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A Level Biology OCR A > 4.1.1 > Flashcards

4.1.1 Flashcards

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1
Q

What is a pathogen?

A

A microorganism that causes disease.

Pathogens can be bacteria, fungi, viruses, or protoctists.

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2
Q

What is the host in the context of pathogens?

A

The organism in which pathogens live.

Pathogens take nutrition from their host and cause damage in the process.

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3
Q

What are bacteria classified as?

A

Kingdom prokaryotae.

Bacteria have smaller cells than eukaryotic cells and can reproduce rapidly.

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4
Q

How quickly can some bacteria reproduce under the right conditions?

A

Every 20 minutes.

This rapid reproduction can lead to significant damage in the host.

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5
Q

What damage can bacteria cause to plants?

A

Blackening and death of vascular tissues.

Bacteria can also damage cells and release toxins.

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6
Q

What is a common fungal infection in animals?

A

Infections where the fungus lives in the skin.

The fungus’s hyphae grow under the skin surface, causing irritation.

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7
Q

What do fungi release to digest surrounding tissue in plants?

A

Extracellular enzymes, such as cellulases.

This leads to decay of plant tissues.

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8
Q

What is the mode of action of viruses?

A

Invade cells and take over the cell’s genetic machinery.

They cause the cell to manufacture more copies of the virus.

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9
Q

What is an example of a disease caused by a protoctist?

A

Malaria.

The malarial parasite Plasmodium feeds on the haemoglobin inside red blood cells.

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10
Q

What bacterium causes tuberculosis?

A

Mycobacterium tuberculosis and M. bovis.

This disease affects various body parts, primarily the lungs.

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11
Q

What bacteria cause bacterial meningitis?

A

Neisseria meningitidis or Streptococcus pneumonia.

It infects the membranes surrounding the brain and spinal cord.

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12
Q

What bacterium causes ring rot in plants?

A

Clavibacter michiganensis susp. Sepedonicus.

This leads to decay in potato tubers and wilting of leaves.

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13
Q

What virus causes HIV/AIDs?

A

Human immunodeficiency virus.

It attacks cells in the immune system.

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14
Q

What family do the viruses that cause influenza belong to?

A

Orthomyxoviridae.

They primarily attack the respiratory system.

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15
Q

What fungus causes black sigatoka in banana plants?

A

Mycosphaerella fijiensis.

It causes leaf spots and reduces yield.

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16
Q

What is the primary cause of blight in tomatoes and potatoes?

A

Phytophthora infestans.

It affects the leaves and tubers.

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17
Q

What fungus causes ringworm in cattle?

A

Trichophyton verrucosum.

It erupts through the skin, causing a rash.

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18
Q

What is athlete’s foot caused by?

A

Trichophyton rubrum.

It grows under the skin on the feet.

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19
Q

What protoctists cause malaria?

A

Plasmodium falciparum, P. vivax, P. ovale, or P. malariae.

It can lead to severe symptoms like headache and fever.

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20
Q

What is direct transmission?

A

Passing a pathogen from host to new host, with no intermediary.

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21
Q

What is indirect transmission?

A

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

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22
Q

What is a vector?

A

An organism that carries a pathogen from one host to another.

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23
Q

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

A
  • Travel from one host to another
  • Entering the host’s tissues
  • Reproducing
  • Leaving the host’s tissues.
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24
Q

What factors affect the transmission of pathogens?

