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OCR AS LEVEL BIOLOGY > Diseases, Communication and Immune System > Flashcards

Diseases, Communication and Immune System Flashcards

1
Q

Definition of pathogen

A

An organism which lives on or inside another organism, and causes a disease

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2
Q

Definition of toxin

A

A substance which is produced by a living organism, typically a pathogen, which is poisonous to the cells of another organism

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3
Q

Definition of a vector

A

An animal which carries a pathogen in its body and transmits it, but it is not the main host of the pathogen.

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4
Q

Symptoms of a flowering plant infected with Tobacco Mosaic Virus

A 
Leaf tissue is mottled, with brown marks
Fruit is slower to ripen
Leaf tissues may become yellow and die
Leaves curl at the edges
Reduced seed/ fruit yield
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5
Q

What is HIV/AIDS and how does it cause disease

A

It is a virus

The pathogen infiltrates and lives inside T-helper cells, gradually weakening the immune system

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6
Q

What is Bacterial Meningitis and how does it cause disease

A

Bacterium
The pathogen replicates in the meninges of the brain, causing swelling; can spread into the blood where it leads to septicaemia

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7
Q

What is Athlete’s foot and how does it cause disease

A

Fungus

The pathogen lives on and digests damp skin around the toes, causing a red rash

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8
Q

What is Malaria and how does it cause disease

A

Protoctist

The pathogen invades red blood cells and liver, causing fever and vomiting and weakening the body’s immune system.

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9
Q

How does HIV/AIDs spread

A

Direct (sexual) contact

Breaks in skin genitals

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10
Q

How does Ebola spread

A

Contact with bodily fluids including sexual contact

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11
Q

How can an injection cause diseases

A

Through contaminated needles

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12
Q

How does ingestion cause diseases

A

Eating infected food

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13
Q

vectorborne transmission

A

Stagnant water-> (direct transmission): drinking water contaminated with faeces which will lead to cholera
Bites from insects etc- a mosquito bite could lead to Malaria if the mosquito carries the pathogen

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14
Q

Fomites transmission

A

Particles of dead/skin/ hair in bedding- lead to Athlete’s foot

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15
Q

Airborne transmission

A

Through coughing and sneezing, mucus droplets are spread in air
This can lead to influenza

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16
Q

Examples of direct transmission

A

Ingestion
Direct contact - both sexual and skin
Exposed cuts
Injection

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17
Q

Examples of indirect transmission

A

Vector borne
Airborne
Fomites

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18
Q

Why might climate change increase the transmission of a disease

A

Increasing global temperatures mean that some vectors, such as Zika-virus-carrying mosquitoes or tsetse flies, have a broader range in which they can live and breed, making transmission more likely.

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19
Q

Why might living in a refugee camp increase the transmission of a disease

A

Refugee camps are typically overcrowded, which makes transmission of airborne diseases more likely, since people are often in close contact. In addition, they often have poor sanitation- this means that diseases spread by contact with contaminated food or water are more likely.

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20
Q

Plant primary defences

A

Bark on stem provides stability
waxy cuticle on the upper surface on the leaves waterproofs it

However, some pathogens do still manage to access the plant. Infected parts of the plant can be sealed off using a polysaccharide known as callose, which closes the plasmodesmata (gaps) between cells and also prevent movement throguh the phloem by blocking the sieve end plates.

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21
Q

Chemicals plants use as defence mechanisms, and how does it work

A

Saponins: chemicals with detergent-like properties that disrupt the cell membranes of fungal cells

Phytoalexins: disrupts the metabolism and cellular structure of fungi and bacteria.

Caffeine: inhibits enzymes in the nervous systems of insects, causing paralysis.

Other ex: cyanide, gossypol, pyrethrins, chitinase

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22
Q

main primary defences the human body uses to prevent the entry of pathogens

A

Skin tissue is tough and difficult to break through
Blood clotting rapidly blocks a point of entry for pathogens
Mucus in the throat traps pathogens, which are brushed upwards by the cilia and swallowed
Coughing and sneezing may remove potential pathogens from the airways
Inflammation restricts the movement of pathogens from the airways.
Lysozymes (digestive enzymes) are produc3d in tears and urine.
Stomach acid has a low pH which kills or inactivates many pathogens.

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23
Q

Why do histamines increase the temperature around a site of infection

A

Makes it more difficult for pathogens to reproduce, since human pathogens typically have a preferred temperature that’s the same as core body temperature

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24
Q

Process of blood clotting

A

Platelets are activated by damaged tissue
Thromboplastin is released into the area around the wound
The enzyme causes prothrombin to be converted into thrombin
This compound converts the precursor protein fibrinogen into its active form
Fibrin produces a layer of fibres over the wound, stopping the movement of pathogens.
New skin is created beneath the protein mesh.

