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Adv H 2.5 Qs
Parasitism RR Qs
66
Biology
Not Applicable
03/26/2022

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Term
What is the definition of an ecological niche?
Definition
multidimmentional list of tolerance and requirements for a species
Term
What is a fundamental niche?
Definition
the niche an organism occupies in the absence of interspecific competition.
Term
What is a realised niche?
Definition
the niche an organism occupies in the presence of interspecific competition.
Term
What conditions are needed to cause competitive exclusion?
Definition
interspecific competition where the niches of two species are very similar
Term
What is the result of competitive exclusion?
Definition
one of the competing species declines to local extinction
Term
What causes resource partitioning?
Definition
when the realised niches of two species are sufficiently different
Term
What is the result of resource partitioning?
Definition
potential competitors can co-exist
Term
What is parasitism?
Definition
Symbiotic relationship between members of two different species where one is harmed and the other benefits.
Term
Give two distictions between host-parasite and predator-prey relationships.
Definition
Parasites live on or in their host(s)/ Parasites have far greater reproductive potential than the host. This is not true of predator/ prey relationships.
Term
What are the main features of most parasites niches?
Definition
narrow & specialised as they are very host specific
Term
What is meant when we say many parasites are degenerate?
Definition
they lack many structures as the host provides many of their needs
Term
What type of parasite lives on the surface of its host?
Definition
ectoparasite
Term
What type of parasite lives within the tissues of its host?
Definition
endoparasite
Term
Explanation of co-evolution of host-parasite
Definition
When selection of features of the host improve to resist parasititic infection, the parasite will evolve features to overcome this resistance, according to the RQH.
Term
What is a definitive host?
Definition
Host in which the parasite reaches sexual maturity
Term
What is an intermediate host?
Definition
Host in which the parasite completes part of its lifecycle and may proliferate.
Term
What is a vector?
Definition
Organism which plays an active role in the transmission of the parasite. And may also be a host.
Term
State the disease/host(s)/vector of Plasmodium.
Definition
Malaria/ Human (intermediate)/Mosquito (definitive)/ mosquito
Term
State the disease/host(s)/vector of Shistosoma.
Definition
Shistosomiasis/ Human (definitive)/ Snail (intermediate)/ none
Term
In malaria red blood cells burst and release gametocytes. What are gametocytes?
Definition
the precursors of male and female gametes
Term
Whhat are viruses?
Definition
parastites that can only repluicate inside a host cell.
Term
Describne the structure of a virus.
Definition
genetic material (DNA or RNA) packaged in a protective protein coat.
Term
Which part of a host cell can a virus be surrounded by?
Definition
the host cells phospholipd membrane
Term
What is on the outer surface of a virus that the host cell may or may bot be able to detect as foreign?
Definition
antigens
Term
List the stages of the viral life cycle in order.
Definition
infect host with viral genetic material, hostcell enzymes replicate the viral genome, transcription of viral genome, and translation to make viral proteins, assembly and release of new viral particles
Term
Name the enzyme used by retroviruses to form DNA.
Definition
Reverse Transcriptase
Term
What happens to the DNA made by reverse transcriptase for retroviruses?
Definition
it is inserted into the host cell's genome.
Term
What is meant by 'transmission' of a parasite?
Definition
Spread of the parasite.
Term
What is meant by 'virulence' of a parasite?
Definition
Harm caused by the parasite to a host
Term
Give 2 ways in which ectoparasites are transmitted.
Definition
Direct contact or consumption of intermediate hosts
Term
How are endoparasites often transmitted?
Definition
by vectors
Term
Give 3 factors which increase the transmission rate of parasites
Definition
overcrowding of hosts & the mechanism (eg vectors and waterborne dispersal) that allow spread even if host is incapacitated
Term
Give examples of a host's behaviour being part of the extended phenotype of the parasite.
Definition
FAMSH- changes in these behaviours: foraging,anti-predator behaviour/movement/sexual/ habitat choice.
