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Biology > Module 4: Disease and the Immune system > Flashcards

Module 4: Disease and the Immune system Flashcards

1
Q

What is a disease?

A

A condition that impairs the normal functioning of an organism.

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2
Q

What is a communicable disease?

A

A disease that spreads from organism to organism.

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3
Q

Name an animal disease caused by bacteria.

A

•tuberculosis
•bacterial meningitis

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4
Q

Name a plant disease caused by bacteria.

A

Ring rot
(potatoes, tomatoes)

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5
Q

Name an animal disease caused by fungi.

A

•ringworm
•athlete’s foot

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6
Q

Name a plant disease caused by fungi.

A

Black Sigatoka
(banana plants)

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7
Q

Name a disease in plants caused by protoctista.

A

Potato/tomato late blight.

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8
Q

Name an animal disease caused by protoctista.

A

Malaria

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9
Q

Name a plant disease caused by a virus.

A

Tobacco mosaic virus

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10
Q

Name an animal disease caused by a virus.

A

•HIV/AIDs
•influenza

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11
Q

Give an example of direct transmission.

A

Droplet transmission (coughing/sneezing).

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12
Q

What is direct transmission?

A

When the pathogen is spread directly from one organism to another.

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13
Q

What is indirect transmission?

A

When the pathogen is spread though something else.

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14
Q

Give an example of indirect transmission.

A

Though air, water, food.

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15
Q

What is a vector?

A

Anything that carries the pathogen from one host to the next.

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16
Q

What is a non-specific defence?

A

Something that prevents pathogens entering the body. They are the same for all pathogens.

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17
Q

Give some examples of non-specific defences in humans.

A

*skin
*mucous membranes
*tears
*stomach acid
*blood clotting
*wound repair
*expulsive reflexes
*inflammation

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18
Q

How does the skin act as a defence against pathogens?

A

*physical barrier
*layer of dead skin cells - hard for pathogens to penetrate
*sebaceous glands secrete sebum (slightly acidic) - prevents growth of harmful bacteria
*covered with harmless microorganisms - compete for resources - reduce growth of pathogens

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19
Q

What are lysozymes?

A

Enzymes that destroy bacteria by digesting their cell walls.

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20
Q

How do mucous membranes act as a defence against pathogens?

A

*line openings
*secrete mucous - traps microorganisms to be destroyed by phagocytes
*contain lysozymes

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21
Q

How do tears act as a defence against pathogens?

A

They contain lysozymes.

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22
Q

How does the stomach acid act as a defence against pathogens?

A

Hydrochloric acid kills pathogen’s in food and water - pH too high.

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23
Q

What are expulsive reflexes?

A

The body’s automatic responses to irritation to remove foreign bodies.

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24
Q

Give some examples of expulsive reflexes.

A

*sneezing
*coughing
*vomiting
*diarhhoea

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25
Q

What is a blood clot?

A

A mesh of protein fibres (fibrin).

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26
Q

How do blood clots as a defence against pathogens?

A

Plug wounds to reduce blood loss prevent pathogens entering.

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27
Q

How are blood clots formed?

A

*when the endothelium gets damaged, platelets become exposed to proteins outside of this
*this activates the platelets, which form a plug and release clotting factors

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28
Q

How does wound repair happen?

A

*outer layer of skin cells divide and migrate to edges of wound
*the tissue below contracts and brings the edges closer
*collagen fibres repair the wound

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29
Q

What are signs of inflammation?

A

*swelling
*redness
*pain
*heat

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30
Q

How does inflammation occur?

A

*damaged tissue activates mast cells which release histamines
*this causes vasodilation, to increase blood supply, which brings more white blood cells to the area and also increases temperature, so pathogens have less ability to reproduce
*histamines also make blood vessel walls more permeable, so more plasma leaves forming more tissue fluid, causing swelling and pathogens to be isolated

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31
Q

How does the waxy cuticle act as a defence against pathogens?

A

*physical barrier that is hard for pathogens to penetrate
*prevents water collecting on the leaves, so reduces the chance of infection by antigens carried in water

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32
Q

How do cell walls act as a defence against pathogens?

A

They are a physical barrier that make it harder for pathogens to enter cells.

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33
Q

What is callose?

A

A polysaccharide produced by plants that is deposited between cell walls and plasma membranes.

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34
Q

When is callose deposited?

A

In times of stress, e.g. during pathogen invasion.

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35
Q

How does callose act as a defence against pathogens?

A

*makes it harder for pathogens to enter cells
*when deposited in the plasmodesmata, it limits the spread of viruses between cells

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36
Q

What are plasmodesmata?

A

Small channels in plant cell walls.

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37
Q

Give some examples of chemical plant defences against pathogens.

A

*antimicrobial chemicals
*chemicals that are toxic to insects

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38
Q

How do chemicals secreted by plants act as a defence against pathogens.

A

*kill pathogens
*inhibit pathogen growth
*prevent infection by insect vectors

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39
Q

What are antigens?

A

Molecules found on the surface of cells.

40
Q

What is meant by non-specific responses?

A

They happen in the same way for all microorganisms.

41
Q

What is meant by specific responses?

A

They are antigen-specific, so only work for specific pathogens.

42
Q

What are the 2 types of white blood cells?

A

Lymphocytes and phagocytes.

43
Q

What are the 2 types of lymphocytes?

A

B and T lymphocytes.

44
Q

Are lymphocytes involved in the specific or non-specific immune response

A

Specific.

45
Q

What are the 2 types of phagocytes?

A

Macrophages and neutrophils.

46
Q

Are phagocytes involved in the specific or non-specific immune response?

