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AS Biology > 4.1.1 > Flashcards

4.1.1 Flashcards

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1
Q

Give an example of a bacterial plant disease

A

Ring rot

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2
Q

Give an example of a viral plant disease

A

TMV

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3
Q

Give 2 examples of fungal plant diseases

A

Potato blight and black sigatoka

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4
Q

Give two examples of bacterial diseases in animals

A

Bacterial meningitis and tuberculosis

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5
Q

Give two examples of viral diseases in animals

A

HIV and Influenza

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6
Q

Give an example of an animal disease caused by a protist

A

Malaria

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7
Q

Give two examples of fungal diseases in animals

A

Ring worm and athlete’s foot

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8
Q

What are the types of direct transmission of pathogens between animals?

A

Direct contact, inoculation, ingestion

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9
Q

Give examples of direct contact

A
  • Kissing or any contact with the body fluids of another person
  • Direct skin-to-skin contact
  • Microorganisms from faeces transmitted on the hands
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10
Q

Give examples of inoculation

A
  • Through a break in the skin
  • From an animal bite
  • Through a picture wound or through sharing needles
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11
Q

Give an example of ingestion

A

Taking in contaminated food or drink, or transferring pathogens to the mouth from the hands

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12
Q

What are the types of indirect transmission?

A
  • Fomites
  • Droplet infection
  • Vectors
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13
Q

What is a fomite?

A

An inanimate object that transfers pathogens

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14
Q

What is droplet infection?

A

When an infected individual talks, coughs or sneezes, the droplets of saliva and mucus may contain pathogens, which infect healthy individuals

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15
Q

What are vectors?

A

A vector is something that transmits communicable pathogens from one host to another

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16
Q

What factors affect the transmission of communicable diseases

A
  • Overcrowded living and working conditions
  • Poor nutrition
  • A compromised immune system
  • Poor disposal of waste
  • Climate change
  • Culture and infrastructure
  • Socioeconomic factors
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17
Q

What is the main physical defence of plants?

A

Callose

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18
Q

Describe the effect of callose

A
  • It is synthesised and deposited between the cell walls and the cell membrane in cells next to the infected cells. They prevent pathogens entering the plant cells around the site of infection
  • Callose blocks sieve plates in the phloem
  • Callose is deposited in the plasmodesmata between infected cells and their neighbours
19
Q

What are the chemical defences of plants?

A
  • Insect repellents
  • Insecticides
  • Antibacterial compounds
  • Antifungal compounds
  • Anti-oomycetes
  • Toxins
20
Q

What barriers exist to prevent the entry of pathogens in humans?

A

The skin, which contains a skin flora of microorganisms, and sebum, which inhibits growth of pathogens
Mucous membranes
Lysozymes in tears and urine

21
Q

Describe the process of blood clotting and wound repair

A

Skin is breached. Platelets reach the collagen in skin and release thromboplastin and thrombin

22
Q

What does thromboplastin do?

A

It catalyses the conversion of prothrombin into thrombin, in the presence of Ca+2. Thrombin then catalyses the conversion of fibrinogen to fibrin, which forms a clot

23
Q

What does serotonin do?

A

Makes the smooth muscle in the walls of the blood vessels contract, so they narrow and reduce the supply of blood to the area

24
Q

What is the inflammatory response?

A

A localised response to pathogens resulting in inflammation at the site of a wound

25
Q

What cells are activated in damaged tissue?

A

Mast cells

26
Q

What do mast cells release?

A

Cytokines and histamines

27
Q

What do histamines do?

A

Make the blood vessels dilate, causing localised heat and redness. Blood vessel walls also become more leaky so blood plasma is forced out

28
Q

What to cytokines do?

A

Attract white blood cells to the site.

29
Q

What are the stages of phagocytosis?

A
  • Pathogens produce chemicals that attract phagocytes
  • Phagocytes recognise the non-self antigens
  • Phagocyte engulfs the pathogen and encloses it in a vacuole called a phagosome
  • Phagosome combines with a lysosome to form a phagolysosome
  • Enzymes from the lysosome digest and destroy the pathogen
30
Q

What happens when a macrophage digests a pathogen?

A

It becomes an APC (antigen presenting cell)

31
Q

What are the two types of phagocytes?

A

Neutrophils and macrophages

32
Q

Which type of phagocyte has a multi-lobed nucleus?

A

Neutrophil

33
Q

What are opsonins?

A

Antibodies that tag antigens to make it easier for the macrophages to engulf the pathogens

34
Q

What are the two different types of lymphocytes?

A

T lymphocytes and B lymphocytes

35
Q

What happens at the start of the cell-mediated response?

A

Specific T helper cell binds to the APC. The T helper cell releases interleukins (a type of cytokine)

36
Q

What do the interleukins cause?

A

They cause the T helper cells to start dividing by mitosis and specialise into other types of cells?

37
Q

What cells do the T helper cells specialise into?

A

T memory cells, T killer cells, T regulatory cells

38
Q

What happens at the start of the humoral response?

A

A B cell with the specific antibody shape for the antigen binds to the antigen and becomes an APC. The B cell APC then binds to a T helper cell. This is clonal selection

39
Q

What is clonal expansion?

A

When the B cell divides by mitosis and specialises into other types of B cells. The main two types are B memory cells and B plasma cells

40
Q

What do the B plasma cells do?

A

They make even more B plasma cells, which produce antibodies specific to the antigen

41
Q

How are the heavy chains and light chains on antibodies linked?

A

By disulfide bridges

42
Q

How many antigens can each antibody bind to?

A

2

43
Q

What are the different functions of antibodies?

A
  • Act as agglutinins, sticking the pathogens together, making phagocytosis easier
  • Act as opsonins, tagging antigens
  • Act as antitoxins
  • Directly attack pathogens

AS Biology (9 decks)

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