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biology year 2 > Population in Ecosystems > Flashcards

Population in Ecosystems Flashcards

1
Q
A
  • intraspecific competition
  • compete with fertile males to mate
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2
Q

describe how the mark-release-recapture method could be used to determine the population of A.aegypti at the start of the investigation?

A
  • capture, mark and release
  • leave time for mosquitoes to disperse before second sampling
  • population size = no. caught in 1st sample x no. caught in 2nd sample / number marked in second sample
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3
Q

the release of radiation-sterilised A.aegypti has not been very successful in controlling the transmission of dengue.

suggest why?

A

radiation affects attractiveness of A.aegypti

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4
Q

suggest why the scientists released more transgenic males every week?

A
  • maintain competition
  • as more transgenic males die
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5
Q

the release of transgenic males proved successful in reducing the number of A.aegypti.

describe how the results in the figure support this conclusion?

A

number lower after 12 weeks

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6
Q

define habitat?

A

place where an organism lives

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7
Q

define population?

A

all the organisms of one species in a habitat

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8
Q

define community?

A

populations of diff species in a habitat

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9
Q

define ecosystem?

A

a community, plus all the non-living condtions in the area in which it lives.

can be small/large

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10
Q

define abiotic conditions?

A

non-living features of the ecosystem

e.g. temp, availability of water

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11
Q

define biotic conditions?

A

living features of ecosystem

e.g. presence of food / predators

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12
Q

define niche?

A

role of a species within its habitat

e.g. what it eats, where and when it feeds

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13
Q

define adaptation?

A

a feature that members of a species have that increases their chance of survival and reproduction

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14
Q

the niche a species occupies within its habitat includes what?

A
  • biotic interactions - organism eats, what its eaten by
  • abiotic interactions - oxygen breathes in, CO2 breathes out
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15
Q

every species has its own unique…

A

niche

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16
Q

if 2 species try to occupy the same niche, what happens?

A
  • will compete
  • one species more successful than other
  • until one species left
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17
Q

define natural selection?

A

organisms with better adaptations more likely to survive, reproduce and pass on favourable allele

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18
Q

adaptations to abiotic conditions?

A
  • otters have webbed paws - can walk and swim - can live and hunt on land and water
  • seals have thick layer blubber - keeps them warm in coldest seas - can live in places where food plentiful
  • hedgehogs hibernate - lowers metabolism rate - conserve energy during cold months
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19
Q

adaptations to biotic conditions?

A
  • sea otters use rocks smash open shellfish and clam - gives access to another source of food
  • male frogs prod mating calls - attract mate of same species - successful mating more likely
  • bacteria prod antibiotics - kill other species of bacteria in same area - less competition
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20
Q

define population size?

A

total number of organisms of one species in habitat

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21
Q

define carrying capacity?

A

maximum stable population size of a species that an ecosystem can support

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22
Q

list some abiotic factors?

A
  • light
  • water
  • space
  • temp
  • chemical composition
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23
Q

what is interspecific competition?

A

when organisms of different species compete with each other for same resources

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24
Q

what can interspecific comp lead to ?

A
  • resources available to both species reduced
  • pop limited by lower amount of food
  • less energy for growth and reproduction
  • populations smaller
25
if 2 species are competing but one is better adapted to its surroundings than other, what happens?
less well adapted OUTCOMPETED
26
how does the grey squirrel have a better chance of survival?
- larger - store more fat - eats wider range of food
27
what is intraspecific competition?
when organisms of **same species** compete with each other for same resources
28
what can intraspecific comp lead to?
- pop inc when resources plentiful - more organisms competing for same amount of space and food - resources = limiting - pop declines - smaller pop = less comp - better for growth and reprod
29
what is predation?
where organism kills and eats another organism
30
the population sizes of predators and prey are interlinked. how?
as population of one changes, causes other population to change
31
describe the predator-prey relationship?
- prey pop inc - more food for pred, pred pop inc - more prey eaten, prey pop dec - less food for pred - pop dec
32
what are non-motile organisms?
organisms that dont move about e.g. plants
33
what are quadrats?
square frame divided into a grid
34
how are quadrats used?
placed on ground at random diff points in area
35
define species frequency?
how often species found / number of individuals of each species reacorded in each quadrat
36
how can percentage cover be found?
counting how much quadrat covered by species
37
what is percentage cover a quick way of?
investigating pop
38
to cover larger distances, what can you do?
quadrats places at intervals along line (interrupted belt transects)
39
mark-release-recapture method?
- capture sample of species - mark in harmless way - release back into habitat - wait week, take 2nd sample - count how many of 2nd sample marked TOTAL POP SIZE = NUMBER CAUGHT IN **1ST** SAMPLE X NUMBER CAUGHT IN **2ND** SAMPLE / NUMBER **MARKED** IN **2ND** SAMPLE
40
what are the assumptions you have to make in the mark-release-recapture method?
- sample had enough time and opportunity to mix back in with pop - marking not affected individuals' chance of survival - no change in pop size due to births, deaths and migration
41
investigating the effect of soil pH on marram grass in coastal ecosystem?
- place **tape measure** in straight line from shore heading inland ## Footnote - take 1m^2 quadrat divided into 100 squares - starting from shore, place quadrat next to tape measure - **count** squares containing marram grass and record result in table as **percentage cover** - at each sample point, measure **pH** and record - **repeat** every 10m along line
42
how can you measure pH?
- use digital probe OR - take sample - add barium sulfate, distilled water and pH indicator - shake - compare colour against pH chart
43
why does pH inc near shore?
- sand/soil contain shell fragments - made of calcium carbonate - alkaline
44
why does pH dec as you move inland?
rotting veg adds organic matter to soil = acidic
45
safety issues?
- local tide times - suitable clothing and footwear - wash hands before eating
46
ethical issues?
- people trample on marram grass - erosion
47
define succession?
process by which an ecosystem changes over time
48
primary succession?
- happens on newly formed / exposed land - no soil / organic material
49
secondary succession?
- happens on cleared land - e.g. deforested land - soil remains
50
define pioneer species?
first species to colonise an area
51
process of primary succession?
- **pioneer species colonise** rocks e.g. lichens grow on & break down rocks --\> rel minerals - lichens die, and decompose = thin soil - thickens as more organic material formed - other species e.g. moss can grow - larger plants need more water - move in as soil deepens - soil deepen as larger plants die and decompose - larger plants grow and **out-compete** smaller plants = dominant species - **biodiversity inc** - soil deep and rich enough in nutrients to support large trees - **climax community** formed
52
process of secondary succession?
- happens in same way as primary - already soil layer - starts later - pioneer species = larger plants e.g. shrubs
53
what is the final stage of succession called?
climax community
54
define climatic climax?
climax community for a particular climate
55
define plagioclimax?
when succession stopped artificially
56
what are the ways to manage succession to conserve the moorland ecosystem?
- animals allowed graze on land - similar to mowing - animals eat growing points of shrubs and trees --\> stops establishing themselves - keeps veg low - managed fires lit - secondary succession occurs after fire - pioneer species conserved
57
define conservation?
protection and management of species and habitats in a sustainable way
58
define sustainable?
enough resources are taken to meet needs of people today, without reducing ability of people in future to meet their own needs

biology year 2 (29 decks)

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