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Biology AQA > B3 Infection and Response > Flashcards

B3 Infection and Response Flashcards

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1
Q

What is a communicable disease?

A

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

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2
Q

What is a pathogen?

A

A disease-causing microorganism e.g. bacteria.

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3
Q

How do bacteria cause disease?

A

Once inside the body, they divide rapidly by binary fission. They kill cells and produce harmful toxins.

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4
Q

How do viruses cause disease?

A

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

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5
Q

Give three ways in which pathogens can be spread

A
  • 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.
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6
Q

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

A
  • Hygiene - handwashing, disinfectants, tissues.
  • Reducing contact with infected individuals - quarantine.
  • Removingvectors-useofpesticidesand
    insecticides, removal of habitats.
  • Vaccination.
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7
Q

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

A

Scientists have not yet developed cures for many viral diseases.

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8
Q

What is measles?

A

Measles is a serious viral disease that can cause blindness and brain damage. The main symptoms are a fever and a red skin rash.

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9
Q

How is measles spread?

A

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

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10
Q

What is HIV/AIDS?

A

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

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11
Q

How is HIV spread?

A

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

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12
Q

How can the spread of HIV/AIDS be prevented?

A
  • 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
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12
Q

How is tobacco mosaic virus spread?

A

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

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13
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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14
Q

What is salmonella?

A

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

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15
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 the risk of dehydration.

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16
Q

How can the spread of salmonella be limited?

A
  • Vaccinating animals intended for consumption
  • Keep raw meat away from cooked meat
  • Disinfect hands and surfaces after contact with raw meat
  • Thoroughly cook meat
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17
Q

What is gonorrhoea?

A

A sexually transmitted bacterial infection caused by unprotected sex with an infected individual. Early symptoms include yellow/green discharge from genitals and painful urination, although ti may be symptomless.

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

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18
Q

What is rose black spot?

A

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.

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19
Q

How can the rose black spot fungus be treated?

A
  • Using fungicides
  • Destroying infected leaves
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20
Q

How is the rose black spot fungus spread?

A

Fungal spores are spread by the wind and in water.

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20
Q

What is malaria?

A

Malaria is a disease caused by protist pathogens. The 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 ti may also be fatal in some cases.

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21
Q

How can the spread of malaria be reduced?

A
  • Using insecticides
  • Using insect nets ot avoid bites
  • Prevent mosquito breeding by removing stagnant water
  • Antimalarial drugs
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22
Q

How does the respiratory system prevent pathogens from entering the body?

A
  • 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.
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22
Q

How does the skin prevent pathogens from entering the body?

A
  • 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.
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23
Q

How does the stomach prevent pathogens infecting the body?

A
  • Secretes hydrochloric acid - kils any pathogens present.
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24
Q

How does phagocytosis protect us against disease?

A

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

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25
Q

How does antibody production protect us against disease?

A

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.

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26
Q

How does antitoxin production protect us against disease?

A

Antitoxins bind to toxins released by pathogens and neutralise them.

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27
Q

What is a vaccination?

A

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.

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28
Q

What is herd immunity?

A

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

29
Q

What are the advantages of vaccinations?

A
  • They have eradicated many deadly diseases e.g. smallpox.
  • Many epidemics can be prevented by vaccinations.
  • Herd immunity protects those who cannot have vaccinations.
30
Q

What are the disadvantages of vaccinations?

A
  • Not guaranteed to work - might not protect against multiple strains of a pathogen.
  • May be side effects or adverse reactions.
31
Q

How do antibiotics work?

A

Antibiotics e.g. penicillin kill bacterial pathogens inside the body, but do not kill human cells.

Whilst some antibiotics kill a wide range of bacteria, it is important that the right antibiotic is used for specific bacteria.

31
Q

What drugs are used to cure some bacterial diseases?

A

Antibiotics - they can kill bacterial pathogens inside the body.

32
Q

Why can antibiotics not be used to treat viral diseases?

A

Antibiotics have no effect on viral pathogens as they live inside the host’s (human) cells.

Therefore, it is difficult to design drugs that would kill the virus and
not destroy human cells at the same time.

33
Q

What is antibiotic resistance?

A

Antibiotic resistance occurs when mutations lead to individual bacteria being resistant to an antibiotic.

These bacteria are able to survive, reproduce and pass on their alleles, 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.

34
Q

How can we prevent antibiotic resistance?

A
  • Avoid overuse and unnecessary use of antibiotics
    • e.g. antibiotics are often used for viral infections.
  • Finish antibiotic courses - to ensure all bacteria is
    killed.
35
Q

What effect do painkillers have on infectious diseases?

A

Painkillers can only treat the symptoms but do not kill pathogens.

36
Q

What painkiller originates from a compound found in willow bark?

A

Aspirin

37
Q

What plant is the heart drug digitalis extracted from?

A

Foxgloves

38
Q

What antibiotic was discovered by Alexander Fleming from a type of mould?

A

Penicillin

39
Q

What are the four qualities of a good medicine?

