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BIOLOGY A LEVEL > Communicable Diseases > Flashcards

Communicable Diseases Flashcards

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1
Q

What is an infectious disease

A

A disease resulting from the infection of a host organism by a pathogen, a disease-causing organism

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2
Q

What are the two categories of bacteria

A

Gram-positive
Gram-negative

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3
Q

What is a zoonotic infection

A

It is a disease that can affect more than one type of organism

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4
Q

What happens when someone is infected with tuberculosis

A

A tissue mass called a tubercle forms around the infected site caused by airborne bacteria

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5
Q

What does tuberculosis do

A

Tuberculosis kills cells and tissues and the lungs are most affected. It affects the respiratory system.

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6
Q

What are the pathogens that cause tuberculosis

A

Mycobacterium tuberculosis and M.bovis

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7
Q

How can tuberculosis be treated

A

Using a course of antibiotics. White blood cells called macrophages engulf the bacteria by phagocytosis, controlling the infection

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8
Q

What is meningitis

A

Meningitis is the infection of the meninges which are the membranes that surround the brain and spinal cord

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9
Q

What happens to the membranes in the brain when infected by meningitis

A

The membranes become swollen and may cause damage to the brain and nerves

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10
Q

What pathogen causes meningitis

A

Neisseria Meningitidis or Streptococcus pneumonia

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11
Q

What happens to the body when infected with meningitis

A

Meningitis can spread into the rest of the body causing septicaemia and rapid death

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12
Q

How can meningitis be treated

A

It can be treated with antibiotics

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13
Q

What does HIV/AIDS do to the body

A

HIV/AIDS targets T helper cells in the immune system of the body. Gradually, it destroys the immune system so affected people are open to other infections. I also compromises the immune response

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14
Q

What pathogen causes HIV

A

Human immunodeficiency virus

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15
Q

What is influenza

A

It is the viral infection of the ciliated epithelial cells in the gas exchange system (the respiratory system). It kills them leaving the airways open to secondary infection.

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16
Q

What does influenza cause

A

Muscle pains and headaches

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17
Q

What pathogen causes influenza

A

Orthomyxoviridae-‘flu’ viruses

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18
Q

What does malaria cause

A

Makes people weak and vulnerable to other infections

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19
Q

What happens when the body is infected with malaria

A

A parasite in the blood that causes headaches and fevers and may progress to coma and death

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20
Q

What pathogen causes malaria

A

Plasmodium falcipanum

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21
Q

What is ringworm

A

The growth of fungus in skin with spore cases erupting through the skin to cause a rash

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22
Q

What pathogen causes ringworm

A

Trichophyton verrucosum

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23
Q

What does ringworm cause

A

A grey-white, crusty, infectious rash in circular areas on skin

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24
Q

What can treat ringworm

A

Antifungus creams

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25
Q

What does what does ringrot damage

A

Damages leaves, tubers and fruits of potatoes, tomatoes and aubergine

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26
Q

What pathogen causes ring rot

A

Gram positive bacteria

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27
Q

What does athlete’s foot cause

A

Growth under skin or feet particularly between the toes. It grows on and digests the warm moist skin between the toes. It causes cracking and scaling which is itchy.

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28
Q

What does tobacco mosaic virus cause

A

Mottling and discolouration of leaves. It causes plants to produce less chlorophyll.

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29
Q

What happens with TMV

A

They may have stunted growth because the reduction in plant chlorophyll content due to TMV means that photosynthesis is reduced

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30
Q

What does black sigatoka cause

A

Causes leaf spots on banana plants reducing yield.

