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A Level Biology > Health And Disease > Flashcards

Health And Disease Flashcards

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1
Q

What is a pathogen?

A

A microorganism that can cause disease

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2
Q

What are 3 examples of Viruses

A
  • HIV/AIDS
  • Influenza
  • Tobaco Mosaic Virus (TMV)
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3
Q

How does influenza cause flu?

A

Infection of the epithelial cells - killing them leading them open to more infection.

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4
Q

What animals does the flu affect?

A

Mammals, including humans, pigs and birds - chickens.

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5
Q

What does HIV stand for?

A

“Human Immunodeficiency virus” (HIV)

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6
Q

What does AIDS stand for?

A

“Acquired Immunodeficiency Syndrome”

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7
Q

How does HIV cause illness?

A

Virus affects T helper cells which destroys immune system. This leaves people vulnerable to other diseases (e.g. pneumonia)

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8
Q

How is HIV transmitted?

A
  • Unprotected sex
  • Contaminated needles
  • Contaminated blood products
  • Mother - foetus during pregnancy.
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9
Q

Is there a cure for HIV?

A

There is no vaccine or cure, but drug treatments can slow the progress of the disease.

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10
Q

How many plant species does TMV infect?

A

150 plant species

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11
Q

What plants does TMV affect?

A

Tomatoes, peppers, cucumbers, petunias and delphiniums

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12
Q

How does TMV manifest itself?

A
  • Damaged leaves, flowers and fruit with a mosaic pattern.

- Stunting growth and reduced yield, leading to almost total crop loss.

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13
Q

What size are viruses compared to bacteria?

A

0.02-0.3 micrometers

50x smaller than bacteria

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14
Q

Describe the structure of a virus

A

RNA or DNA surrounded by protein shell.

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15
Q

How do viruses cause illness?

A

Invade living cells and take over biochemistry so host makes more viruses.
- Rapidly evolve and are always pathogenic

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16
Q

What are 3 examples of Fungi?

A

Athlete’s foot, Black Sigatoka and Ringworm

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17
Q

What is the pathogen causing Athlete’s foot?

A

Tinia Pedia

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18
Q

What is Athlete’s foot?

A

A form of human ringworm that grows on and digests the warm, moist skin between the toes.

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19
Q

How does Athlete’s foot manifest?

A

Causes cracking and scaling, which is itchy and may become sore.

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20
Q

What treatment is there for athlete’s foot?

A

Anti-fungal creams are an effective cure

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21
Q

What is Black Sigatoka?

A

A banana disease caused by the fungus “Mycosphaerella fijensis”

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22
Q

How does Black Sigatoka cause illness in bananas?

A

Attacks and destroys the leaves.

- The hyphae penetrate and digest the cells, turning the leaves black.

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23
Q

What problems are caused by Black Sigatoka?

A

50% reduction in yield

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24
Q

What is a treatment for Black Sigatoka?

A

Fungicide (chemical that kills fungi) treatment can control the spread of the disease but there is no cure.

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25
Q

What is ringworm?

A

Fungal disease

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26
Q

What animal species does ringworm affect?

A

Mammals, including cattle, dogs, cats and humans

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27
Q

How does ringworm manifest?

A

Grey-white, crusty, infectious, circular areas of skin

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28
Q

What type of pathogen is a saprophyte (define it)

A

Fungi - saprophytes feed on dead and decaying matter.

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29
Q

How do fungi reproduce?

A

Millions of tiny spores are produced, which can spread rapidly through crop plants.

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30
Q

Describe the structure of a bacteria

A

Prokaryote with no membrane-bound nucleus or organelles.

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31
Q

How do bacteria replicate?

A

Binary fission (every 20mins)

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32
Q

What 2 ways can bacteria be classified?

A

By their cell wall - which react different to grain staining - its cell wall affects its ability to react to different antibiotics.

Can be classified by shape e.g. rod-shaped, spherical, comma shaped etc…

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33
Q

What are 3 examples of Bacteria

A

Bacterial meningitis, Ring rot and Tuberculosis (TB)

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34
Q

How does bacterial meningitis cause illness?

A

Meningitis affects the brain, which can spread into the rest of the body causing septicaemia (blood poisoning) and rapid death.

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35
Q

How does bacterial meningitis manifest?

A

Blotchy red/purple rash that doesn’t disappear when glass is pressed against it.

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36
Q

What treatment is used for meningitis?

A

Antibiotics can cure the disease

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37
Q

What plant species does ring rot affect?

A

Potatoes, tomatoes and aubergines

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38
Q

How does ring rot affect plants?

A

Damages leaves and fruit
It can destroy up to 80% of the crop and there is no cure.
Once bacterial ring rot infects a field, it cannot be used to grow potatoes again for at least two years.

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39
Q

What animal species does TB (Tuberculosis) affect?

A

Humans, cows, pigs, badgers and deer.

40
Q

How does TB cause illness?

A

TB damages and destroys lung tissues and suppresses the immune system.

