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GCSE Biology > B3 - Infection & Response > Flashcards

B3 - Infection & Response Flashcards

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1
Q

What is meant by communicable disease?

A

Can be spread from person to person eg measles.

Spread by pathogens such as bacteria or viruses

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2
Q

What is meant by non-communicable disease?

A

Cannot be passed from person to person eg coronary heart disease

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3
Q

Health is defined as…

A

The state of physical & mental well-being.

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4
Q

Causes of ill health:

A

• Communicable & non-communicable diseases.
• It can also be caused by poor diet, high levels of stress & other life-situations eg working with harmful chemicals.

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5
Q

Define Pathogen

A

Microorganisms that cause infectious disease.

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6
Q

Describe how bacteria cause illness

A

• Once inside the human body, bacteria reproduce very rapidly.

• Bacteria can then release toxins which damage tissues & make us feel ill.

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7
Q

Describe how viruses cause illness

A

• Virus invades the host cell

• Virus now reproduces inside the host cell

• This damages the cell, and when the virus leaves the cell it can cause the cell to burst open & die.

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8
Q

How do pathogens spread?

A

• In the air e.g. in water droplets

• Directly in water

• Direct contact

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9
Q

How to reduce the spread of pathogens

A

• Washing hands before eating

• Providing people with clean drinking water

• Using a condom during sex

• Isolating patients with infectious disease

• Vaccinations

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10
Q

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

A

Scientists have not yet developed cures for many viral diseases

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11
Q

What is measles?

A

A serious viral disease that can cause blindness & brain damage.

The main symptoms are fever and red skin rash.

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12
Q

How is measles spread?

A

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

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13
Q

What is HIV/AIDS

A

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

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

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14
Q

How is HIV spread?

A

Direct sexual contact & the exchange of bodily fluids eg. Blood, breast milk.

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15
Q

How can the spread of HIV/AIDS be prevented?

A

• 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

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16
Q

What is tobacco mosaic virus?

A

A plant pathogen which causes leaf discolouration when cells are damaged. Affected areas cannot photosynthesise, reducing the crop yield.

As there is no treatment, farmers grow TMV-resistant crop strains to avoid infection.

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17
Q

How is tobacco mosaic virus spread?

A

Contact between infected & healthy plants.
Insects may act as vectors which transfer the virus between different plants.

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18
Q

What is Salmonella?

A

A type of bacteria found in raw meat, poultry & eggs.
If they enter the body via food poisoning, they can affect natural gut bacteria.

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19
Q

What are the symptoms of salmonella food poisoning?

A

• Fever
• Abdominal cramping
• Vomiting
• Diarrhoea

May be fatal in very young or elderly populations due to risk of dehydration.

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20
Q

How can the spread of salmonella be limited?

A

• Vaccinationg animals intended for consumption.
• keep raw meat away from cooked meat.
• Disinfect hands & surfaces after contact with raw meat.
• Thoroughly cook meat.

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21
Q

What is gonorrhoea?

How can its spread be controlled?

A

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

Its spread can be controlled by the use of antibiotics using condoms.

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22
Q

Symptoms of gonorrhoea are…

A

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

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23
Q

What is rose black spot?

A

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

It reduces the area of the leaf available for photosynthesis & causes leaves to turn yellow & drop prematurely.

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24
Q

How is the rose black spot fungus spread?

A

Fungal spores are spread by the wind & in the water.