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31
Q

What does hyphae cause in black sigatoka

A

Hyphae penetrate and digest the cells turning the leaves black

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32
Q

Which pathogen causes black sigatoka

A

Mycosphaerella fijiensis

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33
Q

What does blight affect

A

Aubergine

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34
Q

What does blight affect

A

Both leaves and potato tubers

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35
Q

What pathogen causes blight

A

Phytophthora infestans which is a protocist

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36
Q

What does hyphae do in blight

A

They penetrate host cells, destroying leaves, tubers and fruits

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37
Q

State mechanics of disease via direct transmission

A

Inoculation
Ingestion

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38
Q

State mechanics of disease via indirect transmission

A

Droplet transmission via inhalation
Fomites: inanimate objects like bedding, socks and cosmetics
Vectors
Animals and humans

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39
Q

What is a vector

A

A medium that transmits a pathogen from one host to another often animals. Water can also act as a vector

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40
Q

State factors affecting the spread of disease

A

Human demographic
Economic development and land use
Microbial adaptation and change
Breakdown of public health measures
Climate change
International travel

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41
Q

State plant primary defences

A

Waxy cuticle
Bark of tree trunks
Cellulose cell walls

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42
Q

How does recognising an attack take place

A

Some molecules from the pathogen are recognised directly by the plant cells. When pathogenic enzymes break down the cell wall the breakdown products are recognised. Signalling molecules then alert the nucleus to attack. Polysaccharides (callose and lignin) are made to strengthen the cell walls. Defensive chemicals give the alarm to other cells before they are attacked. Some defensive molecules directly attack the pathogen.

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43
Q

Describe callose

A

Callose is deposited between cell walls and membranes next to the infected cells. This barrier prevents further spread. Callose also blocks the sieve cells of the phloem preventing spread wavy. Callose is also deposited in the plasmodesmata of connecting cells

44
Q

What does lignin do

A

Lignin is added to callose to strengthen the barrier

45
Q

How is callose produced

A

When a pathogen is detected, plant cells rapidly produces increased levels of callose.

46
Q

What is callose

A

A polysaccharide made of beta glucose monomers

47
Q

State chemical defences for plants

A

Preventing insects
Repellents
Insecticides
Dealing with pathogens
Defensins
Dealing with fungi
Gossypol
Caffiene
Saponins
Enzymes and toxins
Glucanase

48
Q

What are defensins

A

Plant proteins that disrupt membranes of bacteria and fungi

49
Q

What is saponins

A

Chemicals in plant cell membranes that interfere with fungal cell membranes

50
Q

What does chitinases do

A

They break down fungal cell walls

51
Q

What does glucanase do

A

An enzyme to break down glucans found in oomycetes

52
Q

What is cyanide

A

Toxin in most living organisms

53
Q

Describe gram negative bacteria

A

Have a much thinner peptidoglycan cell wall, but in addition they have an outer membranes containing lipopolysaccharides surrounding the cell and are consequently termed didermis

54
Q

Describe gram positive bacteria

A

They are surrounded by a single thick peptidoglycan cell wall and are therefore termed monodermis

55
Q

What colour does gram positive bacteria appear under a microscope after gram staining

A

Blue-purple

56
Q

What colour does gram negative bacteria appear under a microscope after gram staining

A

Red

57
Q

What are viruses

A

Non living infectious agents. Viruses are a sort section of RNA surrounded by protein.

58
Q

How do viruses infect cells

A

By inserting its own RNA into the DNA of a cell

59
Q

Describe protoctista

A

Eukaryotic cells. They are single celled and multicellular

60
Q

Describe fungi

A

Affects plants hugely. They are eukaryotes, can be unicellular or multicellular. Many fungi are saprophytes. They are made of decaying matter. They often infect the leaves, preventing photosynthesis.

61
Q

How does a toxin damage a cell

A

Toxins damages the cells of the host organism, often by breaking down the plasma membrane or inactivating enzymes.

62
Q

Factors affecting transmission of disease in animals

A

Overcrowding
Poor nutrition
Compromised immune system
Disposal of waste
Climate change
Culture
Socioeconomic factors

63
Q

How do you prevent the spread of disease in animals

A

Hand washing
Improved living and working conditions
Disposal of both bodily and household waste effectively

64
Q

State factors affecting transmission of disease in plants

A

Susceptibility of disease
Overcrowding
Resistance
Climate conditions
Climate change

65
Q

Outline the physical defence processes in plants in response to an infection of a pathogen

A

Callose acts as a barrier when produced to strengthen the cell wall. It is deposited between cell wall and cell membrane. Lignin ua a strengthening agent. Callose blocks sieve cells of phloem. Callose blocks plasmodesmata of adjacent cells.

