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A Level Biology > 12.1 - Animal and Plant Pathogens > Flashcards

12.1 - Animal and Plant Pathogens Flashcards

1
Q

Define disease

A

An illness or disorder of the body or mind that leads to poor health

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2
Q

Define infectious diseases

A
  • these are diseases caused by organisms known as pathogens
  • they are passed from infected to uninflected people
  • some also affect animals and are passed from animals to humans
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3
Q

What are some examples of infectious diseases ?

A
  • cholera
  • malaria
  • HIV/aids
  • tuberculosis
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4
Q

Define non infectious diseases

A

long term degenerative diseases that are not caused by pathogens

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5
Q

What are some examples of non infectious diseases ?

A
  • lung cancer
  • chronic obstructive pulmonary disease COPD
  • sickle cell anemia
  • cystic fibrosis
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6
Q

What are the types of pathogens ?

A
  • bacteria
  • fungi
  • viruses
  • protoctista
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7
Q

What are vectors ?

A

Carry pathogens from one organism to another

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8
Q

What are some common vectors ?

A
  • water
  • insects
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9
Q

What is a pathogen ?

A

A microorganism that causes disease

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10
Q

How do bacteria cause disease ?

A

By destroying cells and releasing waste products and/ or toxins

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11
Q

What are the two ways bacteria can be classified ?

A
  1. By their basic shapes
  2. By their cell walls
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12
Q

What are the 5 different shapes bacteria can be ?

A
  • they may be :
  • rod shaped ( bacilli )
  • spherical ( cocci )
  • comma shaped ( vibrios )
  • spiralled ( spirilla )
  • corkscrew ( spirochaetes )
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13
Q

What are the two types of bacterial cell walls ?

A
  • gram positive bacteria
  • gram negative bacteria
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14
Q

How do these two bacterial cell walls differ ?

A
  • have different structures
  • react differently with a process called gram staining
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15
Q

What happens when staining gram positive bacteria ?

A
  • look purple- blue under the light microscope
  • for eg. Methicillin- resistant staphylococcus aureus ( MRSA )
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16
Q

What happens when staining gram negative bacteria ?

A
  • appear red
  • eg. Gut bacteria E.coli
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17
Q

Why is it key to identify between the different cell walls ?

A

type of cell wall affects how bacteria react to different antibiotics

18
Q

What are some features of a gram positive cell wall excluding colour with gram staining ?

A
  • thicker but less tough
  • more susceptible to antibiotics which damage the cell wall
  • more peptidoglycan
  • lower lipid content
  • more prominent mesosome
19
Q

What makes a gram- positive cell wall go purple- blue with gram staining ?

A

The peptidoglycan in their cell wall retains crystal violet stain

20
Q

What are some features of a gram negative cell wall ?

A
  • thinner but tougher
  • higher lipid content due to outer cell membrane
  • less susceptible to antibiotics
21
Q

What are viruses ?

A

Non- living infectious agents

22
Q

How large is a virus diameter ?

A

0.02-0.3 diameter

23
Q

What is the basic structure of a virus ?

A

Some genetic material either DNA or RNA surrounded by a protective protein coat

24
Q

What is the mechanism of infection of a virus ?

A
  • they attach to the cell and inject their genetic material
  • this takes over their biochemistry of the boar cell to make more viruses
  • this is via inserting itself into the host DNA
  • until so many are made that the host cell is lysed ( bursts)
  • and new viruses are released
25
What 2 things make viruses very successful pathogens ?
- reproduce rapidly - evolve by developing adaptations to their host
26
What proportion of naturally occurring viruses are pathogenic ?
All of them
27
What is a bacteriophage ?
A virus which attacks a bacteria - take over bacterial cells and use them to replicate - destroying the bacteria at the same time
28
What is a virophage and give a example ?
- a virus which infects other viruses - eg. Sputnik virus
29
Are protoctistia eukaryotic ie prokaryotic ?
- Eukaryotic - with a vide variety of feeding methods
30
Are protocistia unicellular or multicellular ?
- Unicellular - they can group into colonies
31
What type of protists cause disease ?
Parasitic
32
What is meant by parasitic ?
They use people or animals as their host organism
33
What are pathogenic protists ?
Need a vector to transfer them to their hosts
34
Are fungi multicellular or unicellular ?
- usually multicellular - with the exception of yeasts
35
How do fungi feed ?
- many fungi are saprophytes meaning they feed on dead and decaying matter - some fungi are parasitic meaning they feed on living plants and animals - fungi cannot photosynthesise and they digest food extracellular lay before absorbing the nutrients
36
How do fungi reproduce ?
- produce millions of spore - can spread through huge distances and spread their distances quickly among crops
37
What organelles do yeast have ?
- nucleus - mitochondria - cell membrane - permanent vacuole
38
What are the two main pathogenic modes of action ?
1. Damaging host tissues directly 2. Producing toxins which damage host tissue
39
How do fungi damage the tissues of their host organism ?
- digest living cells and destroy them - this combined with the response of the body to the damage caused by the fungus gives the symptoms of disease
40
How do protoctista damage the host cells directly ?
- take over cells and break them open as the new generation emerge - they do not take over the genetic material of the cell - simply digest and use the cell contents as they reproduce
41
How do viruses damage the host tissues directly ?
- take over cell metabolism - the viral genetic material gets into the host cell and is inserted into the host DNA - the virus them uses the host cell to make new viruses which then burst out of the cell destroying it - then do read it infect other cells
42
How do bacterial toxins damage host cells ?
- by breaking down the cell membranes - some damage or inactive enzymes and some interfere with the host cell genetic material so the cells cannot divide - these toxins are a by- product of the normal functioning of the bacteria

A Level Biology (54 decks)

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