Unit 2: KA5 - Parasitism Flashcards

1
Q

Define the term: ecological niche

A

A multi-dimensional summary of tolerances and requirements of a species

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2
Q

Define the term: fundamental niche

A

The niche occupied in the absence of any interspecific competition

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3
Q

Define the term: Realised niche

A

The niche occupied in response to interspecific competition

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4
Q

Describe competitive exclusion

A

If the realised niches of two species are very similar, then one species will lose out in the competition and decline to local extinction

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5
Q

Describe resource partitioning.

A

This involves species exploiting different components of the resource.

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6
Q

Why is resource partitioning important?

A

If the realised niche is sufficiently different, then potential competitors can co-exist.

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7
Q

Define the term: parasitism

A

The symbiotic interaction between a parasite and a host.

The parasite gains energy and nutrients at the expense of the host.

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8
Q

Describe the interaction between a host and a parasite.

A

The parasite gains energy and nutrients at the expense of the host.

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9
Q

Describe the reproductive potential in parasitism.

A

The reproductive potential of the parasite is much greater than the host.

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10
Q

Describe the reproductive potential in a predator-prey relationship.

A

Similar reproductive potential

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11
Q

Describe a parasite’s niche.

A

Most parasites have a narrow (specialised) niche as they are host-specific

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12
Q

Describe why parasites are ‘degenerate’.

A

As they lack structures and organs found in other organisms, since the host provides so many of the parasite’s needs.

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13
Q

Define the term: Ectoparasite

A

A parasite which lives on the surface of their host

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14
Q

Define the term: endoparasite.

A

A parasite which lives inside their host.

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15
Q

Define the term: Definitive host

A

The organism in/on which the parasite reaches sexual maturity

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16
Q

Define the term: Intermediate host

A

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

17
Q

Define the term: vector.

A

A vector plays an active role in the transmission of a parasite and may also be a host

18
Q

What causes the human disease malaria?

A

plasmodium

19
Q

What causes the human disease schistosomiasis?

A

Schistosomes

20
Q

Describe the hosts of plasmodium.

A
  • Mosquitos are the definitive host and act as a vector

- Humans are the intermediate host

21
Q

Describe the hosts of Schistosomes

A
  • Humans are the definitive host

- Water snails are the intermediate host

22
Q

Describe viruses.

A

Viruses are parasites that can only replicate inside a host cell.
They contain genetic material in the form of DNA or RNA

23
Q

How is a virus’ genetic material packaged?

A

In a protective protein coat

24
Q

Describe the surface of viruses

A

It contains antigens, which the host cell may be able to detect as foreign.

25
Explain the Viral lifecycle
- Infection of host cell with genetic material - Host cell enzymes replicate viral genome - Transcription of viral genes and translation of viral proteins - assembly and release of new viral particles
26
What enzyme do RNA retroviruses make use of?
Reverse Transcriptase
27
Describe RNA Retroviruses
- Virus antigens attach to host surface - Virus RNA inserted into host cell - An enzyme converts RNA to DNA in cytoplasm - Viral DNA inserted into host cell genome - Viral proteins expressed and form new viral particles to be released
28
How are new viral particles produced?
The expression of viral genes
29
Define the term: transmission
The spread of a parasite to a new host
30
Define the term: virulence
The harm that a parasite causes to a host species
31
What two ways may ectoparasites be transmitted?
- Direct contact | - Consumption of intermediate host
32
How are endoparasites transmitted?
Vectors
33
What two factors can increase transmission rates?
- Overcrowding of hosts in high density | - A parasite's mechanisms of transmission, even when the host is incapacitated (vectors, waterborne dispersion etc.)
34
Define the term: extended phenotype.
A parasite's ability to exploit and change host behaviour in order to increase transmission rates.
35
What behaviours of a host may parasites alter?
- Alteration of host foraging - Movement - Habitat choice - Sexual behaviour - Anti-predator behaviour
36
How may parasites benefit from altering a host's body?
increased: - Growth - Reproduction - Transmission
37
What 3 things may parasites do to a host's body to gain benefits?
- Suppress immune system - Modify host size - Modify reproduction rate.