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Biology IGCSE > Topic 10 > Flashcards

Topic 10 Flashcards

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1
Q

What is a microorganism

A

A very small living thing

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2
Q

What are pathogens

A

Microorganism that causes disease

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3
Q

Transmissable/communicable disease

A

Caused by a pathogen and can be passed from one host to another

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4
Q

4 types of pathogens

A

Viruses
Bacteria
Fungi
Protists

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5
Q

Ways in which pathogens are spread (7)

A
  • Contaminated food
  • Sharing needles
  • Contaminated surfaces
  • Sexually transmitted
  • Bloodily fluids
  • Airborne droplets
  • Animals
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6
Q

How can a pathogen be transmitted?

A

Direct contact
Indirect contact

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7
Q

Examples of direct contact

A

. Blood
. Bloodily fluids

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8
Q

Examples of indirect contact

A

. Contaminated surfaces
. Air
. Food
. Animals

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9
Q

The body’s primary defences (5)

A

Trying to prevent pathogens from entering the body
- Eyelashes
- Hair in the nose
- Skin
- Stomach
- Mucus

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10
Q

Examples of mechanical barriers for body

A

. Hair in the nose -> traps the pathogens in the air
. Skin -> mechanical physical barrier
-> If you damage the skin, platelets clot to seal wound

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11
Q

Example of chemical barriers in body

A

. Stomach -> contains HCL
-> kills any pathogens
. Mucus -> chemical cells in trachea and bronchi produce mucus
-> trap pathogens

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12
Q

How do pathogens cause harm?

A

1) They can reproduce and they can damage cells
2) Produce toxins
- When pathogens infect us, the WBCs fight pathogens

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13
Q

Phagocytosis

A
  • Engulf and digest pathogenical material
    . By phagocytes
    . They recognise ‘foreign’ pathogens and elngulf them
    . Not specific
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14
Q

Antigens

A
  • All pathogens have their own unique ‘markers’ on the cell membrane, antigens, which have specific shapes
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15
Q

Anti-body production

A
  • By lymphocytes
    1) Lymphocytes encounter ‘foreign’ antigens and will produce complimentary shaped proteins called antibodies
    2) Antibodies secreted by the lymphocytes bind to the antigens on pathogem
    -> They either destroy the pathogen of marks it for destruction by a phagocyte
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16
Q

Antibodies

A

. Proteins that bind to antigens leading to direct destruction of pathogens fro destruction by phagocytes

  • Made put of protein
  • Specific antibodies have complimentary shapes which fit specific antigens
17
Q

Preventing disease (6)

A

. Vaccination
. Treated sewage
. Waste disposal
. Good food hygiene
. Good hygiene
. Clean water supply

18
Q

Hygenic food preparation

A
  • Reduces spread of pathogens from work surfaces, chooping boards, etc, to food
19
Q

Good personal hygiene

A

Simple hygiene measures (eg. washing your hands after going to the toilet)

20
Q

Waste disposal

A

Not letting rubbish build up + safely dispose things such as bandages or needles

21
Q

Clean water supply

A

Access to clean, fresh water for drinking and cooking -> reduces spread of water-borne pathogens

22
Q

Sewage treatment

A

Good sewage systems prevent sewage from contaminating drinking water -> reduces spread of water-borne pathogens

23
Q

Cholera

A

. Caused by a bacterium
. Transmitted through spread of water

24
Q

How can we prevent the spread of water?

A

. Sewage treatment
. Clean water

25
Q

How does cholera cause these effects?

A

1) Bacterium produces a toxin
2) This causes secretion of chloride ions into the small intestine
3) The water potential in your small intestine decreases
4) Water moves into small intestine down water potential gradient (osmosis)
5) loss of water and mineral ions through diarrea

26
Q

Symptoms of cholera

A

. Dehydration
. Diarrhea
. Loss of mineral ions

27
Q

Passive immunity

A

Short- term defence against a pathogen by antibodies made by another individual

28
Q

Active immunity

A

Long-term defence against a pathogen by the production of antibodies and memory cells

29
Q

Passive immunity examples

A

. Babies have not yet fully developed
-> antibodies can pass from mother to feetus across placenta
. Breastfeeding

30
Q

Process of vaccination (active immunity)

A

1) Inject a weakened pathogen or inactive antigens from pathogen
2) This triggers an immune response and your lymphocytes produce antibodies against the pathogen
3) Some of the lymphocytes remain circulating the blood as memory cells for many years

31
Q

Active immunity

A

. Long-term
. Produces memory cells
. Production of antibodies
. Slower process
. Developed by vaccinations
. Developed after infection

32
Q

Passive immunity

A

. Short term
. No memory cells
. Faster process
. Passed on via breastmilk or across the placenta

33
Q

Importance of breast-feeding

A

Important as immune system of infants isn’t fully developed and functional at birth (greater risk of infection)

34
Q

Controlling spread of disease through vaccination

A

People vaccinated against disease are immune so they can’t develop infection and pass it on -> prevents spread of disease as there’s fewer people that have it

Biology IGCSE (21 decks)

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