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A/ AH Biology: Unit 2 > Key Area 5-Parasitism > Flashcards

Key Area 5-Parasitism Flashcards

1
Q

What is symbiosis?

A

An intimate relationship between two different species where at least one of the species benefits nutritionally

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2
Q

What is a parasite?

A

A symbiont that benefits in terms of nutrition at the expense of their hosting

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3
Q

What is a host?

A

Something th parasite lives in or on and takes nutrients from

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4
Q

What percentage of all species are parasitic?

A

At least half

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5
Q

What percentage of all free living species are thought to host parasites?

A

All of them

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6
Q

How is reproductive potential in parasite-host relationship compared to predator-prey relationships

A

It is much greater as the reproductive potential of the parasite is far greater than that of the host

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7
Q

What is the parasite niche?

A

A multidimensional summary of the tolerances and requirements of a species

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8
Q

What is the size of a parasite niche?

A

Parasites tend to have a narrow niche as they are very host specific

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9
Q

Why can parasites be termed degenerate?

A

They often have a limited metabolism due to the fact that the host provides this function for the parasite so it doesn’t have to possess reproductive organs

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10
Q

What is an ectoparasite?

A

A parasite that lives on the surface of their host

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11
Q

What is an endoparasite?

A

A parasite that lives inside their host

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12
Q

Describe the balance between parasites and hosts?

A

A balance exists between the damage exerted by the parasite and the defence of the host, they constantly evolve with each generation

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13
Q

What is a definitive host?

A

The organisms in/on which the parasite reaches sexual maturity

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14
Q

What is an intermediate host?

A

An organism in/on which the parasite may complete some or part of its life cycle

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15
Q

What is a vector?

A

An organism that plays a role in the transmission of the parasite

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16
Q

What other function can a vector be?

A

A host

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17
Q

What is a fundamental niche?

A

The niche occupied in the absence of any interspecific competing influences

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18
Q

What is a realises niche?

A

The niche occupied in response to interspecific competition

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19
Q

What is competitive exclusion?

A

When two different species are so different one dies out completely

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20
Q

When does resource partitioning occur?

A

If the realises niche are so different-competition is reduced by organisms adapting to the pH and nutrients at different areas

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21
Q

What is transmission?

A

The spread of a parasite to a host

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22
Q

What is virulence?

A

The harm caused to the host species by the parasite

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23
Q

What are two qualities of a successful parasite?

A
  • rapid evolution

- efficient modes of transmission

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24
Q

What are two factors that increase transmission rates of parasites?

A
  • hosts density is high

- parasite has mechanisms of transmission even when host is incapacitated

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25
How do parasites alter host behaviour?
They alter the host behaviour in favour of the parasite and the behaviour becaimes part of the parasite’s extended phenotype
26
What are five host modifications?
``` Foraging behaviour Movement Sexual behaviour Habitat choice Anti-predator behaviour ```
27
What do parasites do to benefit themselves?
They suppress the host immune system, modify host size and modify host reproductive rate
28
How are parasites distributed?
Not uniformly
29
What parasite traits are favoured in distribution?
Parasites that can evolve rapidly and have the most efficient modes of transmission
30
What type of reproduction allows rapid evolution and population growth?
Both sexual and asexual
31
What is a non-specific response in mammals?
Physical barriers and chemical responses that fight anything that’s not you
32
Give three examples of non-specific responses in mammals
- inflammatory response - phagocytes - natural killer cells
33
What are phagocytes and how do they work?
Special white blood cells that engulf the parasite and digest it using enzymes held in lysosomes. When a tissue is damaged or a parasite enters, the damaged area gets warmer and redder because blood flow is increased to being more phagocytes to defend and attack
34
What do natural killer cells do?
Bring about apoptosis of non-self cells
35
Give so examples of specific cellular defence in mammals?
- immune survalence | - clinal selection of T-lymphocytes
36
What triggers a specific response?
When a non-specific response fails
37
What are the two types of lymphocytes?
- B-lymphocytes | - T-lymphocytes
38
How do B-lymphocytes work?
B-lymphocytes have foreign antigens presenter to them by phagocytes and replicate by mitosis to form clones which then either produce antibodies to fight antigen or become immunological memory cells
39
How do -lymphocytes work?
T-lymphocytes target specific infected or damaged cells and they trigger apoptosis. T-lymphocytes and clones and some remain as immunological memory cells
40
How are lymphocytes amplified?
Clinal selection
41
What is an immunological memory cell?
They remain in the blood after exposure to foreign antigens and if the body was to encounter this antigen again in the future these cells would replicate quickly and destroy it before a serious infection occurs
42
What is epidemiology?
The study of outbreaks and spread of infections
43
How can an epidemic be avoided?
If enough individuals are naturally resistant
44
What is the herd immunity threshold?
The number of resistant members needed to prevent an epidemic
45
Give three responses to immune systems and how they work?
- mimicking host antigens-this means they can evade detection - modify host-immune response-suppression of the host’s immune system - antigenic variation-this means they can evade detection as they change quicker than the host immune system can keep up with
46
Give the six common types of parasite?
- protists - Platyhelminthes - nematodes - anthropoids - bacteria - viruses
47
What is an indirect lifecycle?
When parasites require more than one host to complete their lifecycle
48
What are the two parasites that need more than one host in the life cycle?
- plasmodium spp - a protozoan that causes malaria | - schistosoma spp - a Platyhelminthe that causes schistosomiasis
49
How are endopaasites and ectoparasites of the main cavities of the boy usually transmitted?
By direct contact or by consumption of secondary host
50
How are endoparasites of the body usually transmitted?
By vectors
51
What parasites can complete their lifecycle in one host?
- viruses - bacteria - ectoparasitic arthropods - endoparasitic amoeba
52
What is an example of a bacterial human disease?
Tuberculosis
53
What are two examples of human viral diseases?
- influenza | - HIV
54
What genetic information is found in viruses?
Either RNA or DNA
55
How are all virusss composed?
A protein coat around some form of nucleic acid and some also have a lipid membrane made out of host resources
56
What are the steps in viral replication?
-
57
What is retrotransposin?
The DNA that originated from viral RNA
58
What enzyme allows reverse transcription of retrotransposin?
Reverse transcriptase
59
What does most of the genome in most eukaryotic cells consist of?
Retrotransposins thought to have arisen from retrotroviruses
60
What is the role of retrotransposins in host immunity?
The genes responsible for the variability of vertebrate antibodies
61
What is a retrovirus?
A virus that contains RNA rather than DNA
62
What are the reasons for difficulties in treatment and control of viruses?
- some parasites are difficult to culture in the laboratory - rapid antigen change has to be reflected in the design of vaccinations - similarities between host and parasite metabolism makes it difficult to find drug compounds that only target the parasite without negatively affecting the host
63
What are two practical control strategies for parasites?
- civil engineering projects to improve sanitation | - coordinates vector control
64
What did overcrowding do to control of parasites?
It makes control of parasites difficult as they spread most readily in overcrowded conditions
65
How can overcrowding occur?
War, rapidly growing cities in least developed countries
66
What type of climates increase the spread of parasites?
Tropical climates
67
What are two advantages of improving parasite control?
- reduce child mortality | - have population-wide improvements in child development an intelligence

A/ AH Biology: Unit 2 (5 decks)

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