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ADVH Biology > Unit 2 KA 5 ✓ > Flashcards

Unit 2 KA 5 ✓ Flashcards

Parasitism (49 cards)

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1
Q

What is a Niche?

A

A niche is a multi-dimensional summary of the tolerances and requirements of a species

NOTE: Tolerances and requirements can be biotic or abiotic

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2
Q

What is Intraspecific Competition?

A

Intraspecific competition is competition between members of the same species, for the exact same resources.
Intraspecific competition is usually more intense

e.g. Food, space, mates

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3
Q

What is Interspecific Competition?

A

Interspecific competion is competition between members of different species for similiar resources

e.g. Space, food

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4
Q

What is a Fundamental niche?

A

The fundamental niche is the niche a species occupies in the absence of any interspecific competition

NOTE: The maximum niche possible

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5
Q

What is a Realised niche?

A

A realised niche is occupied in response to interspecific competition

NOTE: The actual niche

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6
Q

What is Competitive Exclusion?

A

Competitive exclusion happens when two species have identical niches, this causes interspecific competition and one of the species declines to local extinction.

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7
Q

What is Resource Partitioning

A

Resource partitioning is when the realised niches of two species become sufficiently different, so the competitiors can co-exist.

NOTE: Avoids competitive exclusion

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8
Q

From KA 2.2 -

What is Parasitism?

A

Parasitism is a symbiotic interaction between a parasite and its host (+/-). The parasite gains benefit in terms of nutrients at the expense of its host

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9
Q

What is a Degenerate Parasite?

A

A degenerate parasite is a parasite that lacks structures and other organs found in other organisms as the host provides so many of the parasite’s need

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10
Q

What is a Endoparasite?

A

An endoparasite is a parasite which lives inside the tissues of its host

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11
Q

What is an Ectoparasite?

A

An ectoparasite is a parasite that lives on the surface of its host

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12
Q

What is a Definitive host?

A

A definitive host is an organism or/in which the parasite reaches sexual maturity and either produce gamete or undergo sexual reproduction

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13
Q

What is an Intermediate host?

A

An intermediate host is a host which may also be required for the parasite to complete its life cycle

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14
Q

What is a Vector?

A

A vector is an organism that plays an active role in the transmission of the parasite.
The vector can also be the host

e.g. Think of mosquitos transmitting malaria

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15
Q

What is Plasmodium?

A

Plasmodium is a single celled endoparasite which causes the human disease Malaria. It lives within female mosquitos.

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16
Q

What is the definitive host of plasmodium?

A

Mosquitos are the definitive host of plasmodium as sexual reproduction occurs

NOTE: Asexual reproduction occurs in humans

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17
Q

What are Schistosomes?

A

Schistosomes are endoparasitic flatworms that cause the human disease schistosomiases. They rely on vectors (water snail) to reach their definitive host (humans)

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18
Q

What is the definitive host of schistosomes?

A

Humans are the definitive host of schistosomes as sexual reproduction produces fertilised eggs in the human intestine

NOTE: Asexual reproduction occurs in snails

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19
Q

What is a Virus?

A

A virus is a parasite that can only replicate inside a host cell. They contain genetic material (DNA or RNA) packaged in a protective protein coat. The outer surface contains antigens. Some viruses are surrounded in a lipid membrane.

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20
Q

What does a host cell supply a virus with? (4)

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A
  • Nucleotides
  • Amino acids
  • ATP
  • Enzymes
21
Q

What is a RNA Retrovirus?

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A

An RNA retrovirus is a virus containing RNA, it uses the enzyme reverse transcriptase to form DNA which is inserted into the genome of the host cell, so viral genes can then be expressed to form new viral particles.

e.g. HIV

22
Q

What is Transmission?

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A

Transmission is how a parasite spreads to hosts

23
Q

What is Virulence?

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A

Virulence is how much harm a parasite causes their host and the affect it has on the hosts fitness

24
Q

How are ectoparasites transmitted?

