Unit 2 KA5

Question 1

ai

ecological niche

Answer 1

multi-dimensional summary of tolerances and requirements of a species

Question 2

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what is a fundamental niche

Answer 2

where a species occupoes in absence of interspecific competition

Question 3

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what is a realised niche

Answer 3

is occupied in response to interspecific competition

Question 4

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competitive exclusion

Answer 4

where the niches of 2 species are so similar that one declines to total distinction
result of interspecific competition

red and grey squirrel

Question 5

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what happens when the realised niches are sufficiently different

Answer 5

potential competitors can co-exist by resource partitioning

Question 6

aii

what is parasitism

Answer 6

symbiotic interation between a parasite and its host (+/-)
a parasite gains benefit in terms of nutrients at the exprense of its host

Question 7

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compared to the host, what is the reproductive potential of the parasite?

Answer 7

greater (unlike predator-prey relationship)

Question 8

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what can the niches of parasites be described as?

Answer 8

narrow, specialised and host specific

Question 9

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why are many parasites degenerate

Answer 9

host provides much of parasites needs so they lack structure

Question 10

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ectoparasite

definition and transmission

Answer 10

surface of host
generally transmitted through direct contact

Question 11

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endoparasite

definition and transmission

Answer 11

inside host
often transmitted by vectors or by consumption of intermediate hosts

Question 12

b

definitive host

Answer 12

organism on/in which the parasite reasches sexual maturity

Question 13

b

intermediate host

Answer 13

required to complete its life cycle

Question 14

b

vector

Answer 14

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

Question 15

b

key steps to plasmodium

Answer 15

• infected mosquito (vector) bites human
• P enters blood
• Asexual reproduction occurs in the liver and then in RBC
• RBC burst, gametocytes are released into blood
• another mosquito bites infected human
• gametocytes enter m
• sexual reproduction occurs in mosquito

Question 16

b

key steps of schistosomiasis (s)

Answer 16

• schistosomes reproduce sexually in the human intestine
• fertilised eggs pass out via faeces into water where they develop into larvae
• larvae infect water snails where asexual reproduction occurs
• produces another type of motile larvae, these escape the snail
• penatrate skin of human and enter bloodstream

Question 17

b

viruses

Answer 17

• parasites that can only replicate inside a host cell
• contain genetic material (DNA/RNA) which are packaged in a protective protein coat
• some are surrounded by a phospholipid membrane from host cell materials
• outer surface of virus contains antigens that a host cell may/may not be able to detect as foreign

Question 18

b

virus life cycle stages

Answer 18

• infection of host cell with genetic material
• host cell enzymes replicate viral genome
• transcription of viral genes and translation of viral proteins
• assembly and release of new viral particles

Question 19

b

RNA retroviruses

Answer 19

use enzyme reverse transcriptase to form DNA
this is inserted into the genome of the host cell

Question 20

b

what can viral genes can be expressed to form?

Answer 20

new viral particles

Question 21

c

transmission

Answer 21

spread of a parasite to a host

Question 22

c

virulence

Answer 22

harm caused to a host species by a parasite

Question 23

C

factors that increase transmission rates

Answer 23

1. overcrowding
2. mechanisms such as: vectors, waterborne dipersal stages

Question 24

c

why is host behaviour ofen exploited and modified by parasites?

examples

Answer 24

to maximise transmission
examples;
alteration of host foraging, movement, sexual behaviour

Question 25

# c what does the host behaviour become a part of?

Answer 25

extended phenotype of the parasite

Question 26

# c what does the parasites often suppress? why?

Answer 26

* host immune system * modify host size * reproductive rate all to benefit **parasite growth, reproduction and transmission**

Question 27

# d non-specific defences

Answer 27

physical barriers, chemical secretions, inflammatory response, phagocytes, natural killer cells

Question 28

# d how exactly do these nonspecfic defences defend against immunological attacks

Answer 28

* *epithelial tissue* **blocks the entry of parasites** * hydrolytic enzymes in *mucus, saliva and tears,* **destroy bacterial cell walls** * low pH secretions of *stomach,vagina and sweat* glands **denatures cellular proteins and pathogens**

Question 29

# d what happens in the inflammitory response

Answer 29

non-specific- first line of defense * injured cells release signalling molecules * results in **enhanced** blood flow to site with antimicrobial proteins and phagocytes

Question 30

# d how can parasites be killed?

Answer 30

by using powerful enzymes contained in **lysosomes**, by engulfing them and storing them inside a vacuole in the **process of phagocytosis**

Question 31

# d in the non-specific first line of response, how do natural killer cells help fight off immunilogical defences

Answer 31

can identify and attach to cells infected with viruses, releasing chemicals that lead to cell death by inducing apoptosis

Question 32

# d specific cellular defences

Answer 32

this is where a range of white blook cells constantly circulate, monitoring the tissues

Question 33

# d what happens if tissues become damaged or invaded in the specific cellular defences

Answer 33

cells release cytokines that increase blood flow, refulting in non-specific and specific white blood cells accumulating at the site of infection or tissue damage

Question 34

# d lymphocytes

Answer 34

mammals contaim many different types each possesses a receptor on its surface which can potentially recognise a parasite antigen

Question 35

# d binding of an antigen to a lymphocyte's receptor does what?

Answer 35

so the lymphocyte can then divide and produce a clonal population of this lymphocyte some will produce antibodies ans others can induce apoptosis in parasite infected cells

Question 36

# d antibodies

Answer 36

possess regions where the amino acid sequence varies greatly between different antibodies this variable region gives the antibody its specificty for binding antigen

Question 37

# d What is the result of the antigen-antibody complex formed

Answer 37

* inactivation of the parasite * making it suseptible to a phagocyte * stimulate a response that results in cell lysis * memory lymphocyte cells are also formed

Question 38

# d what can initial antigen exposure produce

Answer 38

* memory lymphocyte cells specific for that antigen * can produce secondary rresponse when the same antigen enters the body in the future * when this occurs antibody production is enhancd in terms of **speed of production, concentration in blood and duration**

Question 39

# e in terms of immune evasion, what do endoparasites do?

Answer 39

mimic host antigens to evade detection and modify host immune response to reduced their chances of destruction

Question 40

# e what does antigenic variation allow some parasites to do?

Answer 40

to change between different antigens during the course of infection of a host may also allow reinfection of the same host with the new variant

Question 41

# e how do some viruses escape immune surveillence

Answer 41

by integrating their genome into host genomes, existing in an inactive state knoen as latency virus becomes active again when favourable conditions arise

Question 42

# f epidemiology

Answer 42

study of the outbreak and spread of infectious disease

Question 43

# f herd immunity threshold

Answer 43

density of resistant hosts in the population required to revent an epidemic

Question 44

# f why do vaccines contain antigens

Answer 44

so they can produce an immune resonse that can be replicated in the future if host comes across infection

Question 45

# f in what ways is it difficuls to design a drug

Answer 45

* similarities between host and parasite metabolism (hard to target only parasite) * antigenic variation ahs to be reflected in the design of vaccines * some parasites are difficult to culture in the lab

Question 46

# f where do parasites spread most rapidly

Answer 46

* overcrowding (in refugee camps) * tropical climates | these make co-ordinated treatment&control programs difficult to achieve

Question 47

# f name some practical control strategies for parasitism

Answer 47

* civil engineering projects to improve sanitation * coordinated vector control (mosquito nets)

Question 48

# f improvments in parasite control does what?

Answer 48

reduce child mortality and results in population-wide improvemtns in child development and intelligence as individuals have more resourses for growth and development