A
  • Direct physical contact
  • Faecal-oral transmission
  • Droplet infection
  • Transmission by spores.
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25
How can direct physical contact transmission be reduced?
By better hygiene practices. ## Footnote This includes washing hands and cleaning surfaces.
26
What is faecal-oral transmission?
Transmission usually by eating food or drinking water contaminated with the pathogen.
27
What is droplet infection?
Transmission in which the pathogen is carried in tiny water droplets in the air.
28
What is an example of a disease transmitted by spores?
Anthrax or tetanus. ## Footnote Spores are a resistant stage of the pathogen.
29
What social factors affect pathogen transmission?
* Overcrowding * Poor ventilation * Poor health * Poor diet * Homelessness.
30
Is tuberculosis easily transmitted?
No, it often requires prolonged close proximity to be transmitted.
31
What is an example of a vector in malaria transmission?
Female Anopheles mosquito.
32
What is the lifecycle of Plasmodium in malaria?
* Mosquito sucks blood from infected person * Plasmodium develops and migrates to mosquito's salivary glands * Mosquito bites uninfected person * Plasmodium migrates to liver and blood of new host.
33
How can plant pathogens be spread?
By direct and indirect means, including soil and insect vectors.
34
What are passive defences in plants?
Defences present before infection to prevent entry and spread of pathogens.
35
What are some examples of physical defences in plants?
* Cellulose cell wall * Lignin thickening * Waxy cuticles * Bark * Stomatal closure. * Callose deposition. * Tylose formation.
36
What are chemical defences in plants?
Chemicals that have anti-pathogenic properties, such as terpenoids and phenols.
37
What are active defences in plants?
Defensive responses triggered by pathogen detection, including thickening cell walls and producing defensive chemicals.
38
What are terpenoids?
Essential oils with antibacterial and antifungal properties.
39
What are defensive proteins in plants?
Small cysteine-rich proteins with broad antimicrobial activity.
40
What are hydrolytic enzymes?
Enzymes that break down components of pathogens, such as chitinases and lysozymes.
41
What role do tannins play in plant defence?
Inhibit attack by insects and deactivate digestive enzymes. ## Footnote High amounts can prevent insect growth.
42
What is necrosis in plants?
Deliberate cell suicide to limit pathogen access to nutrients.
43
What is canker in plants?
A sunken necrotic lesion.
44
What is necrosis?
Deliberate cell suicide to limit pathogen access ## Footnote It involves sacrificing some cells surrounding an infection to prevent its spread.
45
What is a canker?
A sunken necrotic lesion in woody tissue causing death of cambium tissue ## Footnote Typically found on the main stem or branch.
46
Define inflammation.
Swelling and redness of tissue caused by infection ## Footnote It may also involve heat and pain.
47
What are primary defences?
Mechanisms that prevent pathogens from entering the body ## Footnote They are non-specific and act against any pathogen.
48
What is the outer layer of the skin called?
Epidermis ## Footnote Composed of layers of keratinocytes.
49
What is keratinisation?
The process where keratinocytes migrate out, dry out, and become keratinized ## Footnote Takes about 30 days.
50
What happens during blood clotting?
Platelets form a plug and fibrin creates a mesh that seals the wound ## Footnote Involves activation of clotting factors and thrombin.
51
What are mucous membranes?
Epithelial tissues covered by mucus that protect areas prone to infection ## Footnote Found in airways, lungs, and digestive systems.
52
What is the role of goblet cells?
Secrete mucus in the epithelial layer of mucous membranes ## Footnote They help trap pathogens.
53
What do mast cells release during inflammation?
Histamine ## Footnote It causes vasodilation and increases permeability of capillary walls.
54
What is an antigen-presenting cell?
A cell that displays antigens on its plasma membrane for recognition by the immune system ## Footnote Helps initiate specific immune responses.
55
What is clonal selection?
Selection of specific B or T cells that recognize a specific antigen ## Footnote It leads to an immune response.
56
What are cytokines?
Hormone-like molecules used in cell signaling to stimulate the immune response ## Footnote They play a role in activating immune cells.
57
What is the primary function of neutrophils?
Engulf and digest foreign matter ## Footnote They are a type of phagocyte.
58
Define opsonins.
Proteins that bind to antigens on pathogens to enhance phagocytosis ## Footnote They play a role in the immune response.
59
What is the role of macrophages?
Engulf pathogens and present antigens to initiate specific immune responses ## Footnote They mature from monocytes in tissues.
60
What do T helper cells do?
Release cytokines to stimulate B cells and phagocytosis ## Footnote They play a crucial role in the immune response.
61
What are T killer cells responsible for?