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25
How does neutrophils destroy pathogens
Neutrophils engulf a pathogen by surrounding it with the neutrophil membrane, and the ‘budding off’ part of the membrane to form a vesicle. Then they digest the pathogen using enzymes called lysozymes.
26
When does neutrophils destroy pathogens
Occurs in the blood or in an infected tissue once an infection has been recognised.
27
How does phagocytes find pathogens and damaged cells
Pathogen and dead or damaged cells produce waste products that act as attractants to the phagocytes, the phagocyte moves towards the pathogen or cell and uses receptors on its cell-surface membrane to attach to the surface of the pathogen or cell. Pathogens also recognise and digest cells which have been marked by opsonins- a broad range of marker molecules which include antibodies.
28
How does a phagocyte engulf and destroy a pathogen
When the phagocyte engulfs the pathogen, the pathogen is then contained within a vesicle called a phagosome. Lysosomes within the phagocyte then move towards and fuse with the vesicle, releasing lysozymes into the phagosome. The lysozymes hydrolyse the cell walls of the pathogens, destroying the pathogen.
29
What happens to the breakdown products of the pathogen
The soluble breakdown products are absorbed into the cytoplasm of the phagocyte.
30
Where does a Plasma cell mature and its function
Bone marrow | Produces huge numbers of antibodies which trap pathogens and encourage phagocytosis.
31
Where does B-memory cell mature and its function
Bone marrow | Stays in immune system for years, and creates plasma cells when exposed to a specific antigen.
32
Where T-helper cell mature and its function
Thymus gland Had receptors which bind to antigens on antigen-presenting cells; produces interleukins which signal to various other immune cells.
33
Where does a T-regulator cell mature and its function
thymus gland | Able to regulate the immune system and suppress it to stop autoimmune responses
34
Why are interleukins described as immune response modulators
Interleukins are chemicals which signal between different white blood cells, and affect the immune response. For example, the interleukins produced by T-helper cells encourage the creation of T-killer cells, and make both phagocytes and plasma cells more active. However, interleukins are also involved in the suppression of the immune response by T-regulatory cells.
35
How do T-killer cells kill pathogens
Release perforin that increases the permeability of the pathogen’s cell-surface membrane by making small holes through the membrane. Substances freely leave the cell and the cell dies.
36
How do plasma cells form
The B lymphocyte divides rapidly, producing different cells, including many cloned B-plasma cells which in turn make antibodies.
37
What do the interleukins do and how are they produced
Cause T cells to divide and specialise creating cells such as T killer/cytotoxic cells T helper cells with an antigen recognition complex attaches to the B cell, activating the B cell by producing interleukins.
38
Why can some individuals experience a secondary immune response without experiencing any symptoms at all
B memory cells already exist which can produce the correct antibody to target the pathogen’s antigen. When these cells recognise the pathogen, they divide rapidly to form plasma cells, which create huge numbers of antibodies, overwhelming and destroying the pathogen. This can occur quickly enough that the pathogen has not had time to cause any significant symptoms.
39
What features of antibodies makes agglutination possible
Two antigen binding sites. This means that antibodies can cross link to the antigens of two pathogens, holding the pathogens together and impeding movement.
40
Ways antibodies result in the destruction of a pathogen
The antibodies cause agglutination, so pathogens form clumps which phagocytes can more easily locate. Antibodies act as markers to stimulate phagocytosis of the pathogens they are attached to.
41
Definition of opsinin
A molecule that labels a pathogen, making it easier for phagocytes to recognise and engulf it.
42
Definition of variable region
Part of the antibody that is targeted to bind to a specific antigen.
43
Definition of antitoxin
A molecule that binds to a harmful substance, reducing or eliminating its effect.
44
Definition of immunoglobulins
Another term for antibodies; glycoprotein molecules which are crucial to specific immunity
45
Definition of light chain
One of the two shorter peptides that make up an antibody.
46
Natural activity immunity- antibody source
Stimulates antibody production in own system
47
Natural active immunity- memory cells produced
Memory cells formed therefore, long-lived
48
Natural active immunity- example
Infected with any disease that re-encounters
49
Passive immunity- antibody source
Introduces antibodies from an outside source
50
Passive immunity- memory cells produced
No memory cells formed; therefore, short-lived
51
Passive immunity- example
Anti-venom / through placenta to foetus
52
Artificial active immunity-antibody source
Stimulates antibody production in own system
53
Artificial active immunity-memory cells produced
Memory cells formed; therefore, long-luved
54
Artificial active immunity-example
Vaccination to introduce harmless form of disease
55
How molecules in cell-surface membrane play an important role in immunity
Cell-surface membrane molecules act as recognition sites so lymphocytes can distinguish between body and foreign cells. The proteins have a highly variable specific 3D structure, allowing many cells, pathogens and toxins to be distinguished from each other.
56