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25
How can rose black spot fungus be treated?
• Using fungicides • Destroying infected leaves
26
What is malaria?
A disease caused by protist pathogens. Disease is carried from host to host by mosquitoes, & the protists enter the him bloodstream when they feed.
27
Symptoms of malaria are…
Fever & shaking, and may also be fatal in some cases.
28
How can the spread of malaria be reduced?
• Insecticides • Mosquito nets • Prevent mosquito breeding by removing stagnant water • Antimalarial drugs
29
How does the skin prevent pathogens from entering the body?
• Acts as a physical barrier • Scab formation after skin is cut/wounded • Antimicrobial secretions which can kill pathogens. • Healthy skib flora compete with pathogens & acts as an additional barrier.
30
How does the respiratory system prevent pathogens from entering the body?
• Nose - hairs & mucus trap pathogens • Trachea & bronchi - mucus that traps pathogens. Ciliated cells move mucus to the mouth so it can be swallowed
31
How does the stomach prevent pathogens infecting the body?
• Secretes hydrochloric acid - kills any pathogens present.
32
How does phagocytosis protect us against disease?
White blood cells (phagocytes) engulf & destroy so they cannot infect more cells.
33
How does antibody production protect us against disease?
WBCs produce antibodies which are specific to the antigen on a pathogen. The binding of antibodies to antigens causes pathogens to clump together, making them easier to destroy. When infected again, the correct antibodies can be produced rapidly, preventing the person getting the same disease again.
34
How does antitoxin production protect us against disease?
Antitoxins bind to toxins released by pathogens and neutralise them.
35
What is a vaccination?
Contains a dead or inactive form of the virus which stimulates WBCs to produce complementary antibodies to the pathogen. In the case of a second infection, memory cells can rapidly produce the correct antibodies & prevent illness.
36
What is herd immunity?
If a sufficiently high proportion of a population are immune to a disease (especially through vaccination), the spread of this disease will be limited.
37
Advantages of vaccinations:
• Eradicated many deadly diseases eg smallpox • Many epidemics can be prevented by vaccinations • Herd immunity protects those who cannot have vaccinations.
38
Disadvantages of vaccinations:
• Not guaranteed to work - might not protect against multiple strains of a pathogen. • May be side effects or adverse reactions.
39
What drugs are used to cure some bacterial diseases?
Antibiotics - they can kill bacterial pathogens inside the body.
40
How do antibiotics work?
Kill bacterial pathogens inside the body but not human cells. Whilst some antibiotics kill a wide range of bacteria, it is important that the right antibiotic is used for specific bacteria.
41
Why can antibiotics bjt be used to treat viral diseases?
Antibiotics have no effect on viral pathogens as they live inside the hosts cells. Therefore, it is difficult to design drugs that would kill the virus and not destroy human cells at the same time.
42
What is antibiotic resistance?
Mutations lead to individual bacterial being resistant to an antibiotic. These bacteria survive and reproduce, leading to a greater proportion of antibiotic-resistant bacteria. This is concerning as some types of bacteria are becoming resistant to all known antibiotics, so the diseases that they cause cannot be cured.
43
How can we prevent antibiotic resistance?
• Avoud overuse & unnecessary use of antibiotics eg use for viral infection. • Finish antibiotic courses - to ensure all bacteria is killed
44
What effect do painkillers have on infectious diseases?
Can only treat the symptoms but do not kill pathogens.
45
What plant is the heart drug digitalis extracted from?
Foxgloves
46
What painkiller originates from a compound found in willow bark?
Aspirin
47
What antibiotic was discovered by Alexander Fleming from a type of mould?
Penicillin
48
What are the four qualities of a good medicine?
• Effective • Safe • Stable • Able to be taken in & removed easily
49
What 3 main factors are tested for when developing new drugs?
• Toxicity • Efficacy • Dose
50
How is preclinical testing carried out?
In a laboratory- uses cells, tissues & live animals
51
How is clinical testing carried out?
Use’s healthy volunteers and patients. Firstly, drug is tested at a low dose on healthy people - then tested on patients and on a larger scale to find the optimum dose. Often, one group receive a placebo and the other group receive the actual drug, in order to assess its efficacy.
