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GCSE Biology > B3 - Infection & Response > Flashcards

B3 - Infection & Response Flashcards

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1
Q

What are pathogens?

A

Pathogens are microorganisms that cause infectious disease

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2
Q

What are 3 examples of viral diseases?

A
  • Measles
  • HIV
  • Tobacco mosaic virus
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3
Q

What are 2 examples of bacterial diseases?

A
  • Salmonella

- Gonorrhoea

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4
Q

What is an example of a fungal disease?

A

Rose black spot

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5
Q

What is an example of a protist disease?

A

Malaria

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6
Q

What engulfs and digests pathogens?

A

White blood cells (phagocytes)

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7
Q

What are the four types of pathogen?

A

Virus, protozoa, bacteria, fungus.

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8
Q

Which pathogen needs a host cell to reproduce and what does this make them?

A

Viruses. They are therefore not cells and are always pathogens.

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9
Q

Describe how a virus reproduces.

A

Viruses enter body cells & reproduce inside them, destroying the body cell.

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10
Q

What are pathogens?

A

Microorganisms which cause communicable disease.

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11
Q

From smallest to largest, what order do the types of pathogens come?

A

Viruses → bacteria → fungi → protozoa.

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12
Q

What is a eukaryote?

A

An organism which has cells with nuclei or a cell with a nucleus. Eukaryotes are complex and include all animals and plants.

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13
Q

Describe bacteria.

A

They are very small prokaryotic cells, about 1/100th the size of a body cell
They reproduce rapidly inside the body
They make you feel ill by producing toxins that damage cells and tissues
However, they aren’t always parasites

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14
Q

Describe viruses.

A

Not cells
About 1/100th the size of a bacterium
Make you feel ill by reproducing rapidly inside cells

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15
Q

In what ways can pathogens be spread?

A

Ingested substances (water, food)
Air
Direct contact

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16
Q

Name 3 viral diseases.

A

Measles
HIV
Tobacco mosaic virus

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17
Q

How is measles spread?

A

By droplets of fluid from an infected person’s sneeze/cough.

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18
Q

What are the symptoms of measles?

A

Fever and red skin rash
Can be fatal if there are complications
E.g. can lead to pneumonia or a brain infection called encephalitis

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19
Q

How can measles be treated?

A

Most people are vaccinated against it when they’re young

If not, the disease must run its course

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20
Q

How is HIV spread?

A

Sexual contact

Exchanging bodily fluids, such as blood- e.g. when sharing needles taking drugs

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21
Q

What are the symptoms of HIV?

A
  • Initially, flu-like symptoms for a few weeks
  • Usually, no other symptoms are experienced for several years
  • During this time, HIV can be controlled by antiretroviral drugs which stop the virus replicating
  • The virus weakens the immune system by attacking immune cells. If it’s badly damaged, the body can’t cope with other infections, or cancers
  • At this stage, HIV is known as late stage HIV infection or AIDS
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22
Q

HIV cannot be cured; how can it be prevented?

A
  • Barrier contraception

- Not sharing needles

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23
Q

How is TMV spread? What does it affect?

A

Via vectors. Affects many species of plants

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24
Q

What are the symptoms of TMV?

A
  • Causes a mosaic pattern on leaves- parts become discoloured
  • Discolouration means that plants can’t carry out photosynthesis as well
  • TMV therefore inhibits growth
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25
Q

TMV can’t be treated; how can it be prevented?

A

Field hygiene and pest control.

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26
Q

What kind of disease is rose black spot?

A

Fungal.

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27
Q

How is rose black spot spread?

A

Through water and wind.

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28
Q

What are the symptoms of rose black spot?

A
  • Causes purple/black spots to develop on the leaves of rose plants
  • The leaves can then turn yellow and drop off
  • Therefore, less photosynthesis can happen, so growth is inhibited
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29
Q

How can rose black spot be treated?

A

Using fungicides

Stripping the plant of its affected leaves, which should be destroyed so that the fungus can’t spread to other plants

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30
Q

What causes malaria?

A

A protist.

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31
Q

How is malaria spread?

A
  • Part of the malarial protist’s life cycle takes place inside the mosquito
  • The mosquitoes are vectors- they pick up the protist when feeding on an infected animal
  • When a mosquito feeds on an infected animal, it infects it by inserting the protist into the animal’s blood vessels
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32
Q

What are the symptoms of malaria?

A

Causes repeating episodes of fever. It can be fatal.

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33
Q

How can the spread of malaria be reduced?

A

Stopping mosquitoes from breeding.

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34
Q

How can people be protected from getting malaria from mosquitoes?

A
  • Use insecticides

- Use mosquito nets

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35
Q

Why is malaria so difficult to get rid of?

A
  • It is spread by mosquitoes
  • It is constantly evolving
  • It has several stages to its life cycle; each stage requires different ways to eradicate
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36
Q

How does salmonella spread?

A

It is foodborne: eating food contaminated with salmonella bacteria

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37
Q

What are the symptoms of salmonella?

A

Food poisoning caused by toxins the bacteria produces:

  • fever
  • stomach cramps
  • vomiting
  • diarrhoea
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38
Q

How can salmonella be prevented?

A
  • Avoiding contamination
  • Food hygiene
  • Most poultry in the UK is vaccinated against salmonella to control the spread
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39
Q

How is gonorrhoea spread?

A

It is an STD so by sexual contact

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40
Q

What are the symptoms of gonorrhea?

A
  • Pain when urinating

- Thick yellow/green discharge from the vagina/penis

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41
Q

How is gonorrhoea treated?

A

Antibiotics

42
Q

How should gonorrhea be prevented?

A

Barrier contraception, e.g. condoms

43
Q

Give three terms for diseases that easily spread

A
  • Contagious
  • Communicable
  • Infectious
44
Q

Give 4 ways the spread of disease can be reduced/prevented.

A
  • Hygiene - e.g. washing hands before cooking/after sneezing
  • Destroying vectors - e.g. using insecticides or destroying insects’ habitats so that they can’t breed
  • Isolating infected individuals
  • Vaccination
45
Q

What 5 features does the body have which stop a lot of pathogens entering?

A
  • Skin acts as a barrier and secretes antimicrobial substances which kill pathogens.
  • Hairs and mucus in the nose trap particles that could contain pathogens.
  • The trachea and bronchi secrete mucus to trap pathogens.
  • Trachea and bronchi are lined with ciliated cells which waft the mucus up to the back of the throat, where it can be swallowed.
  • Stomach produces hydrochloric acid which kills pathogens that have entered the digestive system
46
Q

In what 3 ways can the immune system attack pathogens?

A

Phagocytosis
Producing antibodies
Producing antitoxins

47
Q

What is phagocytosis?

A

Phagocytes, a type of white blood cell, engulf foreign cells/pathogens and digest them with enzymes.

48
Q

Explain how the immune system produces antibodies.

A
  • Every type of pathogen has a unique molecule, called an antigen, on its surface
  • When lymphocytes come across a foreign antigen, they start to produce specific antibodies which lock onto the invading cells
  • They are then found and destroyed by other white blood cells
  • Antibodies are then produced rapidly and carried around the body to find all similar pathogens
    If the person is infected with that pathogen again lymphocytes will rapidly produce specific antibodies- they are naturally immune to that pathogen
49
Q

What are antitoxins specific to?

A

They counteract toxins produced by invading bacteria

50
Q

What is a benefit of using vaccinations as opposed to letting the immune system deal with infection?

A

When infected with a new pathogen, it takes a few days for the immune system to fully respond. By then, you can already be quite ill, so vaccinations are a pre-empt to this

51
Q

What do vaccinations involve?

A
  • A small amount of dead/inactive pathogens are injected
  • These carry antigens, which cause the immune system to produce specific antibodies, even though the vaccine is harmless
    If live pathogens of the same type enter the body after that, they are recognised
  • White blood cells can then rapidly produce antibodies to kill them, so you don’t get ill
52
Q

What does the MMR vaccine contain?

