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Advanced Higher Biology > Unit 2 - section 5 > Flashcards

Unit 2 - section 5 Flashcards

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1
Q

What is a parasite?

A

An organism that forms a symbiotic relationship with a host where it benefits at the expense of the host

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2
Q

What is a host?

A

An organism that harbours a parasite

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3
Q

How common are parasites?

A

At least 50% of all species are parasitic

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4
Q

How likely are free living organisms to be hosts?

A

All free living organisms are thought to be hosts

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5
Q

Compare the reproductive potential of host-parasites to predator-prey relationships

A

When compared to predator-prey relationships the reproductive potential of the parasite is much greater than that of the host

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6
Q

What is an ecological niche?

A

A complex outline of the tolerances and requirements of a species

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7
Q

Why do parasites have a narrow niche?

A

Due to high host specificity

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8
Q

Why do parasites have limited structures?

A

Parasites are degenerate, lacking in structures and organs found in other organisms, because the host provides many of the parasites needs

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9
Q

Compare ectoparasites and endoparasites

A

Ectoparasites live on the surface of their host eg fleas on cats

Endoparasites live inside their hosts eg tapeworms live in hosts intestine

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10
Q

Compare definitive and intermediate hosts

A

Definitive - host the organism reaches sexual maturity in/on

Intermediate - host the organism completes some part of its lifecycle in/on

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11
Q

What is a vector?

A

An organism that plays a role in the transmission of the parasite. Vectors can also be hosts

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12
Q

Describe the two types of niche

A

Fundamental - niche the organism occupies when there is no other species competing for space or resources

Realised - niche the organism occupies when there is competition from other species

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13
Q

What is competitive exclusion?

A

When two different species occupy similar niches and are in intense competition with each other the weaker of the two species may die out

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14
Q

What is resource partitioning?

A

When competing species occupy different realised niches compromising over resources and managing to exist simultaneously

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15
Q

What do transmission and virulence mean?

A

Transmission is the spread of a parasite to a host

Virulence is the deleterious effect the parasite has on the host

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16
Q

What are 2 qualities of a successful parasite?

A

Easily transmitted

Evolve rapidly

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17
Q

What factors increase transmission rate of parasites?

A

Host density is high

Parasite has mechanisms of transmission even when the host is incapacitated

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18
Q

What are 5 aspects of host behaviour that can be altered to exploit the parasite phenotype?

A 
Foraging
Movement 
Sexual behaviour 
Habitat choice 
Anti-predator behaviour
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19
Q

Why do parasites often suppress the immune system, size and reproductive rate of the host?

A

For their own benefit

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20
Q

Describe the distribution of parasites

A

Non-uniformly

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21
Q

How does parasites having both sexual and asexual phase benefit them in terms of evolution rates?

A

Allows for rapid evolution and rapid population growth

22
Q

What are the non-specific barriers mammals have to parasites?

A 
Physical barriers 
Chemical secretions 
Inflammatory response 
Phagocytes 
Natural killer cells
23
Q

Describe the process of phagocytosis

A

Phagocytes are special white blood cells that engulf parasites by enfolding their plasma membrane around the membrane.

The parasite is brought into the phagocyte in a vacuole or vesicle. Phagocytes contain organelles called lysosomes that are filled with digestive enzymes. The lysosomes fuse with the vacuole, releasing the digestive enzymes allowing the enzymes to digest the parasite

24
Q

What is specific cellular defence?

A

Responses that are triggered when non-specific responses fail. The response will be specific to the foreign antigen present

25
Q

What are the 2 types of lymphocytes and what are their roles?

A

B lymphocytes - produce specific antibodies in response to foreign antigens

T lymphocytes - destroy specific cells or damaged tissue by bringing about cell apoptosis

26
Q

What is clonal selection of lymphocytes?

A

Where lymphocytes become amplified with some clones being used for immediate defence and other clones acting as memory cells

27
Q

What are immunological memory cells?

A

Cloned lymphocytes that remain in the body allowing it to respond faster if the individual is exposed to the same antigen a second time

28
Q

What is epidemiology?

A

The study of the outbreak and spread of infectious diseases

29
Q

What is herd immunity threshold?

A

The number of resistant members needed to prevent an epidemic

30
Q

What are the possible parasite responses to host responses?

A

Mimicking host antigens
Modifying host-immune response
Antigenic variation

31
Q

Why do parasites mimic host antigens?

A

Allows them to evade detection

32
Q

Why do parasites modify host-immune response?

A

To suppress the hosts immune system

33
Q

Why do parasites change their outer antigens?

A

To evade detection as they change quicker than the host immune system can keep up with

34
Q

What are the 6 common types of parasites and give examples of each?

A 
Protists - Protozoa, algae, diatoms
Plathyhelminthes - flatworms 
Nematodes - roundworms
Arthropods - ectoparasites 
Bacteria - TB, cholera 
Viruses - colds, flu
35
Q

What are two examples of parasites that require more than one host?

A

Malaria

Schistosomiasis

36
Q

How are endoparasites and ectoparasites of the main body cavities transited?

A

Direct contact or by consumption of secondary hosts

37
Q

How are endoparasites of body tissues often transmitted?

A

By vectors

38
Q

Give examples of parasites that can complete their lifecycle in one host

A

Ectoparasitic arthropods
Endoparasitic protists
Bacteria and viruses

39
Q

Give an example of a bacterial human disease

A

Tuberculosis

40
Q

Give two examples of viral human diseases

A

Influenza

HIV

41
Q

What is a virus?

A

A tiny infectious agent that can only replicate inside a host

42
Q

What form is genetic information found in viruses?

A

DNA or RNA packaged in a protective protein coat

43
Q

Describe the basic structure of a virus

A

Viruses are composed of a protein coat around some form of nucleus acid (DNA/RNA). Some viruses also have a lipid membrane made out of host resources. The antigens in this protein coat may or may not be recognised by the host immune system

44
Q

What is a rectotransposon?

A

Segment of DNA that carries off reverse transcription before being inserted into a new site on the genome

45
Q

What is thought to be the origin of retrotransposons in the eukaryotic genome?

A

Retroviruses

46
Q

What is the role of retrotransposons in host immunity?

A

??

47
Q

What is a retrovirus?

A

They are thought to be the origin of retrotransposons in the eukaryotic genome

48
Q

What enzyme is involved in DNA formation in retroviruses?

A

Reverse transcriptase

49
Q

What are the 3 challenges faced in the treatment and control of parasites?

A

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

50
Q

What are 2 practical control strategies for parasites?

A

Civil engineering projects to improve sanitation

Coordinated vector control

51
Q

Under what conditions do parasites thrive and what impact does this have on certain countries in the world?

A

Thrive in tropical climates and areas where there is overcrowding.

Has the greatest impact on countries where they face the difficulties of war/refugee camps, aftermath of natural disasters or rapidly growing cities in the least developed countries

52
Q

What are 2 advantages of improving parasite control?

A

Reduce child mortality

Allows improvement in child development and intelligence

Advanced Higher Biology (13 decks)

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