Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

A Level Biology > Diseases and the Immune System > Flashcards

Diseases and the Immune System Flashcards

1
Q

Pathogen

A

Organisms that cause disease
- they take nutrition from the host as an energy source (except viruses)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

4 types of infectious organisms

A
  • bacteria
  • fungi
  • viruses
  • protoctista
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Bacteria

A
  • smaller than eukaryotic cells
  • reproduce rapidly
  • damage cells through release of toxins
  • TB, bacterial meningitis, ring rot
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Fungi

A
  • often lives in the skin- hyphae form a mycelium
  • reproductive hyphae grow into the skin and release spores
  • lives in vascular tissue of plants to gain nutrients
  • hyphae release extracellular digestive enzymes to break down cellulose
  • black sigatoka, ringworm, athletes foot
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Protoctista

A
  • needs a vector to enter the host e.g. mosquito
  • enter host cell and feed on the contents of the cell
  • malaria parasite plasmodium has immature forms which feed on haemoglobin
  • blight, malaria
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Virus

A

• viruses invade host cells and take over genetic machinery and other organelles
• Cause cell to manufacture more copies of the virus
• Host cell eventually bursts, releasing new viruses to invade new host cells
• HIV, influenza, tobacco mosaic virus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Direct transfer

A
  • physical contact
  • fecal transmission
  • droplet infection
  • spores transmission
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Indirect transmission

A
  • transmission via vectors
  • e.g. malaria via mosquitoes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

7 factors which affect transmission

A
  • overcrowding
  • nutrition
  • compromised immune system
  • poor waste disposal
  • climate change
  • socioeconomic factors
  • culture
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

2 main types of plant defences

A
  1. Passive
  2. Active
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Do plants have an immune system

A

No- plants don’t have an immune system so they use defences to prevent extensive damage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What can passive defences be split into

A
  1. Physical
  2. Chemical
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Physical defences

A

Cellulose cell wall- physical barrier, contains chemicals defences when a pathogen is detected

Waxy cuticle- prevents water collecting, which can contain pathogens

Bark- contains chemicals which will work against pathogens

Tylose formation- is a balloon like projection which fills the xylem, acting as a plug to prevent the xylem from carrying water, so prevents the spread of pathogens. Contains high levels of terpenes which are toxic to many pathogens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Chemical defences

A
  • Hydrolytic enzymes
  • Defensive proteins
  • Alkaloids
  • Phenols
  • Terpenoids

Tylose and tannins are in bark before infection, however use lots of energy to create so aren’t made until infection is detected

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Chemical defences: hydrolytic enzymes

A

Widespread throughout all plants and break down the cell wall of invading organisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Chemical defences: defensive proteins

A

Destroy pathogens by engulfing and destroying them

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Chemical defences: alkaloids

A

release a strong scent/odour- toxins. Have bitter taste to prevent herbivores feeding on them

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Chemical defences: phenols

A

contain antitoxin properties which help destroy pathogens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Chemical defences: terpenoids

A

released to signal to the rest of the plant to initiate response. Contain antibacterial properties

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Active defences

A

When a plant becomes infected with a pathogen, proteins and glycolipids in the cell wall of the plant detect the, and signal chemical defences, and increase physical defences

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Examples of active defences

A
  • cellulose cell wall thickens
  • oxidative bursts that produces highly reactive oxygen molecules which can damage the cells of invading organisms
  • increase in production of chemicals
  • callose is synthesised and deposited in both sieve plates and between cell wall and cell membranes of surrounding cells, blocking plasmodesmata / flow through the phloem
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are cell walls of bacteria made from

A

Peptidoglycan

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is gram staining

A

A method used to distinguish between different groups of bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Gram negative

A

Appear red under a light microscope
E.g. E-coli

25
Q

Gram positive

A

Appear purple/blue under a light microscope
E.g. MRSA

26
Q

How do pathogens infect hosts

A
  • damage host tissue directly
  • produce toxins which damage host tissue (indirectly)
27
Q

How do viruses, protoctista and fungi damage cells

A

Directly

28
Q

How do bacteria and fungi damage cells

A

Indirectly

29
Q

Bacteria examples

A
  • Tuberculosis
  • Bacterial meningitis
  • Ring rot (plants)

TBR

30
Q

Tuberculosis

A

Characteristics
Infect lungs - chronic cough, bloody mucus, fatigue

Transmission
Direct
- airborne droplets

31
Q

Bacterial meningitis

A

Characteristics
Fever, neck stiffness, headaches, altered mental status

Transmission
Direct
- airborne droplets

32
Q

Ring rot

A

Characteristics
Host- potato, tomato
- infects vascular tissue, prevents transport if water, in tubers (causes black ring)