A

Weakened versions of the viruses that cause measles, mumps and rubella

53
Q

What do painkillers do?

A

They relieve pain and help to reduce symptoms of infection, but don’t deal with the cause of disease or kill pathogens

54
Q

Give an example of a painkiller

A

Aspirin

55
Q

How to antibiotics work?

A
  • They kill/prevent growth of invading bacteria without killing body cells
  • Different antibiotics kill different types of bacteria
  • Antibiotics have greatly reduced the number of deaths from communicable diseases caused by bacteria
56
Q

Why can’t antibiotics be used to treat viruses?

A

Viruses reproduce inside body cells. This makes it difficult to develop drugs that just kill the virus and not cells as well

57
Q

How do bacteria become resistant to antibiotics?

A

Bacteria can mutate, causing some to become resistant to an antibiotic
When treating an infection, some of the bacteria might be resistant to the antibiotic you use
This means that only the non-resistant strains will be killed
The resistant bacteria will survive and reproduce, the population increasing (this is an example of natural selection)
The resistant strain could cause a serious infection that can’t be treated by antibiotics

58
Q

Give an example of an antibiotic resistant bacteria

A

MRSA causes serious wound infections and is resistant to the powerful antibiotic methicillin

59
Q

What should be done to slow down the development of strains of resistant bacteria?

A
  • Doctors should avoid over-prescribing antibiotics

- People should finish their whole course of antibiotics, rather than stopping once they feel better

60
Q

Plants produce a variety of chemicals to protect themselves against pests and pathogens. A lot of our current medicines were discovered by studying plants used in traditional cures. Give two examples

A
  • Developed from a chemical found in willow, aspirin is used as a painkiller and to lower fever
  • Developed from a chemical found in foxgloves, digitalis is used to treat heart conditions
61
Q

What is the name for the drug industry?

A

The pharmaceutical industry

62
Q

What are the 3 main stages of drug testing?

A

Preclinical testing
Testing on animals
Clinical trials

63
Q

What does preclinical testing involve?

A

Testing drugs on human cells and tissues in a lab

64
Q

When testing drugs on live animals, what 3 things are investigated?

A
  • Efficacy (how effective it is)
  • Toxicity (whether it’s harmful)
  • Dosage (how much, how often)
65
Q

What are the 2 stages of clinical trials?

A
  • Testing on healthy human volunteers (to make sure it doesn’t have harmful side effects when the body’s working normally). Dosage is gradually increased.
  • Testing on people suffering from the illness. Optimum dosage is found (most effective, with the fewest side effects)
66
Q

What is a placebo?

A

A tablet that does not contain an active drug ingredient and has no effect

67
Q

What is the placebo effect?

A

When a patient expects a treatment to work, so feels better, regardless of whether it has had an effect

68
Q

What two types of trialling do clinical trials typically involve?

A

Blind trials

Double blind trials

69
Q

What are blind trials?

A

Patients are study are divided into 2 groups, one which receive the drug and the other a placebo (but the individuals don’t know which they get).

The doctor can see the actual effect of the drug, allowing for the placebo effect.

70
Q

What are double blind trials?

A
  • Patients in a study are divided into 2 groups, one which receive the drug and the other a placebo
  • Neither the individuals nor the doctor know which the patients get until the results are gathered
  • This is so that the doctors, when monitoring and analysing, aren’t subconsciously influenced by their knowledge
71
Q

Name and describe 3 ways the human body defends against the entry of pathogens

A
  • Skin – barrier
  • Nose - nasal hairs , mucus and cilia,
  • Trachea & bronchi – mucus to catch, cilia to remove from lungs,
  • Stomach - HCl acid kills.
72
Q

What is an antigen?

A

A protein on the surface of a pathogen

73
Q

Why will the antibody produced for measles not be effective in other diseases?

A

Antibody has a specific shape which fits with a specific antigen

74
Q

Why are dead or inactive pathogens used in a vaccine?