66
Q

Plants produce chemicals to prevent the infection or spread of pathogen. Describe the role of plant chemicals in disease control

A

Use of insect repellents and antifungals. This prevents insects from spreading disease. Chemicals act to kill pathogens. Chemicals disrupt pathogen functions.

67
Q

What is resistance

A

The ability to ward off disease through various defence mechanisms

68
Q

Describe non-specific (innate) resistance

A

This type of resistance protects against a broad range of pathogens provided by 1st and 2nd lines of defence. It takes form of physical and chemical barriers against infection, as well as phagocytosis and inflammation

69
Q

Describe specific resistance (immune system)

A

This type of resistance is specific to a particular pathogen provided by 3rd line of defence

70
Q

State some non-specific defenses

A

-Skin-physical barrier, produces sebum, an oily substance that inhibits pathogen growth
-Mucous membranes- gas exchanging surfaces have a layer of mucus that traps pathogens. The mucus contains the enzymes, lysozymes (in tears and urine) will destroy bacteria.
-Expulsive reflexes
-Blood clotting
-Inflammatory response

71
Q

Describe some physical barriers

A

Skin- The skin acts as a physical barrier all the way around the body to prevent the entry of bacteria. The skin produces sebum an oily substance that inhibits pathogen growth

72
Q

Describe the lines of defences

A

1st line of defence- skin, tears, mucus, saliva
2nd line of defence- a range of internal defence mechanisms including white blood cells
3rd lines of defence- after pathogen recognition by the immune system. Involved lymphocytes

73
Q

State the role of phospholipases during non-specific defence

A

It kills bacteria by hydrolysing the phospholipids in cell walls and membranes

74
Q

Describe the role of cilia

A

Moves microbes, which are trapped in mucus, towards the mouth and nostrils to be expelled

75
Q

Describe sebum

A

Has antimicrobial activity and with sweat a pH that is unfavourable for microbial growth

76
Q

State the functional role of phagocytosis by white blood cells.

A

Phagocytosis destroys pathogens directly by engulfing and digestion them within specialised vacuoles

77
Q

State the functional role of antimicrobial substances

A

Prevent multiplication of microbes, especially virus

78
Q

State the functional role of antibodies

A

Produced against specific pathogens and bind and destroy pathogens or their toxins

79
Q

Describe the process of blood clotting

A

As well as red blood cells, the plasma also contains platelets. Damage to the plasma also contains platelets. Damage to the blood vessel exposes collagen fibres. The platelets are activated by collagen fibres and change shape forming a temporary ‘platelet plug’. Activated platelets and damaged cells produce a protein called thromboplastin. Thromboplastin then activates a series of enzymes that in the presence of vitamin K and calcium ions convert the protein Prothrombin into the enzyme Thrombin. Thrombin catalyses the conversion of soluble fibrinogen to the insoluble fibrin. When many fibrin molecules have been formed they can polymerise creating a mesh of fibrin that traps more platelets and red blood cells, forming a clot and effectively sealing the wound. The clot (thrombus) dries out and epidermal cells below the scab starts to grow, sealing the wound permanently while damaged blood cells regrow. Collagen deposited provides tissue strength. Once the new epidermis reaches normal thickness and the scab sloughs off

80
Q

What is thromboplastin

A

An enzyme that triggers a cascade of reactions.

81
Q

When is Serotonin released

A

At the same time as thromboplastin

82
Q

What does serotonin do

A

It causes muscles to contract around the wound reducing the gap

83
Q

What is inflammation

A

Inflammation is the swelling of skin immediately around the rupture

84
Q

Describe mast cells

A

They are a type of white blood cells which are activated when skin is ruptured they release histamines and cytokines

85
Q

Describe histamines

A

These make blood vessels dilate, causing localised heat and redness. High temperature prevent pathogen reproducing. Histamines also increase the permeability of the cell wall, causing more tissue fluid to escape causing swelling and the pain.