Attacking and destroying infected body cells ## Footnote They are vital in combating infections.
62
What is active immunity?
Immunity that develops after exposure to an antigen ## Footnote It involves the production of memory cells.
63
What is clonal expansion?
Increase in the number of specific lymphocytes through mitosis ## Footnote It is crucial for an effective immune response.
64
What occurs during the immune response activation?
Detection of antigens by specific B and T lymphocytes ## Footnote This triggers clonal selection.
65
What is an autoimmune disease?
When the immune system attacks the body's own cells ## Footnote It can arise from genetic and environmental factors.
66
What is the function of T memory cells?
Provide long-term immunity by remaining in the blood ## Footnote They enable a quicker response to future infections.
67
What signals the phagocytes to increase activity?
Cytokines released by macrophages and T cells ## Footnote These signaling molecules enhance the immune response.
68
What structures are specialized in plasma cells?
Numerous organelles for protein synthesis and secretion ## Footnote Includes ribosomes, rough ER, Golgi apparatus, and mitochondria.
69
What occurs in autoimmune diseases?
The immune system attacks a part of the body. ## Footnote Autoimmune diseases arise when antibodies attack our own antigens.
70
What are the potential causes of autoimmune diseases?
Unknown, but include genetic and environmental factors. ## Footnote Specific causes are still under research.
71
What is arthritis?
A painful inflammation of a joint caused by antibodies attacking the membranes around the joint. ## Footnote The exact cause of arthritis remains uncertain.
72
What is lupus?
A disease that can affect any part of the body, causing swelling and pain, associated with antibodies attacking proteins in the cell nucleus. ## Footnote It is a systemic autoimmune condition.
73
Define agglutinins.
Antibodies that cause pathogens to stick together.
74
Define antitoxins.
Antibodies that render toxins harmless.
75
Define opsonins.
Antibodies that make it easier for phagocytes to engulf the pathogen.
76
What is the primary immune response?
The initial response caused by a first infection.
77
What is the secondary immune response?
A more rapid and vigorous response caused by a second or subsequent infection by the same pathogen.
78
What are antigens?
Molecules that can stimulate an immune response, usually proteins or glycoproteins in the plasma membrane of pathogens.
79
What are antibodies?
Immunoglobulins produced by plasma cells in the immune system in response to an infection.
80
Describe the structure of an antibody.
Y-shaped with two distinct regions and consists of four polypeptide chains.
81
How do antibodies work?
By attaching to antigens on a pathogen, with three main groups: opsonins, agglutinins, and anti-toxins.
82
What is the function of opsonins?
Bind to antigens on pathogens, acting as binding sites for phagocytic cells.
83
What is the process of neutralization in immunity?
When opsonins bind to antigens, rendering them useless, preventing pathogen entry into host cells.
84
What is the role of agglutinins?
Crosslink pathogens, clumping them together to impede their function and facilitate phagocytosis.
85
What do anti-toxins do?
Bind to toxic molecules released by pathogenic cells, rendering them harmless.
86
What happens during the primary immune response?
Antibodies are produced after a few days of detecting an infecting agent.
87
What is the role of memory cells in the immune response?
Allow for a quicker and more robust antibody production during a secondary infection.
88
Define epidemic.
A rapid spread of disease through a high proportion of the population.
89
What is vaccination?
A way of stimulating an immune response to achieve immunity.
90
List the forms of antigenic material used in vaccines.
* Whole, live microorganisms * Harmless or attenuated versions of pathogens * Dead pathogens * Preparations of antigens * Toxoids
91
What is herd vaccination?
Vaccination to provide immunity to all or almost all of the population at risk.
92
What is ring vaccination?
Vaccinating all people in the immediate vicinity of a reported new case of a disease.
93
What happens once a disease is eradicated?
Routine vaccination programs can be relaxed.
94
What is the significance of genetic mutations in pathogens?
They can change antigens, making memory cells ineffective against new strains.
95
What is influenza?
A viral disease particularly lethal to those over 65 and with respiratory conditions.
96
What was the impact of the 1918 flu epidemic?
Killed at least 40 million people worldwide.
97
What is the current UK vaccination program for influenza?
Immunises all individuals over 65 and those at risk for other reasons.
98
What is the role of annual research in influenza vaccination?
To determine which strains are most likely to spread each year.
99
Fill in the blank: The strains of flu used in immunization programs _______.
[change each year].

A Level Biology OCR A (1 decks)

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