A

Non-specific (apart from macrophages - sometimes specific.

47
Q

Where are phagocytes found?

A

In the blood and in tissues.

48
Q

What are opsonins?

A

Molecules in the blood that attach to foreign antigens to aid phagocytosis.

49
Q

What is one way in which opsonins work?

A

Some hide the negative charges on the membrane of the pathogen, making it easier for the negatively charged phagocyte to get closer to the pathogen.

50
Q

What is a phagosome?

A

A vesicle inside a phagocyte, containing the pathogen.

51
Q

What is a lysosome?

A

An organelle containing digestive enzymes.

52
Q

Which white blood cell responds to pathogens first?

A

Neutrophils.

53
Q

What are cytokines?

A

Proteins that act as messenger molecules.

54
Q

Describe phagocytosis.

A

*damaged cells and pathogens release cytokines, attracting phagocytes
*opsonin proteins attach to pathogen and mark them
*phagocytes have receptors which attach to chemicals on pathogens
*phagocytes engulfs pathogen, forming phagosome
*lysozymes hydrolyse pathogen

55
Q

What happens after phagocytosis in macrophages?

A

The macrophage presents the pathogen’s antigens on its surface to activate other immune cells, becoming an APC.

56
Q

What happens after phagocytosis in neutrophils?

A

The products of the digested pathogen are absorbed in the cell, or secreted by exocytosis.

57
Q

What is clonal selection?

A

Specific receptors on T lymphocytes bind only to specific antigens.

58
Q

What is clonal expansion?

A

T lymphocytes with the complementary receptors divide by mitosis to produce clones.

59
Q

What is the cell-mediated response?

A

The response involving T lymphocytes, only activated by antigens on APCs.

60
Q

What do T helper cells do after cloning?

A

*activate B lymphocytes
*stimulate macrophages
*become memory cells
*become cytotoxic T cells

61
Q

How do cytotoxic T cells ‘kill’ cells?

A

They release perforin, which makes holes in the cell’s plasma membranes meaning any substances can enter of exit, so the cell dies.

62
Q

What cells do cytotoxic T cells kill and why?

A

Its own body cells in order to prevent pathogens dividing in them.

63
Q

What are two ways pathogens can cause harm?

A

*directly damaging tissue
*release of toxins

64
Q

How do hot climates increase transmission?

A

*more kinetic energy for chemical reactions
*pathogens reproduce more rapidly

65
Q

What social factors can increase transmission?

A

*poor sewage infrastructure
*lack of freshwater
*poor sanitation
*overcrowded living
*medicine and vaccines less readily available

66
Q

What are the three types of direct transmission in animals?

A

*direct contact
*innocluation
*ingestion

67
Q

Give an example of direct contact.

A

Kissing.

68
Q

Give an example of inncoluation.

A

*animal bites
*sharing needle

69
Q

Give an example of ingestion.

A

Contaminated water.

70
Q

What are the three types of indirect transmission in animals?

A

*vectors
*droplets
*fomites

71
Q

Give an example of a vector.

A

Mosquito.

72
Q

Give an example of droplets.

A

Saliva/sneezing.

73
Q

Give an example of fomites.

A

Dirty bedding.

74
Q

How can direct transmission occur in plants?

A

Direct contact of other plants.

75
Q

What are the two ways indirect transmission can occur in plants?

A

*contaminated soil
*vectors

76
Q

What are the types of plant defences against pathogens?

A

*barriers (waxy cuticle, bark)
*antibacterial chemicals (repel insects and kill pathogens)
*physical defences (prevent pathogens spreading - callose)

77
Q

What happens to the pathogen after it has been hydrolysed?

A

*useful soluble molecules are absorbed in cytoplasm
*antigens are presented on surface of phagocyte

78
Q

Is the second line of defence specific or non-specific?

A

Specific.

79
Q

Where are T and B lymphocytes made?

A

Bone marrow.

80
Q

Where do T lymphocytes mature?

A

Thymus.

81
Q

Where do B lymphocytes mature?

A

Bone marrow.

82
Q

What is the humoral response?

A

The immune response involving B cells and antibodies.

83
Q

What are the three roles of antigens?

A

*agglutination
*mark pathogens
*anti-toxins

84
Q

What is agglutination?

A

Antibodies clumping pathogens together.

85
Q

What do anti-toxins do?

A

Bind to toxins to prevent them entering the cell.

86
Q

What are the two types of B cells?

A

*plasma cells
*B-memory cells

87
Q

What do plasma cells do?

A

Produces antibodies.

88
Q

What do memory cells do?

A

*remain in blood and recognise pathogens on reinfection
*divide rapidly into plasma cells to make antibodies

89
Q

What is an epidemic?

A

When a disease spreads rapidly on a national level.

90
Q

What is a pandemic?

A

When a disease spreads rapidly on a global level.

91
Q

What is herd immunity?

A

When a large percentage of the population is vaccinated, meaning people who can’t have it are still protected.

92
Q

How do antibodies kill bacteria?

A

*prevent cell wall synthesis (inhibit enzymes responsible for making molecules in a cell wall)
*disrupt cell membranes (bind to phospholipids)
*interfere with protein synthesis in bacteria

93
Q

Explain the process of antibiotic resistance.

A

*random mutations in bacterial genetic material
*could code for new proteins, providing selective advantages
*reproduce with these advantages

94
Q

What increase antibiotic resistance?

A

Overuse and misuse of antibiotics.

95
Q

What is personalised medicine?

A

Medicines that are tailored to an individual’s DNA, using genetic information.

96
Q

What is synthetic biology?

A

Using technology to make things such artificial proteins, cells and microorganisms.

Biology (11 decks)

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