How does neutrophils destroy pathogens
Neutrophils engulf a pathogen by surrounding it with the neutrophil membrane, and the ‘budding off’ part of the membrane to form a vesicle. Then they digest the pathogen using enzymes called lysozymes.
57
When does neutrophils destroy pathogens
Occurs in the blood or in an infected tissue once an infection has been recognised.
58
How does phagocytes find pathogens and damaged cells
Pathogen and dead or damaged cells produce waste products that act as attractants to the phagocytes, the phagocyte moves towards the pathogen or cell and uses receptors on its cell-surface membrane to attach to the surface of the pathogen or cell. Pathogens also recognise and digest cells which have been marked by opsonins- a broad range of marker molecules which include antibodies.
59
How does a phagocyte engulf and destroy a pathogen
When the phagocyte engulfs the pathogen, the pathogen is then contained within a vesicle called a phagosome. Lysosomes within the phagocyte then move towards and fuse with the vesicle, releasing lysozymes into the phagosome. The lysozymes hydrolyse the cell walls of the pathogens, destroying the pathogen.
60
What happens to the breakdown products of the pathogen
The soluble breakdown products are absorbed into the cytoplasm of the phagocyte.
61
Where does a Plasma cell mature and its function
Bone marrow | Produces huge numbers of antibodies which trap pathogens and encourage phagocytosis.
62
Where does B-memory cell mature and its function
Bone marrow | Stays in immune system for years, and creates plasma cells when exposed to a specific antigen.
63
Where T-helper cell mature and its function
Thymus gland Had receptors which bind to antigens on antigen-presenting cells; produces interleukins which signal to various other immune cells.
64
Where does a T-regulator cell mature and its function
thymus gland | Able to regulate the immune system and suppress it to stop autoimmune responses
65
Why are interleukins described as immune response modulators
Interleukins are chemicals which signal between different white blood cells, and affect the immune response. For example, the interleukins produced by T-helper cells encourage the creation of T-killer cells, and make both phagocytes and plasma cells more active. However, interleukins are also involved in the suppression of the immune response by T-regulatory cells.
66
How do T-killer cells kill pathogens
Release perforin that increases the permeability of the pathogen’s cell-surface membrane by making small holes through the membrane. Substances freely leave the cell and the cell dies.
67
How do plasma cells form
The B lymphocyte divides rapidly, producing different cells, including many cloned B-plasma cells which in turn make antibodies.
68
What do the interleukins do and how are they produced
Cause T cells to divide and specialise creating cells such as T killer/cytotoxic cells T helper cells with an antigen recognition complex attaches to the B cell, activating the B cell by producing interleukins.
69
Why can some individuals experience a secondary immune response without experiencing any symptoms at all
B memory cells already exist which can produce the correct antibody to target the pathogen’s antigen. When these cells recognise the pathogen, they divide rapidly to form plasma cells, which create huge numbers of antibodies, overwhelming and destroying the pathogen. This can occur quickly enough that the pathogen has not had time to cause any significant symptoms.
70
What features of antibodies makes agglutination possible
Two antigen binding sites. This means that antibodies can cross link to the antigens of two pathogens, holding the pathogens together and impeding movement.
71
Ways antibodies result in the destruction of a pathogen
The antibodies cause agglutination, so pathogens form clumps which phagocytes can more easily locate. Antibodies act as markers to stimulate phagocytosis of the pathogens they are attached to.
72
Definition of opsinin
A molecule that labels a pathogen, making it easier for phagocytes to recognise and engulf it.
73
Definition of variable region
Part of the antibody that is targeted to bind to a specific antigen.
74
Definition of antitoxin
A molecule that binds to a harmful substance, reducing or eliminating its effect.
75
Definition of immunoglobulins
Another term for antibodies; glycoprotein molecules which are crucial to specific immunity
76
Definition of light chain
One of the two shorter peptides that make up an antibody.
77
Natural activity immunity- antibody source
Stimulates antibody production in own system
78
Natural active immunity- memory cells produced
Memory cells formed therefore, long-lived
79
Natural active immunity- example
Infected with any disease that re-encounters
80
Passive immunity- antibody source
Introduces antibodies from an outside source
81
Passive immunity- memory cells produced
No memory cells formed; therefore, short-lived
82
Passive immunity- example
Anti-venom / through placenta to foetus
83
Artificial active immunity-antibody source
Stimulates antibody production in own system
84
Artificial active immunity-memory cells produced
Memory cells formed; therefore, long-luved
85
Artificial active immunity-example
Vaccination to introduce harmless form of disease
86
How molecules in cell-surface membrane play an important role in immunity
Cell-surface membrane molecules act as recognition sites so lymphocytes can distinguish between body and foreign cells. The proteins have a highly variable specific 3D structure, allowing many cells, pathogens and toxins to be distinguished from each other.

OCR AS LEVEL BIOLOGY (22 decks)

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