Transmission
Direct
- contact with other infected tubers

33
Q

Virus examples

A

HIV/AIDS
Influenza
Tobacco mosaic virus

HIT

34
Q

HIV / AIDS

A

Characteristics
Weakens immune system
- fever, diarrhoea, fatigue, weight loss

Transmission
Direct
- transfer of sexual bodily fluids

35
Q

Influenza

A

Characteristics
High temperature, body aches, fatigue
- infects cells that line the airway

Transmission
Direct
- airborne droplets

36
Q

Tobacco Mosaic Virus

A

Characteristics
Host- tobacco
- yellowing of leaves, produces mosaic pattern

Transmission
Direct- contact with infected leaves
Indirect- vectors (aphids)

37
Q

Fungi examples

A
  • black sigatoka
  • ringworm
  • athletes foot

BRA 👙

38
Q

Black sigatoka

A

Characteristics
Host- bananas
- leaves can’t photosynthesise
- produce black streaks

Transmission
Direct
- spores (rain splash and wind)

39
Q

Ringworm (cattle)

A

Characteristics
Ring shaped rash on skin

Transmission
Direct
- contact with infected cattle

40
Q

Athlete’s foot

A

Characteristics
Itchy white patches & cracked skin between toes

Transmission
Direct
- contact with infected items

41
Q

Protoctista examples

A
  • Blight
  • Malaria
42
Q

Blight

A

Characteristics
Small, dark brown marks on leaves
- destroys crops - inedible

Transmission
Direct
- spores (windborne)

43
Q

Malaria

A

Characteristics
Fever, chills, fatigue, nausea, headaches

Transmission
Indirect
- bite from infected anopheles mosquito

44
Q

Types of transmission

A

Direct or Indirect

45
Q

Types of transmission: direct

A

Direct contact
- kissing/contact with bodily fluids (HIV)
- skin to skin contact (athlete’s foot)
- microorganisms from faeces on the hands

Inoculation
- broken skin (HIV)
- animal bites (rabies)
- puncture wounds / sharing needles (septicaemia)

Ingestion
- contaminated food or water (dysentery)
- e.g. mould

46
Q

Types of transmission: indirect

A

Formites
- inanimate objects that can carry infection- bedding, socks, cosmetics (athletes foot)

Droplet infection (inhalation)
- sneezing, coughing, talking- in saliva & mucus (influenza)

Vectors
- transmits infection from one host to another (malaria by anopheles mosquito)

47
Q

Direct transmission between plants

A
  • direct contact of a healthy plant with an infected plant

E.g. ring rot, black sigatoka, tobacco mosaic virus, blight (tomato & potato)

48
Q

Indirect transmission between plants

A

Soil contamination
• pathogens (bacteria or virus) or spores (fungi) can be left behind in the soil and infect the next crop
• Some pathogens can even survive the composting process, and so compost can carry infection
• E.g.black sigatoka spores, ring rot spores

Vectors
• wind- e.g. black sigatoka carried between Caribbean islands
• Water- spores swim in surface film, raindrop splashes
• Animals- insects and birds carry pathogens as they feed
• Humans- on hands, clothing, formites, farming practices and transporting crops around the world e.g. ring rot can survive in farming machinery

49
Q

Factors affecting disease transmission

A
  • crop variety (monoculture)
  • overcrowding
  • poor mineral nutrition
  • damp, warm conditions
    -climate change
  • lack of healthcare workers
  • *lack of sanitation *
50
Q

Strategies to prevent spreading of pathogens

A
  • wear masks / cover mouth + nose when cough
  • ensure areas are well ventilated / outside where possible
  • trained healthcare workers + educate people
  • wash hands after toilet / before eat
51
Q

Non specific defences

A
  1. Barriers
  2. Inflammatory response
  3. Clotting and wound repair
52
Q

Barriers to prevent entry

A
  • hair
  • skin
  • mucus
  • tears
  • stomach acid- hydrochloric acid
  • expulsion reflexes- coughing, sneezing
  • cilia- line the airways
  • lysozymes- in tears and urine
53
Q

How do ciliated epithelial cells defend against pathogens

A
  • cilia sweep mucus with trapped pathogens out of the airway
  • goblet cells produce and secrete mucus (contains lysozymes)
54
Q

How does skin protect against pathogens

A
  • microorganism flora outcompetes pathogens for space in the surface of the Boyd
  • sebum oil inhibits pathogen growth
  • physical barrier between pathogens and body
  • waterproof mechanical barrier
55
Q

How does mucous membranes defend against pathogens

A
  • cilia- contain phagocytes
  • produce mucus to trap pathogens to be broken down
56
Q

How does stomach acid defend against pathogens

A
  • bacteria can’t survive in low pH
  • kills bacteria and parasites that have been swallowed
57
Q

How does lysozymes (in tears and urine) defend against pathogens

A

Contains enzymes that breaks down the cell wall of bacteria

58
Q

How do expulsive reflexes defend against pathogens

A
  • expel pathogens back outside the body
  • eject mucus containing pathogens from gas exchange system

A Level Biology (25 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions