2.5 parasitism

Question 1

what is an ecological niche?

Answer 1

Is a multi-dimensional summary of tolerances and requirements of a species.

Question 2

what is a fundamental niche?

Answer 2

Occupies in the absence of any interspecific competition.

Question 3

What is a realised niche?

Answer 3

Occupied in response to interspecific competition.

Question 4

What can occur as a result of interspecific competition?

Answer 4

Competitive exclusion can occur where the niches of two species are so similar that one decline to local extimction.

Question 5

When realised niches are sufficiently different, potential competitors can co-exist?

Answer 5

Resource partitioning which resources are split between potential competitors.

Question 6

The reproductive potential of a parasite is more of…

Answer 6

That than its host.

Question 7

Most parasites have…

Answer 7

Narrow, specialised niche as they host-specific.

Question 7

Parasites are degenerate what does this mean?

Answer 7

Rely on hosts to provide so they lack structures and organs such as digestive system.

Question 7

What is an ectoparasite and endoparasite?

Answer 7

Ectoparasite lives on the surface of its host, Endoparasite lives within the tissue of the host.

Question 8

What is a definitive host?

Answer 8

Organism in which parasite reaches sexual maturity.

Question 9

What is the intermediate host?

Answer 9

May also be required for parasite to complete its life cycle.

Question 10

What is a vector?

Answer 10

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

Question 10

What causes malaria?

Answer 10

Parasite plasmodium, mosquito bites a human and plasmodium enters the bloodstream, asexual reproduction occurs in the liver then red blood cells which burst and release gametocytes in to the bloodstream.

Question 10

What happens if a mosquito enters am infected human?

Answer 10

Gametocytes enter the mosquito, maturing into male and female gametes and allowing sexual reproduction to occur>

Question 10

How do schistosome work?

Answer 10

Reproduce sexually in the human intestine and fertilised eggs pass out via faeces into water where they develop into larvae that infact water snails, where asexual reproduction occurs producing another type of motile larvae escape the snail and penetrate the skin of humans, entering the blood stream.

Question 10

Schistosome parasites cause….

Answer 10

Schistosome.

Question 11

What are viruses?

Answer 11

Can only replicate inside the host cell. Genetic material in the form of DNA or RNA, packaged in a protein coat.

Question 12

Some viruses are surrounded by a phospholipid membrane derived from where?

Answer 12

Host cell materials. The outer surface of a virus contains antigens that a host cell may or not detect as foreign.

Question 13

Viral life cycle stages include?

Answer 13

infection of host cell, host cell enzymes replicate the viral genome which is transcribed and translated into viral proteins: new viral particles are assembled and released from host cells.

Question 14

Explain RNA retroviruses.

Answer 14

use the enzyme reverse transcriptase to form DNA which is then inserted into the genome of host cell allowing new viral particles to a formed.

Question 15

What is transmission?

Answer 15

Spread of parasite to a host.

Question 16

What is virulence?

Answer 16

Harm caused to a host species by a parasite.

Question 17

How are ectoparasites transmitted?

Answer 17

Direct contact or consumption of intermediate host.

Question 18

How are endoparasites transmitted?

Answer 18

By vectors.

Question 19

What factors increase transmission of parasites?

Answer 19

Overcrowding of hosts when they are at high density, vectors waterborne dispersal stages.

Question 20

Host behaviour is often modified by parasites to...

Answer 20

Maximise transmission.

Question 20

Alteration of what becomes part of the parasites extend phenotype?

Answer 20

Host foraging, movement, sexual behaviour, habitat choice or anti-predator behaviour.

Question 20

Parasites often suppress the hosts immune system and modify...

Answer 20

Host size and reproductive rate in ways that benefit parasite growth, reproduction or transmission.

Question 21

Name non-specific defences to parasites.

Answer 21

physical barriers (Skin and epithelial tissue), chemical secretion, inflammatory response, phagocytes and natural killer cells.

Question 22

Name chemical secretions.

Answer 22

Hydrolytic enzymes - mucus, saliva and tears - destroy bacteria cell walls. Stomach, sweat glads - low ph denature cellular proteins.

Question 23

What is phagocytosis?

Answer 23

Phagocytes use powerful enzymes contained in lysosomes by engulfing them and storing them inside a vacuole.

Question 23

How do natural killers work?

Answer 23

Identify and attach to cells to infected releasing chemicals that lead to apoptosis.

Question 24

If tissue damaged or invaded cells release cytokines that increase blood flow which increases what?

Answer 24

Non-specific and specific white blood cells accumulating at the site of infection.

Question 24

Mammals contain many different lymphocytes which have a receptor on their surface that can recognise a parasite antigen, if antigen binds to receptor what happens?

Answer 24

Lymphocyte divides and produces a clonal population of this lymphocyte.

Question 25

Some lymphocytes produce antibodies while others ....

Answer 25

Induce apoptosis.

Question 26

What happens when an antibody has antigen binded?

Answer 26

Antibody complex formed resulting in inactivation of parasite, making it susceptible to phagocyte or stimulate a response that results in lysis.

Question 27

Initial antigen exposure produces what?

Answer 27

Memory lymphocyte cells specific for that antigen that can produce a secondary response when same antigen renters

Question 28

In a secondary response, antibody production is enhanced in terms of...

Answer 28

Speed of production, concentration in blood and duration.

Question 29

Parasites have evolved ways of evading the immune system, endoparasites mimic host antigens to evade detection and modify immune response to avoid...

Answer 29

Destruction.

Question 29

Term for parasites changing between antigens during course of infection of a host and may also allow reinfection of same host with new variant.

Answer 29

Antigenic variation.

Question 30

Some viruses escape immune surveillance by integrating their genome into host genomes existing in an inactive state know as .....

Answer 30

Latency, virus emerges from latency when favourable conditions arise.

Question 31

What is the study of the outbreak and spread of infectious disease?

Answer 31

Epidemiology.

Question 32

What is the herd immunity threshold?

Answer 32

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

Question 33

Vaccines contain what?

Answer 33

Antigens that will elicit an immune response

Question 34

What makes designing parasite difficult?

Answer 34

Some parasites are hard to culture in lab.

Question 34

Similarities between what make it difficult to find drug compounds that only target parasite?

Answer 34

Host and parasite metabolism.

Question 34

What has to be reflected in the design of vaccines?

Answer 34

Antigenic variation.

Question 35

Explain overcrowding and parasite.

Answer 35

Can occur in refugee camps that results from war or natural disasters or rapidly growing towns in LEDC. These conditions make coordinated treatment and control programmes difficult to achieve.

Question 36

what are the practical parasite control strategies?

Answer 36

Civil engineering to improve sanitation and co-ordinated vector control.

Question 37

Improvements in parasite control does what for the youth?

Answer 37

Reduces child mortality, results in population-wide improvements in child development and intelligence as individuals have more resources for growth and development.