A

To stimulate white blood cells to make antibodies without causing the disease

75
Q

What happens if the live pathogen invades the body after being vaccinated?

A

White blood cells able to respond much faster and produce more antibodies quicker to destroy the pathogens so the person doesn’t suffer the symptoms of the disease

76
Q

What is an antibiotic and what is it used for?

A

Kills bacteria inside the body without harming human cells

77
Q

Why is there a growing concern about bacterial resistance to antibiotics?

A

The resistant bacteria are not killed and can continue to multiply inside the body making the person very ill and infecting others too

78
Q

Which one of these statements is true? :

  • Painkillers are used to treat the symptoms of a disease and kill the pathogens which cause it
  • Painkillers are used to kill the pathogens causing a disease
A

Painkillers are used to treat the symptoms of a disease but do not kill the pathogens

79
Q

Number these statements to show the process of drug testing

  • Drugs are trialled on live animals
  • Drugs are trialled on people with the disease the drug is for
  • Drugs are trialled in laboratories on cells and tissue cultures
  • Drugs are trialled on healthy volunteers
A
  1. Drugs are trialled in laboratories on cells and tissue cultures
  2. Drugs are trialled on live animals
  3. Drugs are trialled on healthy volunteers
  4. Drugs are trialled on people with the disease the drug is for
80
Q

Why are placebos used?

A

A placebo is used to check that there are no other factors which
may cause the patient’s condition to improve without the drug

81
Q

What are the applications of monoclonal antibodies?

A
  • Pregnancy testing
  • Used to measure levels of hormones and other chemicals in blood
  • Treat some cancers by delivering a toxic drug to the cancer cells
  • To find various molecules in cells or tissues by binding to them with a fluorescent dye
82
Q

Why do some people feel the use of monoclonal antibodies is unethical?

A
  • Mouse has to suffer the disease deliberately
  • Mouse is induced to have cancer
  • Treatment not always safe
  • It’s very expensive and money could be better used
83
Q

Name 3 ways you can detect that a plant is diseased.

A
  • Leaf spots/discolouration - Growths
  • Malformed stems or leaves
  • Presence of pests
  • Stunted growth
  • Areas of decay (rot)
84
Q

Describe why nitrate ions are very important for plants.

A

Nitrate is crucial for protein synthesis and hence growth. Without sufficient nitrate ions, the plant would be stunted

85
Q

What is chlorosis and how can it be prevented?

A

Chlorosis is the yellowing of the leaves. It can be prevented by providing the plant with magnesium

86
Q

Why would a test kit containing monoclonal antibodies be useful to detect plant disease?

A

The monoclonal antibodies can be used to detect a particular chemical which is only present in one type of pathogen. This would then show whether the plant was infected with this disease or not

87
Q

Give an example of a drug extracted from microorganisms.

A
  • Alexander Fleming was clearing out some petri dishes containing bacteria
  • He noticed that one dish also had mould on it, and that the area around the mould was free of bacteria
  • He found that the mould was producing a substance, called penicillin, which killed the bacteria
88
Q

The results of drug testing aren’t published until they’ve been through peer review. What is this and why is it used?

A

1) Peer review is when other scientists check that the work has been carried out rigorously and that the results have been interpreted validly.
2) This helps to prevent false claims.

89
Q

What type of blood cell produces antibodies?

A

B-lymphocytes

90
Q

What are monoclonal antibodies?

A

Identical antibodies produced from clones of a hybridoma. These antibodies are used to target one specific protein antigen.

91
Q

Describe how monoclonal antibodies are produced. (6 marks)

A

1) A mouse is injected with the antigen that the antibodies have been chosen to target.
2) The mouse produces B-lymphocytes specific to this antigen.
3) These are collected from the mouse.
4) Because B-lymphocytes can’t reproduce quickly, they are fused with tumour cells (which very much can).
5) This forms hybridoma cells, which are cloned to form a ball of cells.
6) The ones which successfully produce antibodies are selected.
7) The antibodies of these hybridomas are collected and purified - these are monoclonal antibodies.

