Communicable diseases Flashcards Preview

Paper 2 Biological diversity > Communicable diseases > Flashcards

Flashcards in Communicable diseases Deck (25)
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1
Q

Disease definition

A

Condition that affects the normal functioning of an organism

2
Q

Types of pathogens

A

Bacteria
Viruses
Fungi
Protoctists

3
Q

Classification of bacteria

A
  • Shapes (bacillus, coccus, vibrio)

- Cell walls (gram positive and gram negative)

4
Q

Bacterial diseases

A

Ring rot
Bacterial meningitis
TB

5
Q

Viral diseases

A

AIDS
Influenza
Tobacco mosaic virus (TMV)

6
Q

Fungal diseases

A

Black sigatoka
Ringworm
Athlete’s foot

7
Q

Protictist diseases

A

Potato blight

Malaria

8
Q

Viruses mode of damaging host tissue

A
  • they affect the cell metabolism
  • viral genetic material enters the host DNA
  • virus uses the new cell to replicate new viruses which then burst out of the cell and destroying it
  • spread out to infect neighbouring cells
9
Q

Protoctista mode of damaging host tissue

A
  • break cells but don’t take over the genetic material

- digest and use the cell contents to reproduce

10
Q

Fungi mode of damaging host tissue

A
  • digest living cells and destroy them

- produce toxins which affect the cell

11
Q

Bacteria mode of damaging host tissue

A
  • produce toxins that damage and poison the cell

- toxins can damage the cell membrane, inactivate enzymes, interfere with host’s genetic material

12
Q

Types of transmission

A

Direct and indirect

13
Q

Indirect transmission (animals)

A
  • fomites (inanimate objects such as bedding, socks, cosmetic brushes)
  • droplet infection (saliva or mucus)
  • vectors (such as flies, water)
14
Q

Direct transmission (animals)

A
  • direct contact (kissing, body fluids contact, skin to skin contact, microorganisms from faeces)
  • ingestion (through food or drink)
  • inoculation (break in the skin, puncture wound, needles, animal bite)
15
Q

Indirect transmission (plants)

A
  • soil contamination

- vectors (wind, water, animals, humans)

16
Q

Direct transmission (plants)

A

direct contact of a healthy plant with a diseased plant

17
Q

Factors affecting communicable diseases (animals)

A
  • overcrowding
  • poor nutrition
  • compromised immune system
  • climate change
  • culture and infrastructure
18
Q

Factors affecting communicable diseases (plants)

A
  • planting species susceptible to disease
  • poor mineral nutrition
  • poor water availability
  • damp, warm conditions increase spread of disease
  • climate change
19
Q

Plant defences against pathogens

A
  • physical

- chemical

20
Q

Mechanism of recognition of attack in plants neurons

A
  • Pathogenic enzymes break down cell membrane and the products are recognised by the receptors of the cell
  • Signalling molecules alert nucleus to attack
  • Polysaccharides (callose and lignin) are produced to strengthen the cell walls
  • Defensive chemicals signal the other cells before they are attacked
  • Some defensive molecules attack the pathogen directly
21
Q

Physical defences

A
  • Callose is synthesised and deposited b/n cell walls in order to prevent the pathogens from entering the neighbouring cells
  • lignin and callose are deposited to form a barrier against infection
  • callose deposits between sieve plates
22
Q

Chemical defences

A
  • insect repellents
  • insecticides (pyrethrins)
  • antibacterial compounds including antibiotics (phenols, defensives, lysosomes)
  • antifungal compounds (phenols, caffeine, saponins, chitanases)
  • general toxins (chemicals can be broken down to form cyanide compounds which are toxic)
  • anti-oomycetes (glucanases)
23
Q

Non-specific animal defences against pathogens

A
  • skin (skin flora with with healthy microorganisms)
  • mucus membrane lining on airways and body tracts
  • lysozyme in tears and urine and acid in stomach
  • repulsive reflexes such as coughing, sneezing, vomiting, and diarrhoea
  • blood clotting and wound repair
  • inflammatory responses
  • fever
  • phagocytosis
24
Q

Inflammatory response

A

Mast cells are activated in damaged tissue and release chemicals:

  • histamines make blood vessels dilate, causing redness and they become more leaky, so blood plasma is forced out and forms tissue fluid, causing swelling and pain
  • cytokines attract white blood cells (phagocytes) to the site so they can undergo phagocytosis
25
Q

Blood clotting

A
  • Damaged tissue leads to platelets being activated, which release THROMBOPLASTIN
  • THROMBOPLASTIN + CA2+ ions catalyse the formation of THROMBIN from PROTHROMBIN
  • THROMBIN catalyses the production of FIBRIN from fibrinogen
  • Fribrin + collagen fibres forms a mesh to forms a blood clot