A
  • Effective
  • Safe
  • Stable
  • Able to be taken in and removed easily
40
Q

What three main factors are tested for when developing new drugs?

A
  • Toxicity
  • Efficacy
  • Dose
41
Q

How is preclinical testing carried out?

A

In a laboratory - uses cells, tissues and live animals

42
Q

How is clinical testing carried out?

A

Uses healthy volunteers and patients. Firstly, the 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 (not the test drug) and the other group receive the actual drug, in order to assess its efficacy.

43
Q

What is the difference between a single-blind and a double-blind trial?

A

In a single-blind trial, only the doctor knows whether the patient is receiving the drug or the placebo.

In a double-blind trial, neither the patient nor the doctor knows. Double-blind trials help remove bias on the part of the doctor.

44
Q

What is a peer review?

A

Where the results of drug trials are checked over by scientists knowledgeable in this field.

45
Q

How do aphids cause damage to plants?

A

They use their sharp mouthparts to extract sap from the plant phloem, weakening the plant.

They are also vectors who can transfer pathogens from diseased plants to healthy plants.

46
Q

How can we reduce the number of aphids?

A
  • Chemical pesticides
  • Biological pest control - using ladybirds
47
Q

Why do plants need a good supply of nitrate ions?

A

Nitrate ions are 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 fi there is not an adequate supply of nitrates.

48
Q

Why do plants need a good supply of magnesium ions?

A

Magnesium ions are required to synthesise chlorophyll, which absorbs light energy during photosynthesis.

As a result, the leaves cannot photosynthesise properly and they turn yellow (chlorosis).

49
Q

What are the symptoms of disease in plants?

A
  • Stunted growth (lack of nitrate ions)
  • Spotted leaves (eg. rose black spot fungus)
  • Decay/rotting
  • Growths
  • Malformation of stems/leaves
  • Discolouration
  • Presence of pests
50
Q

What are three ways in which plant disease can be identified?

A
  • Reference to a gardening website or manual
  • Laboratory testing
  • Monoclonal antibody test kits
51
Q

Give examples of physical defence responses used by plants

A
  • Cellulose cell walls
  • Tough waxy cuticle on leaves
  • Outside layer on stems/bark no trees
  • Leaf fall
52
Q

Give examples of chemical defence responses used by plants

A
  • Antibacterial chemicals
  • Poisons
53
Q

Antibiotics:

A

Medicines that help to cure bacterial disease by killing infective bacteria inside the body.

53
Q

Give examples of mechanical defence responses used by plants

A
  • Thorns and hairs to deter animals
  • Leaves that droop/curl on contact
  • Mimicry to trick animals
54
Q

Clinical drug testing:

A

Drug testing done on healthy human volunteers and patients.

55
Q

Communicable disease:

A

A disease that can be spread between individuals either directly or indirectly.

56
Q

Double blind trial:

A

A study performed where neither the researcher or patient know whether the patient is taking the drug or a placebo.

57
Q

Gonorrhoea:

A

A sexually transmitted disease (STD) caused by a bacterium with symptoms of a thick yellow or green discharge from the vagina or penis and pain on urinating.

58
Q

Human Immunodeficiency Virus (HIV):

A

An infectious virus that weakens the immune system and can lead to AIDS (acquired immunodeficiency syndrome).

59
Q

Malaria:

A

A disease caused by a protist that causes recurrent episodes of fever and can be fatal.

60
Q

Measles:

A

​A serious disease caused by a virus that shows symptoms of fever and a red skin rash.

60
Q

Non-communicable disease:

A

A disease which cannot be spread between individuals.

61
Q

Monoclonal antibodies:

A

Antibodies produced from a single clone of cells that are specific to one binding site on one protein antigen.

62
Q

Non-specific defence:

A

​General physical and chemical barriers that defend the body against lots of different types of pathogen.

63
Q

Salmonella:

A

A bacterial disease that is spread by bacteria ingested in food and can cause a fever, abdominal cramps, vomiting and diarrhoea.

63
Q

Pathogens:

A

Microorganisms that cause infectious disease.

64
Q

Placebo:

A

A substance designed to be indistinguishable from a drug being tested
but has no actual effect on the patient.

64
Q

Preclinical drug testing:

A

Drug testing done in a laboratory using cells, tissues and live animals.

65
Q

Rose black spot:

A

A fungal disease where purple or black spots develop on leaves, which often turn yellow and drop early.

66
Q

Side effects:

A

Other additional effects that the drug has that are different from the expected effect of the drug.

67
Q

Tobacco Mosaic Virus (TMV):

A

A widespread plant pathogen affecting many species of plants which produces a mosaic pattern on the leaves and limits the plant growth.

68
Q

Vaccination:

A

The process of ​ ​introducing small quantities of dead or inactive forms of a pathogen into the body to stimulate the white blood cells to produce antibodies.

69
Q

White blood cell:

A

An important type of cell that makes up the immune system and produces antibodies and antitoxins.

Biology AQA (4 decks)

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