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GCSE Biology > Infection and Response > Flashcards

Infection and Response Flashcards

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1
Q

Examples of protist diseases.

A
  • Malaria
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1
Q

Examples of viral diseases.

A
  • Measles (humans)
  • HIV (human immunodeficiency virus) (humans)
  • TMV (tobacco mosaic virus) (plants)
  • HPV (humans)
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2
Q

Examples of fungal diseases.

A
  • Rose black spot
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3
Q

Examples of bacterial diseases.

A
  • Salmonella
  • Gonorrhoea
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4
Q

What is meant by a pathogen?

A

A microorganism that causes infectious diseases.

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5
Q

How does bacteria cause illness?

A
  • They reproduce rapidly inside the body (every 20 mins under ideal conditions)
  • They produce harmful chemicals called toxins that damage tissues and make us feel ill.
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6
Q

How do viruses cause illness?

A
  • They reproduce rapidly inside the body.
  • They invade host cells.
  • Then they live and reproduce inside cells and cause damage to cells eg cells burst open and dies when the virus leaves.
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7
Q

Examples of pathogens:

A
  • Viruses
  • Bacteria
  • Protists
  • Fungi
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8
Q

What are communicable diseases spread by?

A

Pathogens

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9
Q

How are virus different to bacteria, state one way.

A

Viruses cannot reproduce outside of a cell, they can only reproduce inside a host cell, while bacteria can reproduce anywhere.

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10
Q

True or false, viruses can reproduce anywhere?

A

False, they can only reproduce inside a host cell

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11
Q

3 ways pathogens can be spread:

A
  • Air eg water droplets from sneezing
  • Water - sewages etc
  • Direct contact - sexual contact or sharing needles
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12
Q

How can the spread of pathogens be reduced (5 ways)

A
  • Providing ppl w clean drinking water. eg chlorine in water in UK kills microbes
  • Washing hands before eating.
  • Reducing direct contact between individuals eg condom.
  • Isolation of an infected individual
  • Vaccines
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13
Q

True or false, viruses can be killed by antibiotics?

A

False. Bc viruses live and reproduce within cells, by using antibiotics to kill viruses we would have to in turn destroy the host cell they live in.

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14
Q

Symptoms of measles:

A
  • Fever
  • Red-skin rash
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15
Q

How is the measles virus spread?

A

When droplets in air from sneezes and coughs of infected person are inhaled by an uninfected person, leading to the virus passing into them.

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16
Q

Consequences of measles:

A
  • Measles can cause fatal complications such as damage to the breathing system and the brain.
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17
Q

How can measles be prevented?

A

Vaccination.

Most children are vaccinated against measles at a young age.

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18
Q

Symptoms of HIV:

A

Flu-like illness (initially), at this point the virus is attacking body cells.

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19
Q

How is HIV spread?

A
  • Sexual contact
  • Exchange of bodily fluids eg drug users sharing blood.
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20
Q

Consequences of HIV

A
  • Virus attacks body’s immune cells, unless successfully controlled by antitretroviral drugs in early-stage HIV.
  • This attack leads to late-stage HIV aka AIDs (FATAL) -> at this point, the body’s immune cells are so badly damaged they can no longer deal with infections or cancers.
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21
Q

How can HIV be prevented?

A
  • Using condoms during sex
  • Not sharing needles
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22
Q

How is early-stage HIV treated?

A

Antiretroviral drugs.

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23
Q

How do antiretroviral drugs work?

ad + disadvantages x 2 each

A

They stop the virus from multiplying inside the patient so the virus doesn’t damage the patients immune system.

+ Patients don’t go on to develop AIDs
+ Patients can lead a normal life expectancy
- Antiretroviral drugs are not a cure for HIV
- Patient must take them daily

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24
Q

Symptoms of Salmonella food poisoning:

A
  • Fever
  • Abdominal cramps
  • Vomiting
  • Diarrhoea

^^Bacteria secrete toxins which cause these symptoms.

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25
Q

Salmonella food poisoning is caused by what type of pathogen?

A

Bacteria

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26
Q

How is salmonella food poisoning spread?

A

By ingesting infected food (food prepared in unhygienic conditions)

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27
Q

How is salmonella food poisoning prevented?

A
  • By vaccinating poultry such as chickens.
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28
Q

What type of pathogen is gonorrhoea caused by?

A

Bacteria

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29
Q

How can gonorrhoea be prevented?

A
  • Using a condom during sexual intercourse.
  • Individuals who have unprotected sex should go for regular testing so if it is detected they can be treated before they spread it.
  • Antibiotics (before penicillin was used but now ABR strains have formed so other antibiotics are now used).
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30
Q

Symptoms of Gonorrhoea:

A
  • Yellow or green discharge from penis or vagina
  • Pain when urinating.
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31
Q

What type of pathogen is HIV caused by?

A

Virus

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32
Q

What type of pathogen is measles caused by?

A

Virus

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33
Q

What type of pathogen causes the malaria disease?

A

Protist.

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34
Q

How is malaria caused (life-cycle of malaria pathogen)

A
  • Mosquito bites infected person and now pathogen passes into it.
  • The mosquito is now a vector.
  • Mosquito bites uninfected person and the malaria pathogen passes into their bloodstream.
  • The person now becomes infected with the malaria pathogen.
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35
Q

Can malaria be spread directly from person to person?

A

No.

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36
Q

What is meant by a vector?

A

An organism that transmits disease-causing pathogens from one host to another.

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37
Q

What are the symptoms of malaria?

A
  • Recurrent episodes of fever
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38
Q

How can the spread of malaria be reduced

A

KILL THE VECTORS + PREVENT THEM FROM BREEDING

  • Drain areas of stagnant water because mosquitos breed there
  • Spray areas of stagnant water with insecticide

issue? we can’t kill all the mosquitos
solution? physically prevent vectors from biting humans

  • Using mosquito nets to sleep
  • Spraying mosquito nets with insecticide
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39
Q

What are the 2 types of defence systems in the human body?

A
  • The non-specific defence system
  • The immune system
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40
Q

What is the job of the non-specific defence system?

A

To prevent pathogens from entering the human body.

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41
Q

How does the skin prevent pathogens from entering the human body? 3 points.

A
  • Dead cells on outer layer make it difficult for pathogens to penetrate.
  • Sebum produced by skin is an oily substance that can kill BACTERIA.
  • When skin is damaged, skin scabs over.
42
Q

How does the nose prevent pathogens from entering?

A

Nose has hair and mucus which trap pathogens before they can enter the breathing system.

If pathogens still enter, trachea and bronchi solve this,

43
Q

How does the trachea and bronchi prevent pathogens from entering?

A
  • They are covered in tiny hairs called cilia.
  • Cilia is covered in mucus which traps the pathogen.
  • Cilia wafts mucus into the throat, and mucus is swallowed into the stomach (HCL kills pathogens)
44
Q

How does the stomach play a role in the non-specific defence system?

A
  • Contains HCL which kills pathogens before they can make their way into the digestive system.
45
Q

What type of pathogen does sebum kill?

A

Bacteria.

46
Q

What do white blood cells control/do?

A
  • Phagocytosis
  • Production of antibodies
  • Production of antitoxins
47
Q

Describe what happens during phagocytosis (4 marks).

A
  • WBC detect the chemicals released by pathogen
  • They move towards pathogen
  • They ingest and engulf pathogen
  • And use enzymes to attack and destroy the pathogen
48
Q

What are antibodies?

A

Proteins produced by WBC

49
Q

Explain how antibodies protect the body from pathogens.

A
  • WBC release antibodies which bind to the pathogen (how?)
  • Pathogen has antigen on their surface which a specific complementary antibody can bind to.
  • When antibodies bind to complementary antigen on pathogen it triggers the pathogen to be destroyed/killed by WBC.
  • Antibodies are specific and remain in the blood for a long time
  • So if individual is infected again with the pathogen, the antibodies specific to that pathogen can protect us OR complementary antibodies will be produced at a faster rate by WBC.
  • At that point, the person is said to be immune to the pathogen.

(lymphocytes = WBC that produce antibodies and antitoxins)

50
Q

Explain how antitoxins protect the body from toxins produced by bacteria? (4 marks)

A
  • WBC produce antitoxins
  • Which bind to the toxins produced by bacteria which infect the human.
  • And neutralise the toxins
  • This prevents them from damaging cells
51
Q

2 types of plant diseases:

A
  • Tobacco mosaic virus (TMV)
  • Rose black spot
52
Q

What type of pathogen causes tobacco mosaic virus?

A

Virus.

53
Q

What type of plants is TMV common in?

A

Tomatoes.

54
Q

What is the visual consequence of TMV?

A
  • Discolouration on plant leaves in a mosaic pattern
55
Q

What is the consequence of TMV?

(4 marks)

A
  • Discolouration
  • Less chlorophyll
  • Rate of photosynthesis is reduced
  • Growth is reduced because less glucose produced to bind to nitrate ions in soil to produce amino acids for proteins.
56
Q

What type of pathogen causes rose black spot?

A

Fungus

57
Q

Visual consequences of rose black spot.

A

Leaves of plant develop purple or black spots, then plant turns yellow and leaves fall off.

58
Q

Consequences on plant if it has rose black spot.

A
  • Black and Purple spots and yellow discolouration
  • Means less chlorophyll
  • So rate of photosynthesis has decreased
  • Growth is reduced because less glucose produced to bind to nitrate ions in soil to produce amino acids for proteins.
59
Q

How can rose black spot be spread?

A
  • Water
  • Wind
60
Q

How can rose black spot be treated?

A
  • By spraying plant with fungicides which kill fungi.
  • Remove and destroy infected leaves
61
Q

Explain how vaccinations help with immunity (6 marks)

A
  • A small quantity of dead or inactive forms of a pathogen are introduced into the body.
  • This stimulates the WBC to produce antibodies specific to the pathogen.
  • At the same time, the WBC continues to divide by mitosis to make more genetically identical ones which also produce more of the same specific antibody.
  • These antibodies, called memory cells stay in the blood for a very long period.
  • So if the same pathogen re-enters into the body the WBC can respond quickly to produce the correct antibodies, or memory cells pathogens can remember pathogen and detect thru toxins, engulf and destroy pathogen.
  • So the individual doesn’t get infected.
62
Q

How come vaccinations don’t lead to illnesses?

A

Because the pathogens introduced to the body are dead or inactive.

63
Q

Describe how the concept of ‘herd immunity’ helps to protect individuals within a population from infectious diseases. Include in your answer an explanation of how vaccination contributes to achieving herd immunity.

A
  • In a population some individuals may not get vaccinated due to various reasons eg new to country etc.
  • This means they are not protected or immune to an infectious disease.
  • So if majority of the population are immunised and vaccinated against a specific pathogen the spread of the pathogen can be reduced and the unvaccinated person won’t get infected.
  • This process called ‘herd immunity’ protects individuals within a population from infectious diseases.
64
Q

Advantages and disadvantages of vaccination:

A

AD
- They have eradicated and prevented many diseases
- Epidemics can be prevented
- Herd immunity

DISAD
- Bad reactions such as fevers can occur
- Not always effective

65
Q

What is meant by an antibiotic?

A

A medication that kills INFECTIVE bacteria inside the body without harming body cells (in order to get rid of a bacterial disease).

66
Q

Example of antibiotic

A

Peniicillin (the first antibiotic used to kill Gonorrhoea)

67
Q

How does antibiotic resistance occur?

A
  • Mutations occur in bacteria during reproduction that makes them resistant to antibiotic resulting in certain bacteria no longer being killed by antibiotics - the bacteria has evolved
  • So when these bacteria are exposed to the antibiotics only the non-resistant strain die.
  • The resistant strain survives and lives on to reproduce identical offspring meaning the population of resistant bacteria increases.
  • The means antibiotics that were previously effective no longer work = antibiotic resistance.

