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Biology > 4.1 - C - Communicable Diseases > Flashcards

4.1 - C - Communicable Diseases Flashcards

1
Q

Define pathogen

A

An organism that causes disease

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2
Q

What are the 4 types of pathogen?

A

Bacteria
Fungi
Protoctist
Virus

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3
Q

Explain what bacteria are and do and give 2 examples

A 
Prokaryote
Smaller than eukaryotes
Reproduce rapidly
Damage cells by releasing toxins
Eg: tuberculosis, ring rot in potatoes
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4
Q

Explain what fungi are and do and give 2 examples

A

Often lives in skin
Reproductive hyphae grow into skin and release pores
Hyphae form a mycelium
Lives in vascular tissue (plants) to gain nutrients (from xylem and phloem)
Hyphae release extracellular digestive enzymes to break down cellulose
Eg: black Sigatoka (bananas), ring worm

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5
Q

Explain what proctosits are and do and give 2 examples

A

Enter hosts and feed on contents of cells

Eg: potato blight, malaria

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6
Q

Explain what viruses are and do and give 2 examples

A

They invade cells and take over genetic machinery
The cause cells to reproduce copies of the virus
The host cell bursts and new viruses are released, the cycle repeats
Eg: HIV, influenza

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7
Q

What are the 2 types of ways diseases can be transferred

A

Direct

Indirect

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8
Q

Give 5 examples of direct transfer of diseases

A 
Physical contact
Airborne
Spores
Sneezing/coughing etc.
Water/food
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9
Q

Give 1 example of indirect transfer of diseases

A

Vectors (ie. mosquitoes)

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10
Q

Give 7 factor which affect disease transmission

A 
Homelessness
Human migration
Poor ventilation
Poor health
Poor diet
Poor hygiene
Overcrowding
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11
Q

Explain tuberculosis and the organism that causes it

A

A disease that affects many parts of the body, killing the cells and tissues; the lungs are most often affected
Bacteria:
Mycobacterium tuberculosis

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12
Q

Explain bacterial meningitis and the organism that causes it

A

Infection of the meninges - the membranes that surround the brain and spinal chord; the membranes become swollen and may cause damage to the brain and nerves
Bacteria:
Neisseria meningitidis or Streptococcus pneumonia

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13
Q

Explain ring rot (in plants) and the organism that causes it

A

Ring of decay in the vascular tissue of a potato tuber or tomato, accompanied by leaf wilting
Bacterium:
Clavibacter michiganensis subsp. sepedonicus

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14
Q

Explain HIV/AIDS and the organism that causes it

A

Attacks cells in the immune system and compromises the immune response
Virus:
Human immunodeficiency virus

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15
Q

Explain influenza and the organism that causes it

A

Attacks the respiratory system and causes muscle pains and headaches
Virus:
From the Orthomyxoviridae family - “flu” viruses

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16
Q

Explain tobacco mosaic virus and the organism that causes it

A

Causes mottling and discolouration of leaves
Virus:
Tobacco mosaic virus

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17
Q

Explain black sigatoka (bananas) and the organism that causes it

A

Causes leaf spots on banana plants reducing yield
Fungus:
Mycosphaerella fijienis

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18
Q

Explain blight (tomatoes and potatoes) and the organism that causes it

A

Affects both leaves and potato tubers
Protoctistan:
Phytophtora infestans

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19
Q

Explain ringworm (cattle) and the organism that causes it

A

Growth of the fungus in skin with pore cases erupting through the skin causing a rash
Fungus:
Trichophyton verrucosum

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20
Q

Explain athlete’s foot and the organism that causes it

A

Growth under the skin of feet - particularly between the toes
Fungus:
Trichophyton rubrum

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21
Q

Explain malaria and the organism that causes it

A

Parasite in the blood that causes headaches and fever and may progress to coma and death
Protoctistan:
Plasmodium falciparum

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22
Q

What are the 4 stages of a pathogen’s life cycle?

A

Travel from 1 host to another (Transmission)
Entering the host’s tissues
Reproducing
Leaving the host’s tissues

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23
Q

Define direct transmission

A

Passing a pathogen from host to new host with no intermediary

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24
Q

Define indirect transmission

A

Passing a pathogen from host to a new host, via a vector

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25
Q

Define transmission

A

Passing a pathogen from an infected individual to an uninflected individual

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26
Q

What is a vector?

A

An organism that carries a pathogen from one host to another

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27
Q

Define inflammation

A

Swelling and redness of tissue caused by infection

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28
Q

What are coughing, sneezing and vomiting examples of?