41
Q

What is the treatment for TB?

A

Antibiotics - but it is also preventable by improving living standards

42
Q

What are 2 examples of protists?

A

Blight and Malaria

43
Q

What plants do blight affect?

A

Tomato blight and potato blight

44
Q

How does blight affect plants?

A

Destroys leaves and fruit, causing millions of pounds worth of crop damage each year

45
Q

What is the pathogen for malaria?

A

Plasmodium - complex life cycle with two hosts: mosquitos and people

46
Q

How is malaria spread?

A
  • Spread by bites of infection: inside two hosts - people and mosquitoes
47
Q

How does malaria cause illness?

A

Invades red blood cells, liver and even brain.

48
Q

How many people die each year of malaria

A

600,000 people

49
Q

How can malaria be treated?

A

No vaccine and limited cures - but preventative measures.

- Can control vector - insecticides and removing standing water, mosquito nets, long-sleeved clothing

50
Q

What is direct transmission?

A

The transmission of a pathogen directly from one individual to another

51
Q

What are 3 examples of direct transmission?

A
  • Direct contact (kissing and other body fluids)
  • Inoculation (break in a skin, animal bite, puncture wound, such as a needle)
  • Ingestion (taking contaminated food and drink)
52
Q

What is indirect transmission?

A

Where the pathogen travels from one individual to another indirectly

53
Q

What are 3 examples of indirect transmission?

A
  • Fomites (inanimate objects such as bedding, socks etc)
  • Droplet infection (inhalation) - minute droplets of saliva and mucus are expelled from your mouth as you talk, cough or sneeze.
  • Vectors (a vector can transmit communicable pathogens from one host to another).
54
Q

What are factors that affect transmission?

A
  • Overcrowded living and working conditions
  • Poor nutrition
  • A compromised immune system
  • Poor disposal of waste in humans
  • Culture and infrastructure
  • Climate change
  • Socioeconomic factors
55
Q

What are examples of direct transmission in plants?

A

Ring rot, TMV, tomato blight and black Sigatoka

56
Q

What are examples of indirect transmission in plants?

A
  • Soil contamination

- Vectors

57
Q

What are examples of vectors that can lead to indirect transmission?

A
  • Wind
  • Water
  • Animals
  • Humans
58
Q

What physical defences do plants have?

A
  • When plants are under attack, they can produce high levels of callose
  • Callose is synthesised between cell walls and cell membrane next to the infected cells.
  • Lignin is also added to these walls which make the barrier to invasion stronger and thicker.
59
Q

What are plants chemical defences?

A
  • insect repellent e.g. citronella from lemongrass
  • anti fungal compounds e.g. phenols
  • general toxins - Some plants make chemicals that can be broken down to form cyanide compounds when the plant cell is attacked. Cyanide is toxic to most living things.
60
Q

What are the 3 lines of defence?

A
  1. Innate non-specific (primary) defences
  2. Innate non-specific (secondary) defences
  3. Adaptive specific immune response
61
Q

What was the purpose of the first line of defence?

A
  1. Keeping pathogens out
62
Q

What was the purpose of the second line of defence?

A

Getting rid of pathogens

63
Q

What is the purpose of the last line of defence?

A

Targeting pathogens and immunity

64
Q

What are examples of front line defences?

A
  • Skin
  • Mucous membranes
  • Expulsive reflexes (coughing, sneezing, vomiting, diarrhoea)
  • Blood clotting (platelets)
  • Inflammatory response (histamines, cytokines)
65
Q

What are examples of second line defences?

A
  • Phagocytes (neutrophils and macrophages; phagocytosis; antigen presentation)
  • chemical messengers (cytokines; opsonins)
  • fever
66
Q

What is an example of third line defence?

A

Lymphocytes (B cells & T cell; immunological memory)

67
Q

What is a leukocyte?

A

white blood cells

68
Q

What are the 2 types of phagocytes?

A

Neutrophils and Macrophages

69
Q

Describe a Neutrophil

A
  • “Lobed-nucleus”
  • 60% of all leukocytes (white blood cells)
  • Travel in blood: squeeze through the capillary walls into tissue
  • Released in large numbers during infection
  • Short lived
70
Q

Describe a macrophages

A
  • Larger than neutrophils
  • Found in organs
  • Leave the bone marrow as immature monocytes
  • Monocytes develop into macrophages as they settle in organs
  • Long lived
71
Q

What is an opsonin?

A

chemicals that bind to pathogens and make them readily identifiable by the phagocyte.

72
Q

What are the stages of phagocytosis?

A
  1. Phagocyte attracted by chemicals produced by pathogen.
  2. Phagocyte recognised the pathogens as non-self and binds to it.
  3. Phagocyte engulfs the pathogen to form phagosome - lysosome moves towards phagosome and combine
  4. In the phagolysosome, enzymes break down the pathogen.
  5. Digested pathogen absorbed by phagocyte - antigens combine with MHC in the cytoplasm.
  6. HMC (Major histocompatibility complex)/antigen complex is displayed on phagocyte membrane making an antigen presenting cell.
73
Q

What does the adaptive specific immune response do?