52
What is the difference between a single-blind & a double-blind trial?
Single-blind trial: Only the doctor knows whether the patient receives the drug or the placebo. Double blind trial: Neither the patient nor the doctor knows. Double-blind trials help remove bias on the part of the doctor.
53
What is a peer review?
Where the results of drug trials are checked over by scientists knowledgeable in this field.
54
What are monoclonal antibodies?
• Antibodies that are clones from one parent cell • Specific to one type of antigen
55
Describe how monoclonal antibodies are produced
1. Specific antigen injected into an animal 2. B-lymphocytes producing complementary antibodies extracted 3. B-lymphocytes fuses with myeloma cells to form hybridoma cells - these cells can divide and produce antibodies 4. Hybridoma cells cultured. 5. Monoclonal antibodies collected & purified.
56
Outline the uses of monoclonal antibodies
• Detection of pathogens • Location of cancer cells & blood clots • Treatment of cancer • Used in pregnancy test kits
57
What are myeloma cells?
Type of tumour cell
58
What do pregnancy kits test for?
hCG in urine
59
What does a pregnancy test consist of?
A stick containing monoclonal antibodies (mAbs) specific to hCG: • mAbs attached to a blue bead (free to move) • mAbs fixed to the test stick
60
Describe what happens to the test stick if a woman is pregnant
• hCG in urine binds to mAbs attached to a blue bead • mAbs with hCG diffuse up dipstick • mAbs fixed to the stuck bind to hCG • Blue line forms
61
Describe what happens to the test stick if a woman is not pregnant
No hCG in urine so a blue line is not formed
62
What is the advantage of using monoclonal antibodies to test for pathogens?
• Specific to one particular antigen • Very accurate • Quick results
63
Why can monoclonal antibodies be used to target cancer cells?
• Cancer cells have specific antigens called ‘tumour markers’ on their membranes. • mAbs are specific to one type of antigen so can be targeted to ‘tumour markers’ without damaging other cells.
64
Describe how monoclonal antibodies can be used to diagnose cancer
• mAbs tagged to a radioactive substance • mAbs injected into the patients 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.
65
How can monoclonal antibodies be used to target drugs to cancer cells?
• mAbs attached to an anti-cancer drug • mAbs injected into the patients bloodstream • mAbs bind to ‘tumour markers’ on cancer cells • Anti-cancer drug destroys cancer cells
66
Why are cancer treatments that use monoclonal antibodies favoured over traditional treatments?
• Radiotherapy & chemotherapy target rapidly dividing cells. • Healthy cells are damaged as a consequence, producing unpleasant side effects. • mAbs only target cancer cells, reducing damage to normal cells.
67
How can monoclonal antibodies be used to locate blood clots?
• 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
68
How do aphids cause damage to plants?
They use sharp mouthparts to extract sap from the phloem, weakening the plant. They are also vectors who can transfer pathogens from diseased plants to healthy plants.
69
How can we reduce the number of aphids?
• Chemical pesticides • Biological pest control - using ladybirds
70
Why do plants need a hood supply of nitrate ions?
Nitrate ions required to convert sugars into proteins which are required for the plant to grow. As a result, the growth of the plant will be stunted if there is not an adequate supply of nitrates.
71
Why do plants need a good supply of magnesium ions?
Magnesium ions required to synthesise chlorophyll, which absorbs light energy during photosynthesis. As a result, the leaves cannot photosynthesise properly and they turn yellow (chlorosis).
72
What are the symptoms of disease in plants?
• Stunted growth (lack of nitrate ions) • Spotted leaves (eg. Rose black spot fungus) • Decay • Growths • Malformation of stems/leaves • Discolouration • Presence of pests
73
What are 3 ways in which plant disease can be identified?
• Reference to a gardening website or manual • Laboratory testing • Monoclonal antibody test kits
74
Give examples of physical defence responses used by plants?
• Cellulose cell walls • Tough waxy cuticle on leaves • Outside layer on stems/bark on trees • Leaf fall
75
Give examples of chemical defence responses used by plants
• Antibacterial chemicals • Poisons
76
Give examples of mechanical defence responses used by plants used by plants
• Thorns and hairs to deter animals • Leaves that droop/curl on contact • Mimicry to trick animals

GCSE Biology (5 decks)

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