^^Occurs when antibiotics are overused -> so doctors are careful when doctors prescribe antibiotics they are careful; they make sure they always treat specific bacteria with specific antibiotics.

68
Q

Why can’t doctors prescribe antibiotics for viral infections?

What can doctors prescribe instead?

A
  • Antibiotics can’t kill viruses
  • bc viruses live and reproduce inside host cells, so cells and tissues would have to be destroyed and damaged if virus was intended to be killed.

Instead doctors can prescribe painkillers which treat the symptoms of diseases by relieving pain, however painkillers don’t kill pathogens/treat the disease itself.

69
Q

How can antibiotic resistance be prevented?

A
  • Doctors should prescribe antibiotics appropriately ONLY for bacterial infections.
  • Finish the course of antibiotics to ensure ALL bacteria is killed and none is left alive to mutate.
70
Q

What plant does the heart drug digitalis come from?

A

Foxglove plant

71
Q

Where does pain-killer aspirin come from?

A

Willow trees

72
Q

Where did the antibiotic penicillin come from?

A

The mould ‘Penicillium’ by Alexander Fleming.

73
Q

Where do drugs originate from typically?

A
  • Plants
  • Microorganisms eg mould
74
Q

Who invented penicillin?

A

Alexander Fleming

75
Q

What are drugs tested and trialed for?

A

Toxicity - safe for humans

Effectiveness - to treat disease

Best (optimal) dose - The best does to treat the disease while creating the fewest side effects

76
Q

Stages in drug testing:

A

1) Pre-clinical testing
- Not carried out on humans bc drug may be toxic, instead testing is carried out on cells, living animals and tissues.

2) Clinical testing

  • Carried out on humans
    Part 1: Low doses of drug given to HEALTHY humans to ensure the drug
    is safe for humans
    Part 2: The Double Blind test
    Active drug and placebo drug is given to two groups by doctors. Volunteers and doctors are unaware of who has the active or placebo drug. This
  • eradicates the presence of bias bc doctors won’t focus on particular volunteers more than others.
  • And increases reliability.

3) Peer-review
results are peer-reviewed by other scientists and checked for repeatability.

77
Q

Placebo

A

Tablet or injection that contains no active drug.

78
Q

Explain the double-blind test:

A
  • Active drug and placebo drug is given to two groups by doctors.
  • Volunteers and doctors are unaware of who has the active or placebo drug.
  • This eradicates the presence of bias bc doctors won’t focus on particular volunteers more than others.
  • And increases reliability.
79
Q

What type of white blood cells make antibodies and antitoxins?

A

(B) Lymphocytes.

80
Q

What do lymphocytes do?

A

They produce antibodies against against pathogens which bind to the antigen on the surface of the pathogen.

81
Q

Explain how monoclonal antibodies are produced.

A
  • Mouse is injected with the pathogen we want to produce mAB for.
  • Lymphocytes in mouse are now stimulated to produce antibodies specific to the pathogen.
  • These lymphocytes are collected.
  • Lymphocytes cannot divide by mitosis so are fused to a tumour cell to produce a hybridoma cell.
  • Hybridoma cell is cloned - it continues to divide RAPIDLY by mitosis in a Petri dish to produce several clones of identical hybridoma cells that all produce the same antibody.
  • The antibodies are collected and purified.

REMEMBER THIS OCCURS IN LABS!

82
Q

What is meant by a monoclonal antibody?

What allows them to be so useful in medicine?

A

Antibodies that are produced from a single clone of hybridoma cells.

This means they are specific to one binding site on one protein antigen.

^^This allows for monoclonal antibodies to be able to target specific chemicals or cells in the body, so have many uses in medicine.

83
Q

Why are monoclonal antibodies commonly used in medicine?

A

They are specific to one binding site on one protein antigen.

^^This allows for monoclonal antibodies to be able to target specific chemicals or cells in the body, so have many uses in medicine.