A

Provide immune system with the ability to:

  • Recognise and remember specific pathogens - “immunological memory”
  • Mount stronger attacks each time a pathogen is encountered - primary immune response and secondary immune response.
74
Q

What are lymphocytes?

A

White blood cells

  • smaller than phagocytes
  • large nucleus that almost filled the cell
  • made in the bone marrow
75
Q

What are the 2 types of lymphocytes.

A

B lymphocytes and T lymphocytes

76
Q

Describe B lymphocytes

A
  • Remain in the bone marrow until mature
  • Congregate in lymph nodes and spleen
  • Have highly specific antibodies in the membrane; each B cell can only produce one type of antibody and each B cell is unique.
  • Once correct B cell is selected, cell is cloned and stimulated to differentiate to produce plasma/effectors (which produce antibodies) and memory cells.
  • Attack pathogens in circulation as part of the “humoral response”.
77
Q

Describe T lymphocytes

A
  • Mature in the thymus
  • Have highly specific receptors in membrane
  • Once correct T cell is activated, T cell with various jobs can be produced (‘helpers’, ’killers’, ‘memory’, ‘regulators’)
  • ‘Cell mediated response’
78
Q

What are the 4 main types of T lymphocytes?

A
  • T helper cells
  • T killer cells (cytotoxics)
  • T memory cells
  • T regulators cells
79
Q

What are the 3 main types of B lymphocytes?

A
  • Plasma cells
  • B effector cells
  • B memory cells
80
Q

What are the 4 stages of cell communication and specific immune response?

A
  1. Antigen is encountered
  2. Clonal selection
  3. Clonal expansion
  4. Differentiation
81
Q

What is cell-mediated immunity?

A

In cell mediated immunity, T lymphocytes respond to the cells of an organism has been changed in some way.

82
Q

What is humoral immunity?

A

In humoral immunity (B cells), the body responds to antigens found outside the cells.

83
Q

What are autoimmune diseases?

A

Autoimmune diseases refers to when the immune system stop recognising the ‘self’ cells and starts to attack healthy body tissue. Sometimes this is due to the T regulator cells not working effectively.

84
Q

What are antibodies?

A

Y-shaped glycoproteins called immunoglobulins (polypeptides) - bind to specific antigen on the pathogen or toxin that has triggered immune response.
- There are millions of different antibodies: there is a specific antibody for each antigen.

85
Q

Describe the structure of an antibody

A
  • Two identical long polypeptide chains (heavy chain) and two much shorter identical chains (light chain)
  • Had antigen binding sites
  • the chains are held together by disulphides bridges within the polypeptides chains holding them in shape.
  • Variable region, hinge region and constant region
86
Q

How many amino acids, does the binding site of an amino acid have?

A

110 amino acids

87
Q

What part of the antibody gives it its specificity?

A

Variable region

88
Q

What is formed when an antibody binds to an antigen?

A

An antigen-antibody complex

89
Q

How do antibodies defend the body?

A
  1. The antibody of the antigen-antibody complex acts as an opsonin so the complex is easily engulfed and digest it by phagocytes.
  2. Most pathogens can no longer effectively invade the host cells once they’re part of the antigen-antibody complex.
  3. Antibodies acts as agglutinins causing pathogen is carrying antigen-antibody complex is to clump together. This helps prevent the, spreading through the body and makes it easier for phagocytes to engulf a number of pathogens at the same time.
  4. Antibodies can act as anti-toxins, binding to the toxins produced by pathogens and making them harmless.
90
Q

What is natural active immunity?

A

The body has itself acted to produce antibodies and/or memory cells. These antibodies result in the destruction of the antigens.

91
Q

What is natural passive immunity?

A

Immunity acquired passively (used by a new-born baby) e.g. antibodies cross the placenta into the fetus. In addition, colostrum, which is very high in antibodies, is transferred through breastmilk.

92
Q

What is artificial passive immunity?

A

For certain potentially fatal diseases, antibodies are formed in one individual (often an animal), extracted and then injected into the bloodstream of another individual - giving temporary immunity, which may not last long, but can be lifesaving.

93
Q

What is artificial active immunity?

A

Immune system of a body is stimulated to make its own antibodies to a safe form of an antigen (a vaccine), which is injected into the bloodstream (vaccination). The pathogen is made safe so that there is no risk of infection.

94
Q

What are pharmacogenetics?

A

The science of interweaving knowledge of drug actions with personal genetic material.

95
Q

What is personalised medicine?

A

A combination of drugs that work with your individual combination of genetics and disease.

96
Q

What is synthetic biology?

A

This is the use of genetic engineering to develop populations of bacteria to produce much-needed drugs that would otherwise be too rare. Nanotechnology is another stand of synthetic biology, where tiny non-natural particles are used for biological purposes.

A Level Biology (13 decks)

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