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AH Biology > Unit 2 KA5 > Flashcards

Unit 2 KA5 Flashcards

1
Q

Ecological Niche

A

Multi dimensional summary of tolerances and requirements of a species

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2
Q

Fundamental Niche

A

Occupies in the absence of interspecific competition

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3
Q

Realised Niche

A

Occupied in response to interspecific competition

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4
Q

Competitive Exclusion

A

Can occur where the niches of two species are so similar that one declines to local extinction

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5
Q

What can happen as a result of realised niches

A

Potential competitors can co-exist by resource partitioning

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6
Q

Parasitism

A

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

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7
Q

What does a parasite gain from a host?

A

Benefit in terms of nutrients at the expense of its host

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8
Q

Reproductive potential if parasites

A

Greater than that of the host

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9
Q

Parasite Niche

A

Narrow as they are very host specific

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10
Q

Degenerate Parasites

A

As the host provides so many of its needs they lack structures and organs found in other organisms

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11
Q

Ectoparasite

A

Lives on surface of the host

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12
Q

Endoparasite

A

Lives within the tissue of its host

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13
Q

Definitive Host

A

Organism in which the parasite reaches sexual maturity

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14
Q

Intermediate Host

A

Required for the parasite to complete its life cycle

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15
Q

Vector

A

Plays an active role in transmission of the parasite and may also be a host

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16
Q

Malaria Life Cycle

A

An infected mosquito acting as a vector bites a human

Plasmodium enters the human bloodstream

Asexual reproduction occurs in the liver and then in the red blood cells

When red blood cells burst gametocytes are released into the blood stream

Another mosquito bites the infected humans and the gametocytes enter the mosquito

Matures into male and female gametes

Sexual reproduction can now occur

Mosquito can infect another human host

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17
Q

Schistosomes life cycle causing Schistosomiasis

A

Schistomes reproduce sexually in the human intestine

Fertilised eggs pass out via faeces into water where they develop into larvae

Larvae infect water snails

Asexual reproduction occurs

Produces another type of motile larvae

Escapes snail and penetrates skin of a human

Enters bloodstream

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18
Q

Viruses

A

Parasites that can only replicate inside a host cell

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19
Q

What do viruses contain

A

Genetic material (RNA or DNA) packed in a protective protein coat

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20
Q

What are some viruses surrounded by?

A

A phospholipid membrane derived from host cell materials

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21
Q

Outer surface of viruses

A

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

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22
Q

Viral life cycle stages

A

Infection if host cell with genetic material

Host cell enzymes replicate viral genome

Transcription of viral genes

Translation of viral proteins

Assembly and release of new viral particles

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23
Q

Enzyme used by RNA Retroviruses

A

Reverse Transcriptase which forms DNA which is then inserted into the genome of the host cell

24
Q

What can viral genes be expressed to form?

A

Viral particles

25
Transmission
Spread or a parasite
26
Virulence
Harm caused to a host species by a parasite
27
How are ectoparasites transmitted?
Direct contact
28
How are endoparasites of the body tissues transmitted?
Transmitted by vectors or by consumption of intermediate hosts
29
Factors increasing transmission rates
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
30
Maximising transmission
Host behaviour is often exploited and modified by parasites
31
What in the host is altered by parasites
Host foraging Movement Sexual behaviour Habitat choice Anti-predator behaviour
32
What becomes part of the extended phenotype of the parasite?
Host behaviour
33
What do parasites often do?
Suppress the host immune system Modify host size and reproductive rate in ways that benefit the parasite growth, reproduction or transmission
34
Non-specific defences examples
Physical barriers Chemical secretions Inflammatory response Phagocytes Natural killer cells destroying cells infected with viruses
35
Non specific defences further examples
Epithelial tissue blocks the entry of parasites Hydrolytic enzymes in mucus Saliva and tears destroy bacterial cell walls Low pH environments of the secretions of stomach Vagina and sweat glands denatured cellular proteins of pathogens
36
What do injured cells release?
Signalling molecules that result in enhanced blood flow to the site bringing antimicrobial proteins and phagocytes
37
Phagocytosis
Killing of parasites using phagocytes contained in lysosomes by engulfing them and storing them inside a vacuole
38
Natural killer cells
Can identify and attach to cells infected with viruses, releasing chemicals that lead to cell death by inducing apoptosis
39
What happens when tissues become damaged or invaded?
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
40
What do Iymphocytes possess
Possess a receptor on its surface which can potentially recognise a parasite antigen
41
Clonal population
Binding of an antigen to a lymphocyte receptor selects that lymphocyte to then divide and produce a clonal population
42
What can selected lymphocytes produce?
Antibodies which possess regions where the amino acid sequence varies greatly between different antibodies
43
What can lymphocytes induce?
Apoptosis I’m parasite infected cells
44
What does rhe variable region give the antibody?
Specificity for binding antigen
45
Antigen-antibody complex
When the antigen binds to the binding site 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
46
Secondary Response
Initial antigen exposure produces memory lymphocyte cells specific for that antigen that can produce a secondary response when the same antigen enters the body in the future. When this occurs antibody production is enhanced in terms of speed of production, concentration in blood and duration
47
Endoparasites evading the immune system
Mimic host antigens to evade detection Modify host immune response to reduce their chances of destruction Re-infection of the same host with the new variant
48
How do viruses escape immune surveillance?
Latency - integrating their genome into host genomes existing in an inactive state Virus becomes active again when favourable conditions arise
49
Epidemiology
Study of the outbreak and spread of infectious disease
50
Herd immunity threshold
Density of resistant hosts in the population required to prevent an epidemic
51
Vaccines
Contain antigens that will elicit an immune response
52
Why is it difficult to find drug compounds that only target the parasite?
Similarities between host and parasite metabolism
53
What must be reflected in the design of vaccines?
Antigenic variation
54
Factors that cause parasites to spread more rapidly
Overcrowding or tropical climates Makes coordinated treatment and control programs difficult to achieve
55
How does overcrowding occur?
Refugee camps that result from war or natural disaster Rapidly growing cities in LEDCs
56
Practical Control Strategy
Civil engineering projects to improve sanitation combined with co-ordinated vector control
57
Benefits of improving parasite control
Reduces child morality and result in population wide improvements in child development and intelligence as individuals have more resources for growth and development

AH Biology (6 decks)

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