86
Q

Describe cytokines

A

They attract white blood cells to deal with any pathogen (phagocytes)

87
Q

How is the normal core body temperature controlled

A

By the hypothalamus in the brain

88
Q

How is the body temperature increases during infection

A

The large presence of white blood cells causes the hypothalamus to reset, increasing temperature. This is stimulated by cytokines

89
Q

What is lysozyme

A

An enzyme that disrupts the cell walls of gram-positive bacteria by digesting the peptidoglycan. It is found in human tears, saliva and lysosomes.

90
Q

What are interferons

A

These are proteins produced by virus-infected body cells in response to the virus.interferons trigger the production of a second protein that inhibits viral replication by binding to mRNA cooled by the virus.

91
Q

State the stages of inflammation

A
  1. Increased diameter and permeability of blood vessels. It increases blood flow and delivery of leucocytes to the area. Helps removed destroyed microbes or their toxins. Also lets defensive substances leak into the tissue spaces.
  2. Phagocyte migration and phagocytosis. This directly attacks and destroys microbes and foreign substances
  3. Tissue repair. This replaces damaged cells and tissues, restoring the integrity of the area.
92
Q

State two features of phagocytes important in the response to microbial invasion

A

Ability to squeeze through capillary walls (amoeboid movement), ability to engulf materials by phagocytosis

93
Q

How are phagocytes attracted to the site of infection during inflammation

A

Histamines and prostaglandins attract the phagocytes

94
Q

Why does pus form at the site of infection

A

Pus accumulates at the site of infection where the defence process is most active

95
Q

What is pus

A

Accumulated debris of infection; damaged tissue, dead phagocytes and fluid

96
Q

What is opsonins

A

Coat bacteria and promote attachment of microorganisms to phagocyte. This process is known as opsonisation. Opsonins are produced by phagocytes and tag pathogens making them more visible to other phagocytes

97
Q

Describe neutrophils

A

They act as phagocytes with a multi-lobed nucleus. A bone marrow. There are large numbers of neutrophils released during infection. Neutrophils have a short life-span, once undergone phagocytosis a few times it will die and collect at site as pus

98
Q

Describe macrophages

A

They travel in blood as monocytes. They rest in lymph nodes where mature into macrophages. They are specialised phagosomes. They take longer to break pathogens down than normal phagocytosis.

99
Q

What is clonal selection

A

Activation of T- cell and B- cell

100
Q

State the stages of phagocytosis

A
  • Pathogens produce chemicals and other toxins that attract phagocytes.
  • Phagocytes recognise foreign antigens on pathogens.
  • The phagocyte engulfs the pathogen putting it into a specialised vacuole called a phagosome
  • The phagosomes combined with a lysosomes,which contain powerful digestive enzymes, to form a phagolysosome
  • Enzymes in the phagolysosome break down the pathogens
  • The broken down pathogen is moved out of the phagocyte by exocytosis
101
Q

What happens to pathogens once broken down by macrophages

A

Once broken down the foreign antigens of the pathogens antigens of the pathogens antigens bind with the antigens of the macrophage to form a histocompatibility-complex (MHC). Then they display the antigens on the macrophages plasma membrane to form an antigen-presenting cell (APC)

102
Q

What is the most common type pf phagocytic white blood cell

A

Neutrophils

103
Q

What is the role of chemotaxis in the body’s response to infection

A

Chemotaxis is the method by which phagocytes located infections or damaged tissue. By moving up a chemical gradient, phagocytes are able to locate the source of chemical and therefore the source of the infection or damage

104
Q

How can a blood sample be used to diagnose a microbial infection (without looking for the microbes themselves)

A

By looking at the ratio of white blood cells to red blood cells. An elevated white blood cell count indicates infection.

105
Q

Role of opsonins and phagocyte receptors in enhancing phagocytosis

A

Opsonins coat foreign material, marking it as a target for phagocytosis. The opsonins trigger engulfment of the foreign material by phagocytes

106
Q

Role of opsonins and phagocyte receptors in enhancing phagocytosis

A

Opsonins coat foreign material, marking it as a target for phagocytosis. The opsonins trigger engulfment of the foreign material by phagocytes

BIOLOGY A LEVEL (12 decks)

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