92
Q

Give 3 uses of monoclonal antibodies.

A

Pregnancy tests.
Treating diseases.
Laboratory research.

93
Q

How are monoclonal antibodies used in pregnancy tests? (6 marks)

A

The part of the stick which is urinated on contains monoclonal antibodies specific to the hormone HCG, found in the urine of pregnant women. Blue dye is attached to the antibodies.

  • If you’re pregnant: the hormone binds to the mobile antibodies in the part you wee on. The urine moves up the stick, carrying the hormone and the dye. The dye and hormone bind to the immobile antibodies in the test strip (part that turns blue if preggies), getting stuck there and turning it blue.
  • If you’re not pregnant: as the urine moves up the stick, it still carries the antibodies attached to the blue dye with it. But there is no HCG to bind to them, so the blue dye doesn’t get stuck to the test strip and so it doesn’t go blue.
94
Q

How are monoclonal antibodies used to treat cancer? (6 marks)

A

1) Body cells have specific antigens on their surface; you can make monoclonal antibodies specific to these.
2) Cancer cells have antigens on their membranes (tumour markers) that aren’t on normal body cells.
3) You can make MAs that will bind to these markers.
4) An anti-cancer drug (e.g. a radioactive substance, toxic drug, or chemical which prohibits growth) can be attached to these MAs.
5) The MAs are given to a patient through a drip.
6) They target and kill the cancer cells w/o killing any normal body cells near the tumour.

95
Q

What is the advantage of using monoclonal antibodies to treat cancer, over other treatments?

A

Other treatments (chemotherapy and radiotherapy) affect normal body cells as well as the cancerous ones, whereas MAs target specific cells. So the side effects of an antibody-based drug are lower than that of these other treatments.

96
Q

How are monoclonal antibodies used in laboratory research? Give 3 examples of their use.

A

Can be used to:

1) Bind to chemicals in blood (e.g. hormones) to measure their levels.
2) Test blood samples for certain pathogens.
3) Locate specific molecules in a cell/tissue.
This is done by making MAs specific to the substance, then binding them to a fluorescent dye. The substance is detectable by the presence of this dye (because the MAs bind to the substance being tested for).

97
Q

Why are monoclonal antibodies not as widely used as scientists had origninally hoped?

A

They cause more side effects (e.g. fever, vomiting, low blood pressure) than expected; initially, scientists had thought this wouldn’t be the case, as they target specific cells/molecules.

98
Q

Give 2 examples of mineral ion deficiency symptoms in plants.

A

1) Nitrate deficiency: nitrates are needed to make proteins for growth. A lack causes stunted growth.
2) Magnesium ion deficiency: magnesium is needed for making chlorophyll for photosynthesis. Plants who lack it suffer from chlorosis and have yellow leaves.

99
Q

Give 7 common signs of disease in plants.

A 
Stunted growth
Abnormal growths, e.g. lumps
Malformed stems/leaves
Spots on leaves
Discolouration
Patches of decay
Infestation of pests
100
Q

Give 3 examples of physical disease defences that plants have to prevent entry of pathogens.

A

Waxy cuticle on leaves and stems provides a barrier.
Cell walls (made of cellulose) form another.
Layers of dead cells around stems, e.g. bark on trees.

101
Q

Give 2 examples of chemical defences that plants have.

A

Some produce antibacterial chemicals, e.g. the mint plant and witch hazel.
Others produce poisons which deter herbivores, e.g. tobacco plants, foxgloves and deadly nightshade.

102
Q

Give 2 examples of mechanical defences that plants have.

A

1) Some have thorns and hairs that stop animals touching/eating them.
2) Others have leaves that droop/curl when something touches them, which knocks off insects and moves them away from things.
3) Some can mimic other organisms; e.g. the passion flower’s leaves have bright yellow spots which look like butterfly eggs, preventing other butterflies from laying their eggs there.

GCSE Biology (7 decks)

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