A

Expulsive reflexes

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29
Q

Why are primary defences non-specific?

A

They can prevent more diseases

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30
Q

What is an expulsive reflex?

A

When irritation causes a reaction, expelling the pathogen

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31
Q

What do histamine and anti-histamine do?

A

Histamine - causes inflammation, allows immune system to act

Anti-histamine - reduces inflammation

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32
Q

Define callose

A

A large polysaccharide deposit that blocks old phloem sieve tubes

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33
Q

What do plants not have?

A

An immune system

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34
Q

What are the 2 types of passive defence in a plant?

A

Chemical and physical

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35
Q

Give 5 examples of passive defences

A

Cellulose cell wall - physical barrier waterproofed by lignin and contain tannins
Waxy cuticle - prevents water collecting which can contain pathogens
Bark - physical barrier, contains chemicals which will work against pathogens
Tylose formation - tylose is a balloon like projection which fills the xylem, acts as a plug, prevents the spread of pathogens. Has high levels of terpenes which are toxic to many pathogens.
Callose

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36
Q

What is the one type of active defence in plants?

A

Chemical

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37
Q

Give 4 things active defence in plants include

A

Cell walls become thickened and strengthened with additional cellulose
Deposition of callose between the plant cell wall and cell membrane near the invading pathogen
Oxidative bursts damage cells of invading organisms
Increase in production of chemicals

38
Q

Give 5 chemicals used in active defence in a plant

A

Terpenoids - Range of essential oils with antibac and anti fungal properties. Also creates scents.
Phenols - Antibac and anti fungal properties. Tannins in Bari inhibit insect’s attacks. Pathogen transmission drops by high amounts of tannins ingested by insects, causing death.
Alkaloids - nitrogen-containing compounds. Give herbivores a bitter taste. Some inhibit protein synthesis.
Defensins- defensive proteins
Hydrolytic enzymes
(See book)

39
Q

What are tannins?

A

Chemical defences which are activated if a pathogen is detected

40
Q

What is canker?

A

A sunken necrotic lesion in the woody tissue such as the main stem or branch. It causes death of the cambium tissue in the bark.

41
Q

What is necrosis?

A

Deliberate cell suicide. Sacrifices are made to save the rest of the plant. Stops spread of pathogens.

42
Q

What are primary defences?

A

Those that prevent pathogens entering the body

43
Q

What is a mucous membrane?

A

Specialised epithelial tissue covered by mucus

44
Q

What do the clotting factors activate?

A

An enzyme cascade

45
Q

What does histamine do?

A

Causes vasodilation - makes capillary walls permeable to phagocytic white blood cells and proteins

46
Q

Give 8 examples of primary defences

A

Skin
Blood clotting/skin repair
Mucous membranes
Coughing/sneezing/vomiting - expulsive reflexes
Inflammation
Eyes protected by antibodies and enzymes in tear fluid
Ear wax
Mucus plug in the cervix of the female reproductive system, maintaining acidic conditions in the pussy

47
Q

What is an antigen-presenting cell?

A

A cell that isolates the antigen from a pathogen and places it on the plasma membrane so that it can be recognised by other cells in the immune system

48
Q

Define clonal selection

A

Selection of a specific B or T cell that is specific to the antigen

49
Q

What are cytokines?

A

Hormone-like molecules used in cell signalling to stimulate the immune response

50
Q

What is a neutrophil?

A

A type of white blood cell that engulfs foreign matter and traps it in a large vacuole (phagosome) which fuses with lysosomes to digest the foreign matter

51
Q

What are opsonins?

A

Proteins that bind to the antigen on a pathogen and then allow phagocytes to bind
Antibodies that make it easier for phagocytes to engulf the pathogen

52
Q

What is the purpose of secondary defence?

A

To combat pathogens that have entered the body

53
Q

Define phagocytosis

A

The first line of secondary defence.

Specialised cells in the blood and tissue fluid engulf snd digest pathogens.

54
Q

What are lymphocytes and phagocytes involved in?

A

Lymphocytes - specific immune response

Phagocytes - non-specific response

55
Q

Describe what happens in phagocytosis

A

Neutrophil binds to opsonise attached to antigen of the pathogen
Pathogen engulfed by endocytosis forming a phagosome
Lysosomes fuse to the phagosome and release lyric enzymes into it
After digestion, the harmless products can be absorbed by the cell

56
Q

What is the first line of secondary defenceL

A

Phagosytosis

57
Q

What are macrophages a type of?