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A

Ectoparasites are generally transmitted through direct contact

e.g. Headlice jump from head to head when people come in contact

25
How are endoparasites transmitted?
Endoparasites are transmitted by vectors, or by the consumption of an intermediate host
26
What factors can increase transmission rates? (3)
- A high density of hosts - Vectors and waterborne dispersal (transmission even if host is incapacitated) - Host behaviour
27
How can **Host behaviour** be altered by parasites? | (List 5 behaviours that can be altered)
Host behaviours like foraging, movement, sexual behaviour, habitat choice or anti-predator behaviour can be altered | e.g. An infected rat is no longer scared of cats, but attracted to them
28
Other than altering behaviour, what other changes can parasites cause in a host? (3)
- Supresses the hosts immune system - Modify the hosts size - Modify the reproductive rate in a way that benefits the growth, reproduction or transmission of the parasite
29
What is a **Pathogen**?
A pathogen is a disease causing microbe | e.g. Bacteria, Virus, Fungi
30
What is a **Non-specific, Physical defence** of the immune system?
A non-specific, physical defence is epithelial tissue, which blocks the entry of parasites | e.g. Skin (a physical barrier made up of epithelial tissue)
31
What are the **Non-specific, Chemical defences** of the immune system? (2)
Hydrolytic enzymes (found in lysosomes) in mucus, saliva and tears destroy bacteria cell walls. Low pH environmets like in stomach secretions, the vagina and sweat glands denatures the cellular proteins of pathogens
32
What are the **Non-specific, Cellular defences** of the immune system? (3)
- Inflammatory response - Phagocytosis - Natural killer cells
33
What is an **Inflammatory response**?
An inflammatory response is when injured cells release signalling molecules called *cytokines*. This results in enhanced blood flow which brings antimicrobial proteins and phagocytes to the injury site to deal with any pathogens
34
What is **Phagocytosis**?
Phagocytosis is the killing of parasites using powerful hydrolytic enzymes which are contained in lysosomes. The phagocyte enguls the parasite in a vacuole, the lysosome fuses to the vacuole and the enzymes destroy the parasite
35
What are **Natural killer cells**?
Natural killer cells are a type of lymphocyte that can identify and attach to cells which are infected with viruses. They release chemicals into the cell which cause cell death by inducing apoptosis
36
What are **Lymphocytes**?
Lymphocytes are a type of white blood cells, they are involved in the *specific* immune response. Lymphocytes have a receptor on their surface which can potentially (not always) recognise a parasite antigen
37
What are **Memory Lymphocytes**?
Memory lymphocytes are lymphocytes produced after the initial antigen exposure. They can then produce an enhanced, secondary response which is triggered when the same antigen reappears in future
38
What is **Antigen Mimicry** in endoparasites?
Antigen mimicry in endoparasites is when the endoparasite mimics the antiens of the "self-cell" in order to evade antibody detection
39
What is **Antigenic variation**?
Antigenic variation is when a parasite changes between different antigens during the course of infection in a host. This can allow for re-infection of the same host with a new *varient*
40
What is **Latancy**?
Latancy is when **viruses** escape immune surveillance by integrating their genome in host genomes and existing in an inactive state. The virus becomes active when favourable conditions arise
41
What is **Epidemiology**?
Epidemiology is the study of the outbreak and spread of infectious diseases
42
What is **Herd Immunity**?
Herd immunity is when a large percentage of a population is immunised, its important to reduce the spead of diseases
43
What is the **Herd Immunity Threshold**?
The herd immunity threshold is the density of resistant (immune) hosts required in a population to prevent an epidemic
44
What does the herd immunity threshold depend on? (3)
- The type of disease - The effectiveness of the vaccine - The density of the population
45
What is a **Vaccine**?
A vaccine is a preventative measure for parasitic infection, it contains antigens that elicit an immune response | NOTE: The antigens are in the form of dead/inactivated pathogens
46
Why do vaccines show **Antigenic Variation**?
Antigenic variation in vaccines causes the body to produce a range of antibodies, so the vaccine remains effective to several varients
47
Why is developing an effective vaccine for parisitic infections difficult? (2)
- The host and parasite metabolism is very similiar so it makes it difficult to find drug compounds that only target the parasite - Some parasites are difficult to culture in a lab, so designing a vaccine is difficult
48
Name some possible parasite control strategies (2) -
- Co-ordinated vector control - Civil engineering projects to improve *sanitation*
49
How does parasite control benefit children? (2)
- Reduced child mortality - Improvements in child development and intelligence

ADVH Biology (11 decks)

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