by unprotected sex with an infected individual.

Early symptoms: yellow/green discharge from genitals and painful urination, although it may be symptomless.

Its spread can be controlled through the use of antibiotics (no longer penicillin as many strains are resistant) and using
condoms

Question 19

What is rose black spot?2

Answer 19

A fungal disease which causes purple or black spots to develop on rose leaves.

It reduces the area of the leaf which is available for photosynthesis and causes leaves to turn yellow and drop prematurely

Question 20

How is the rose black spot fungus spread?

How can the rose black spot fungus be treated? 2

Answer 20

-Fungal spores are spread by the wind
and in water

-● Using fungicides
● Destroying infected leaves

Question 21

What is malaria? and symptoms 3

Answer 21

disease caused by protist pathogens

disease is carried from host to host by
mosquitoes, and the protists enter the human bloodstream when they feed.

Symptoms include fever and shaking, and it may also be fatal in some cases

Question 22

How can the spread of malaria be reduced?

4

Answer 22

● Using insecticides
● Using insect nets to avoid bites
● Prevent mosquito breeding by removing stagnant water
● Antimalarial drugs

Question 23

How does the skin prevent pathogens from entering the body? 4

Answer 23

● Acts as a physical barrier.
● Scab formation after skin is cut/wounded.
● Antimicrobial secretions which can kill pathogens.
● Healthy skin flora compete with pathogens and act as an additional barrier

Question 24

How does the respiratory system prevent pathogens from entering the body?
(nose, trachea and bronchi) 3

Answer 24

● Nose - has hairs and mucus which trap
pathogens.

● Trachea and bronchi - have mucus that traps pathogens. Ciliated cells move mucus to the mouth so it can be swallowed.

Question 25

How does the stomach prevent pathogens infecting the body?

Answer 25

● Secretes hydrochloric acid - kills any pathogens present.

Question 26

how does the immune system use white blood cells to destroy pathogens

Answer 26

• phagocytosis
• antibody production
• antitoxin production

Question 27

How does phagocytosis protect us against disease?

Answer 27

White blood cells (phagocytes) ingest and destroy pathogens so they cannot infect more cells.

Question 28

How does antibody production protect us against disease? 4

Answer 28

White blood cells produce antibodies which are complementary to a specific antigen on a pathogen.

The binding of antibodies to antigens causes pathogens to clump together, making them easier to destroy.

In the case of a second infection, the correct antibodies can be produced rapidly,

preventing the person getting the same disease again

Question 29

How does antitoxin production protect us

against disease?

Answer 29

Antitoxins bind to toxins released by pathogens and neutralise them

Question 30

What is a vaccination?2

Answer 30

Contains a dead or inactivated form of the pathogen which stimulates white blood cells to produce complementary antibodies to the pathogen

In the case of a second infection, memory cells can rapidly produce the correct antibodies and prevent illness

Question 31

What is herd immunity?

Answer 31

If a sufficiently high proportion of a population are immune to a disease (especially through vaccination), the spread of this disease will be limited

Question 32

What are the advantages of vaccinations?3

Answer 32

● They have eradicated many deadly diseases eg. smallpox.
● Many epidemics can be prevented by
vaccinations.
● Herd immunity protects those who cannot have vaccinations

Question 33

What are the disadvantages of vaccinations?2

Answer 33

● Not guaranteed to work - might not protect against multiple strains of a pathogen.
● May be side effects or adverse reactions

Question 34

What are monoclonal antibodies (mAbs)?2

Answer 34

● Antibodies that are clones from one
parent cell
● Specific to one type of antigen

Question 35

Describe how monoclonal antibodies are produced?5

Answer 35

1. Specific antigen injected into an animal (e.g. mouse).
2. B-lymphocytes producing complementary antibodies extracted.
3. B-lymphocytes fuse with myeloma cells to form hybridoma cells - these cells can divide and produce antibody.
4. Hybridoma cells cultured.
5. Monoclonal antibodies collected and purified

Question 36

Outline the uses of monoclonal

antibodies

Answer 36

● Detection of pathogens
● Location of cancer cells and blood clots
● Treatment of cancer
● Used in pregnancy test kits

Question 37

What are myeloma cells?

Answer 37

Type of tumour cell

Question 38

What does a pregnancy test consist of? 3

Answer 38

A stick containing monoclonal antibodies (mAbs) specific to hCG:
● mAbs attached to a blue bead (free to move)
● mAbs fixed to the test stick

Question 39

Describe what happens to the test stick if a woman is pregnant and of not pregnant 4

Answer 39

● hCG in urine binds to mAbs attached to
a blue bead.
● mAbs with hCG diffuse up dipstick.
● mAbs fixed to the stick bind to hCG.
● Blue line forms
-No hCG in urine so a blue line is not
formed.

Question 40

Describe what happens to the test stick if a woman is pregnant and of not pregnant 4

Answer 40

● hCG in urine binds to mAbs attached to a blue bead.
● mAbs with hCG diffuse up dipstick.
● mAbs fixed to the stick bind to hCG.
● Blue line forms
-No hCG in urine so a blue line is not
formed.

Question 41

Describe how monoclonal antibodies can

be used to diagnose cancer4

Answer 41

● mAbs tagged to a radioactive substance.
● mAbs injected into the patient’s bloodstream.
● mAbs bind to ‘tumour markers’ on cancer cells.
● Emitted radiation is detected using a specialised scanner enabling doctors to determine the location of cancer cells

Question 42

Why are cancer treatments that use monoclonal antibodies favoured over traditional treatments?3

Answer 42

● Radiotherapy and chemotherapy target rapidly dividing cells.
● Healthy cells (e.g. hair follicle cells, bone marrow cells) are damaged as a consequence, producing unpleasant side
effects.
● mAbs only target cancer cells, reducing damage to normal cells.

Question 43

How can monoclonal antibodies be used to locate blood clots?3

Answer 43

● mAbs tagged to a radioactive substance.
● mAbs target and bind to specific proteins in blood clots.
● Radiation emitted by mAbs is detected, enabling the location of blood clots to be identified

Question 44

How can monoclonal antibodies be used to target drugs to cancer cells?4

Answer 44

● mAbs attached to an anti-cancer drug.
● mAbs injected into the patient’s bloodstream.
● mAbs bind to ‘tumour markers’ on cancer cells.
● Anti-cancer drug destroys cancer cells.