84
Q

What can monoclonal antibodies be used for in medicine?

A
  • for diagnosis such as in pregnancy tests (AB bind to hormones)
    *To measure hormone levels in blood, and levels of other chemicals in the blood.
    *To detect pathogens in blood.
    *For research to locate or identify specific molecules in a cell or tissue by binding to them with a fluorescent dye
    *To treat some diseases: for cancer the monoclonal antibody can be bound to a radioactive substance, a toxic drug or a chemical which stops cancer cells from growing and dividing. It delivers the substance to the cancer cells without harming other cells in the body because mAB are specific.

REMEMBER; they bind to the specific molecule/cell etc to carry out job.

85
Q

Disadvantages of monoclonal antibodies:

A

Monoclonal antibodies create more side effects than expected.

(They are not yet as widely used as everyone hoped when they were first developed).

86
Q

How can plant diseases be detected (6 ways)?

A
  • stunted growth
  • spots on leaves
  • areas of decay (rot)
  • growths
  • malformed stems or leaves
  • discolouration
  • the presence of pests eg aphids.
87
Q

How can we IDENTIFY the detected disease on plants? x 3 ways

A
  • reference to a gardening manual or website
  • taking infected plants to a laboratory to identify the pathogen
  • using testing kits that contain monoclonal antibodies.
88
Q

Plant diseases can be caused by pathogen, these are called pathogen diseases what other type of plant disease is there?

A

Plant ion deficiency diseases.

89
Q

Example of insect that attack plants to cause disease.

A

Aphids.

90
Q

What do aphids do to plants?

A
  • Extract nutrients such as sugars and amino acids from plants.
  • This stunts its growth, bc less glucose to bind to nitrate ions in soil to make amino acids to make proteins.
91
Q

2 example of plant ion deficiency disease:

A

Plants can be damaged by a range of ion deficiency conditions:
* stunted growth caused by nitrate deficiency.
* chlorosis caused by magnesium deficiency.

92
Q

Lack of nitrate ion causes (nitrate ion deficiency disease)

A

Stunted growth.

Because nitrate ion is needed for protein synthesis in plants by binding w glucose to make amino acids, and therefore growth.

93
Q

Lack of magnesium ion causes (magnesium ion deficiency disease)

A

Chlorosis.

Magnesium is required to make chlorophyll. Less magnesium = less chlorophyll = chlorosis.

In chlorosis, plants lose their green colouration = less growth bc less glucose to bind w nitrate ions to produce amino acids to make proteins.

94
Q

In plants what are nitrate ions used for?

A

Proteinsynthesis.

95
Q

In plants what are magnesium ions used for?

A

To make chlorophyll.

96
Q

What are the 3 main types of plant defence systems?

A
  • Chemical defence responses
  • Mechanical defence responses
  • Physical defence responses
97
Q

Examples of physical defence responses:

A

Physical defence responses to resist invasion of microorganisms.

  • Cellulose cell walls (difficult to penetrate)
  • Tough waxy cuticle on leaves (difficult to penetrate)
  • Layers of dead cells around stems (bark on trees) which fall off (barrier to entry from micro-organisms)

These protect the plant from invasion of microorganisms such as bacteria from attacking plant etc.

98
Q

Examples of chemical defence responses:

A

Chemical plant defence responses.
* They release antibacterial chemicals which kill bacteria to prevent them from attacking plant.
* Poisons to deter herbivores from grazing on plant

99
Q

Examples of mechanical defence responses

A

Mechanical adaptations.
* Thorns and hairs deter animals (irritate mouth of herbivores)
* Leaves which droop or curl when touched to scare herbivores bc they aren’t used to plants that move like this
* Mimicry to trick animals

100
Q

Phagocytes are;

A

WBC that engulf

101
Q

Lymphocytes are;

A

WBC that release AB or antitoxins

102
Q

Why are placebos used?

A

As a control to compare effects of treatment.

GCSE Biology (12 decks)

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