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ah bio unit 2 > Parasitism > Flashcards

Parasitism Flashcards

1
Q

What is an ecological niche?

A

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

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2
Q

When does a species have a fundamental niche?

A

It occupies in the absence of any interspecific competition

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3
Q

When is a realised niche occupied?

A

In response to interspecific competition

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4
Q

What is a result of interspecific competition?

A

Competitive exclusion can occur, where the niches of two species are so similar that one declines to local extinction

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5
Q

What happens if the realised niches are sufficiently different?

A

Potential competitors can co-exist by resource partitioning

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6
Q

What is parasitism?

A

A symbiotic interaction between a parasite and its host (+/-)

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7
Q

What is a parasite?

A

An organism which gains benefit in terms of nutrients at the expense of its host

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8
Q

What is the reproductive potential of the parasite?

A

Greater than that of the host

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9
Q

What type of niche do most parasites have?

A

A narrow (specialised) niche as they are very host-specific

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10
Q

Why are many parasites degenerate?

A

As the host provides so many of the parasite’s needs, many parasites are degenerate, lacking structures and organs found in other organisms

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11
Q

What is the difference between an ectoparasite and an endoparasite?

A

An ectoparasite lives on the surface of its host, whereas an endoparasite lives within the tissues of its host

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12
Q

How many hosts does a parasite require to complete their life cycle?

A

Some parasites require only one host to complete their life cycle. Many parasites require more than one host to complete their life cycle

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13
Q

What is a vector in terms of parasites?

A

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

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14
Q

What is malaria caused by?

A

Plasmodium

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15
Q

What are schistosomes?

A

They cause the human disease schistosomiasis

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16
Q

What are viruses?

A

They are parasites that can only replicate inside a host cell

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17
Q

What do viruses contain?

A

Genetic material in the form of DNA or RNA, packaged in a protective protein coat

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18
Q

What are some viruses surrounded by?

A

A phospholipid membrane derived from host cell materials

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19
Q

What does the outer surface of a virus contain?

A

Antigens that a host cell may or may not be able to detect as foreign

20
Q

What are the viral life cycle stages?

A

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

21
Q

What do RNA retroviruses do and how does this affect viral genes?

A

They use the enzyme reverse transcriptase to form DNA, which is then inserted into the genome of the host cell. Viral genes can then be expressed to form new viral particles

22
Q

What is transmission?

A

Transmission is the spread of a parasite to a host

23
Q

What is virulence?

A

Virulence is the harm caused to a host species by a parasite

24
Q

How are ectoparasites transmitted?

A

Ectoparasites are generally transmitted through direct contact or by consumption of intermediate hosts

25
Q

How are endoparasites transmitted?

A

Endoparasites of the body tissues are often transmitted by vectors

26
Q

What are 2 factors that increase transmission rates?

A

The overcrowding of hosts when they are at high density. Mechanisms, such as vectors and waterborne dispersal stages, that allow the parasite to spread even if infected hosts are incapacitated

27
Q

How can parasites affect host behaviour?

A

Host behaviour is often exploited and modified by parasites to maximise transmission. The host behaviour becomes part of the extended phenotype of the parasite.

28
Q

How can parasites affect the host immune system?

A

Parasites often suppress the host immune system and modify host size and reproductive rate in ways that benefit the parasite growth, reproduction or transmission

29
Q

What types of aspects does the immune response in mammals have?

A

Both non-specific and specific aspects

30
Q

What are examples of non-specific defences?

A

Physical barriers, chemical secretions, inflammatory response, phagocytes, and natural killer cells destroying cells infected with viruses are examples of non-specific defences

31
Q

What are examples of specific cellular defences?

A

A range of white blood cells constantly circulates, monitoring the tissues

32
Q

What happens if tissues become damaged or invaded?

A

Cells release cytokines that increase blood flow resulting in non-specific and specific white blood cells accumulating at the site of infection or tissue damage

33
Q

Mammals contain many different lymphocytes, why is this useful against parasites?

A

Each possesses a receptor on its surface, which can potentially recognise a parasite antigen. Binding of an antigen to a lymphocyte’s receptor selects that lymphocyte to then divide and produce a clonal population of this lymphocyte. Some selected lymphocytes will produce antibodies, others can induce apoptosis in parasite-infected cells.

34
Q

What do antibodies possess and how does this affect antigen binding?

A

Antibodies possess regions where the amino acid sequence varies greatly between different antibodies. This variable region gives the antibody its specificity for binding antigen.

35
Q

What happens when the antigen binds to this binding site?

A

The antigen-antibody complex formed can result in inactivation of the parasite, rendering it susceptible to a phagocyte, or can stimulate a response that results in cell lysis. Memory lymphocyte cells are also formed.

36
Q

How have endoparasites evolved in order to invade the immune system?

A

They mimic host antigens to evade detection and modify host immune response to reduce their chances of destruction

37
Q

What does antigenic variation do?

A

In some parasites it allows them to change between different antigens during the course of infection of a host and it may also allow re-infection of the same host with the new variant.

38
Q

How do some viruses escape immune surveillance?

A

By integrating their genome into host genomes, existing in an inactive state known as latency

39
Q

When does the virus become active again?

A

When favourable conditions arise

40
Q

What is epidemiology?

A

The study of the outbreak and spread of infectious disease

41
Q

What is the herd immunity threshold?

A

The density of resistant hosts in the population required to prevent an epidemic

42
Q

How do vaccines help and why do they find it ‘difficult’?

A

Vaccines contain antigens that will elicit an immune response. The similarities between host and parasite metabolism makes it difficult to find drug compounds that only target the parasite.

43
Q

What has to be reflected in the design of vaccines?

A

Antigenic variation

44
Q

Why would it be difficult to design vaccines?

A

Some parasites are difficult to culture in the laboratory

45
Q

What are challenges that could arise?

A

Where parasites spread most rapidly as a result of overcrowding or tropical climates. These conditions make coordinated treatment and control programs difficult to achieve .

46
Q

How do civil engineering projects help?

A

Civil engineering projects to improve sanitation combined with coordinated vector control may often be the only practical control strategies

47
Q

How do improvements in parasite control help?

A

They can reduce child mortality and result in population-wide improvements in child development and intelligence, as individuals have more resources for growth and development

ah bio unit 2 (5 decks)

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