Term
Give ways that a parasite can affect a host to benefit the parasite growth, reproduction or transmission.
Definition
suppress the host immune system, modify host size, modify host reproductive rate
Term
Name the type of tissue that acts as a physical barrier to parasites.
Definition
epithelial tissue
Term
Name the chemical secretions that are part of the non-specific defence against parasites.
Definition
mucus, saliva, tears, stomach acid
Term
What do mucus, saliva and tears contain to destroy bacterial cell walls?
Definition
hydrolytic enzymes
Term
How do the secretions of the stomach, vagina and sweat glands provide non-specific defence?
Definition
the low pH denatures cellular proteins of pathogens.
Term
Name the two types of white blood cells involved in the non-specific defences.
Definition
phagocytes and natural killer cells
Term
Which type of white blood cell can kill parasites by engulfing them then releasing powerful enzymes from lysosomes.
Definition
phagocytes
Term
How do natural killer cells provide non-specific defence?
Definition
attach to infected cells, release chemicals that induce apoptosis
Term
Name the chemicals released by cells to increase blood flow, delivering more white blood cells to a damaged or infected area.
Definition
cytokines
Term
What happens when a lymphocyte binds to an antigen of a pathogen?
Definition
a clonal population of the specific lymphocyte is produced
Term
Name the Y shaped proteins produced by some lymphocytes (B).
Definition
antibodies
Term
Instead of producing antibodies what do other lymphocytes do to provide specific defence?
Definition
induce apoptosis in infected cells
Term
What happens at the variable region on an antibody?
Definition
binding of specific antigen
Term
What can happen to an antigen-antibody complex?
Definition
destroyed by phagocytes OR cell lysis (cell bursts)
Term
What type of cells are responsible for the secondary response in the immune system?
Definition
memory lymphocyte cells
Term
Give three ways the secondary immune response is different to the initial immune response.
Definition
secondary response is faster, produces higher concentration of antibodies and lasts longer than initial response
Term
Give two ways that endoparasites can evade the host's immune system.
Definition
mimic host antigens to evade detection, modify host immune response to avoid destruction
Term
What is antigenic variation?
Definition
when a parasite changes antigens during the course of infectionof a host
Term
What is the imapct on the host of antigenic variation?
Definition
could be reinfected with the new variant
Term
What is latency in viruses?
Definition
when virus exists in host in an inactive state
Term
How do some viruses avoid immune surveillance?
Definition
they integrate their genome into the host genome
Term
When would an inactive virus become active again?
Definition
when the conditions become favourable
Term
What is epidemiology?
Definition
the study of the outbreak and spread of infectious disease.
Term
What is the herd immunity threshold?
Definition
Density of resistant hosts (immune) reqired to prevent an epidemic in a population.
Term
What do vaccines contain that will elicit and immune response?
Definition
antigens
Term
What do vaccine designers / developers have to take into account?
Definition
antigenic variation
Term
Why is it difficult to find drugs that only target parasites?
Definition
the metabolism of the parasite and host are similar
Term
What can make it difficult to design vaccines?
Definition
parasites can be difficult to culture in the laboratory
Term
Name some methods of disease prevention (5)
Definition
Vaccination/ sanitation/ civil engineering projects (sewerage/drainage)/ ccordinated vector control/ drugs (e.g. anti-malarials)
Term
Describe two problems with vacination use.
Definition
Reaching affected communities which may be in rural locations/ rapid antigenic evolution of parasites
Term
What issues arise in LEDCs that make diease control difficult?
Definition
overcrowding in refugee camps afetr war / natural disaster or rapidly growing cities
Term
What type of climate causes parasites to spread quickly?
Definition
tropical
Term
3 benefits of better parasite control
Definition
Reduction in child mortality/ more productivity in population due to fewer days absent from work/ better child development and intelligence since more energy is available for growth and resilience in children
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