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A Level Biology > 4.1 Biodiversity, Evolution And Disease > Flashcards

4.1 Biodiversity, Evolution And Disease Flashcards

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1
Q

Describe the features of fungi

A

•Live under the skin

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2
Q

Describe the features of bacteria

A
  • reproduce rapidly

* cause disease by damaging cells/releasing waste products/toxins

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3
Q

Describe the features of viruses

A

•Invade cells + take over genetic machinery + other organelles of cell
E.g HIV

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4
Q

Describe the features of protoctista

A

•Enter host cells + feed on contents as they grow

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5
Q

What is a pathogen

A

An organism that causes disease

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6
Q

What are the different ways diseases are transmitted?

A

Vectors

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7
Q

Describe how diseases are transmitted through vectors

A
  • Organisms e.g insects that transmit parasites from one host to another
  • food air water
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8
Q

What are the passive (physical) defences plants have against pathogens?

A
  • Cellulose cell wall - contains chemical defences
  • Bark - chemical defences
  • Callose deposition
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9
Q

What is callose?

A

A large polysaccharide that blocks the flow in the sieve tube, prevents pathogen spreading around plant.

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10
Q

Name the different primary defences against pathogens in animals

A
  • Skin
  • Blood clotting + skin repair
  • Mucous membranes
  • Coughing + sneezing
  • Inflammation
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11
Q

How does the skin act as a primary defence?

A

Epidermis (outer layer of skin) contains dead skin cells which undergo keratinisation: they dry out and are replaced by the protein keratin.
The keratinised layer of dead cells acts as an effective barrier to pathogens.

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12
Q

How does blood clotting and skin repair act as a primary defence?

A

Platelets release clotting factors that cause an enzyme cascade that forms a clot and eventually a scab.

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13
Q

How do mucous membranes act as a primary defence?

A

Protects surfaces at risk of infection.

Most mucous swallowed and pathogens killed by acidity of stomach.

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14
Q

How does coughing and sneezing act as a primary defence?

A

respond to irritant caused by microbes/toxins by attempting to expel them.

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15
Q

How does inflammation act as a primary defence?

A
  • Histamine is released and causes vasodilation
  • white blood cells leave blood and enter tissue fluid
  • opsonins released and attach to neutrophil
  • engulfs the pathogen in phagosome (capsule)
  • lysosomes then destroys the bacteria
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16
Q

What is a phagocyte

A

The first line of secondary defence, specialised cells in the blood and tissue fluid engulf + digest the pathogens

17
Q

What are the 2 types of phagocytes

A

Neutrophils:
Nucleus is split into multiple parts + connected together so it’s more flexible

Macrophages:
Do not move quickly
Link with immune defence
Stores the antigens of pathogens

18
Q

How do phagocytes engulf pathogens

A
  • macrophages or neutrophils recognise invading bacteria as pathogens
  • cell membrane of macrophage/neutrophil fuses around a single bacterium, trapping it inside a cellular compartment called phagosome
  • Opsonins (non-specific antibodies) released
  • Once pathogen is inside phagosome capsule lysosomes destroy bacteria and keep useful parts, expelling the rest.
19
Q

What is a T helper cell?

A

cells that release signalling molecules to stimulate immune response

20
Q

What is a T killer cell?

A

Cells that attack or destroy our own body cells that are infected by pathogen

21
Q

What is a T/B memory cell?

A

Cells that remain in the blood for a long time, providing long-term immunity

22
Q

What is a T regulator cell?

A

Cells that are involved with inhibiting or ending the immune response

23
Q

What are antibodies?

A

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

24
Q

What are the 4 main stages in the immune responce

A
  • phagocytes engulf pathogens
  • phagocytes activate T lymphocytes
  • t lymphocytes activate b lymphocytes, which divide into plasma cells
  • plasma cells make more antibodies to a specific antigen
25
Q

Describe the primary responce

A
  • When pathogen enters body for first time, antigens on its surface activate the immune system
  • slow as not many B lymphocytes that can make the antibody needed to bind to it
  • after being exposed to the antigen, T+Blymphocytes produce memory cells
  • memory TL remember antigen
  • mBL remember antibody
26
Q

Describe the secondary responce

A

-quicker stronger response

27
Q

What is clonal selection

A

increase in number of cells by mitotic cell divison

28
Q

Describe opsonisation

A
  • antibody molecule has 2 binding sites
  • it also has an end that can stimulate phagocytes
    opsonisation: the end of the antibody stimulates phagocytosis
29
Q

Describe agglutination

A
  • antibodies bind to antigens on surface of several pathogens, clumping them together
  • macrophages can recognise and easily destroy pathogen by phagocytosis
30
Q

Describe neutralisation

A

-antibodies can bind to antigens on pathogen’s membrane and prevent it from attaching+entering host cells

31
Q

Natural + active

A

getting ill. white blood cells fight infection and you become immune

32
Q

Natural + passive

A

through placenta through breast feeding

33
Q

Artificial + active

A

vaccines

34
Q

Artificial + passive

A

injection of white blood cells

35
Q

How are diseases transported through spores?

A

Spores are cells that some organisms use 2reproduce asexually, including some protoctista and all fungi

36
Q

Diseases protoctist cause:

A
  • malaria

- potato/tomato late blight

37
Q

Diseases fungus cause:

A
  • black sigatoka (bananas)
  • ringworm (cattle)
  • athlete’s foot
38
Q

Diseases virus cause:

A
  • HIV/AIDS
  • Influenza
  • tobacco mosaic virus (plants)
39
Q

Diseases bacterium cause:

A
  • Tuberculosis
  • bacterial meningitis
  • ring rot (potats, tomats)

A Level Biology (18 decks)

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