A

Phagocyte

58
Q

Explain macrophages

A

Lager cells, made in bone marrow. Travel in blood as monocytes then settle in body tissues.
They initiate responses to invading pathogens.
When engulfing pathogens, they don’t fully digest them.
The antigen on the pathogen is moved to a special protein complex on the surface of the cell. It becomes the antigen-presenting cell.
It exposes antigen on its surface so other cells recognise it.

59
Q

What are the 2 types of antigen immunity?

A

Antigen presentation

Specific immune response

60
Q

Explain antigen presentation

A

Antigen presenting cells move around the body where it can come into contact with specific cells that can activate full immune response. Involves T and B lymphocytes

61
Q

Explain specific immune response

A

Clonal selection produces antibodies that combat specific pathogens and memory cells that will provide long-term immunity.

62
Q

Define antibody

A

Specific proteins released by plasma cells that can attach to pathogenic antigens

63
Q

Define clonal expansion

A

An increase in the number of cells by mitosis cell division

64
Q

What are interleukins?

A

Signalling molecules that are used to communicate between different white blood cells

65
Q

What are the 4 types of cells that T lymphocytes develop/differentiate into and what are their functions?

A

T helper cells - release cytokines that stimulate B cells to develop and stimulate phagocytosis by the phagocytes.
T killer cells - which attack and kill host-body cells that display the foreign antigen
T memory cells - which provide long-term immunity
T regulator cells - which shut down the immune response after the pathogen has been successfully removed. They are also involved in preventing autoimmunity

66
Q

What are the 2 types of cells that B lymphocytes develop into and what are their functions?

A

Plasma cells - which circulate in the blood, manufacturing and releasing the antibodies
B memory cells - which remain in the body for a number of years and act as the immunological memory

67
Q

What are autoimmune diseases?

Give 2 examples

A

When the immune system attacks a part of the body.
When antibodies start to attack our own antibodies.
Lupus, arthritis

68
Q

What are agglutinins?

A

Antibodies that cause pathogens to stick together

69
Q

What are anti-toxins?

A

Antibodies that render toxins harmless

70
Q

How many polypeptide chains are in an antibody?

How are they held together?

A

4

Disulphide bonds

71
Q

What is the purpose of the constant region?

A

For binding to phagocytes

72
Q

What is the purpose of the hinge region?

A

Allows flexibility

73
Q

What is the purpose of having more than one variable region?

A

Allows attachment to more than one antigen - agglutination

74
Q

What is the purpose of the variable region?

A

Binds to antigens

75
Q

Define active immunity

A

Where the person’s own immune system is activated and manufactures its own antibodies

76
Q

Define passive immunity

A

Immunity acquired without the activation of the lymphocytes, it’s achieved when antibodies are passed to the individual from another person’s immune system (breastfeeding, injections, etc.)

77
Q

Define natural immunity

A

Immunity gained in the normal course of living

78
Q

Define artificial immunity

A

Immunity achieved as a result of medical intervention/deliberate exposure to antibodies or antigens

79
Q

Define epidemic

A

A rapid spread of disease through a high proportion of the population

80
Q

Explain ring vaccination

A

Vaccinating all people living with or near the victim
It contains the spread in a ring
It requires people to report victims

81
Q

Explain nerd vaccination

A

Vaccinating all people at risk

Stops infection spreading

82
Q

Give an example of natural active immunity

A

As a result of infection

83
Q

Give a result of artificial active immunity

A

Injection of weakened antigens

84
Q

Give an example of natural passive immunity

A

Across the placenta/breast milk

85
Q

Give an example of artificial passive immunity

A

Injections of antibodies

86
Q

Give 7 reasons why people may choose not to get immunised

A 
Too busy/cba
Media scare stories
Concerned about side effects
Allergic to vaccine
Fear of needles
Religious reasons
Vaccine is expensive
87
Q

Give 3 reasons why governments want people to be vaccinated (other than direct health benefits)

A

Prevention of disease - less sick days, less harm to economy
Costs less to vaccinate than treat
Health service may not cope if lots get infected

88
Q

Define antibiotic

A

A chemical which prevents the growth of microorganisms

They can be antibacterial or antifungal

89
Q

Define personalised medicine

A

The development of designer medicines for individuals

90
Q

Define synthetic biology

A

The re-engineering of biology. This could be the production of new molecules that mimic natural processes, use of natural molecules to produce new biological systems that do not exist in nature.

91
Q

Give 3 reasons why new drugs are needed

A

New diseases are emerging
There are still many diseases for which there are no effective treatments
Some antibiotic treatments are becoming less effective

Biology (25 decks)

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