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Biology A Level > Populations > Flashcards

Populations Flashcards

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1
Q

Habitat vs. Niche

A

Habitat - an area where an organism lives

Niche - exact role an organism plays in its habitat, including all the abiotic and biotic conditions required for the organism to survive and reproduce

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2
Q

Fundamental niche

A
  • aka -> potential niche
  • where it is possible for an organism to survive
  • determined by abiotic factors
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3
Q

Realised niche

A
  • aka -> actual niche
  • where an organism actually survives
  • reduces volume than the fundamental niche due to competition
  • determined by abiotic and biotic factors
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4
Q

Competitive exclusion principle

A
  • no two organism of different species can occupy the same niche indefinitely
  • complété competitors cannot exist
  • results in niche separation, to avoid competitive advantages
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5
Q

MRR

A
  • allocate an area with a defined boundary
  • capture a group of individuals and tag with a non-invasive, non-toxic market that would not result in any disadvantage to the organism
  • reintroduce into population and allow enough time for even distribution
  • capture another sample and count the number of tagged organisms
  • déterminé population using Lincoln-Peterson Index
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6
Q

Lincoln-Peterson index

A
  • multiply samples 1 and 2
  • divide by the number of tagged individuals recaptured
  • population estimate
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7
Q

Abiotic limiting factors on population

A
  • temperature
  • pH
  • light
  • humidity
  • wind speed
  • tidal range
  • wave/water speed
  • viral infection
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8
Q

Biotic limiting factors on population

A
  • intraspecific competition
  • interspecific competition
  • predation
  • bacterial disease
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9
Q

Sampling

A
  • representation (proved accurate by statistical testing)

* affected by change (REPEAT) and bias (RANDOM)

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10
Q

Use systematic sampling for

A

Gradual change in conditions

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11
Q

Picking a quadrat

A
  • species size
  • evenness of distribution
  • rarity of species
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12
Q

How does temperature affect carrying capacity?

A
  • optimum for enzymes
  • réduction in plant metabolic rate
  • dénaturation
  • higher homeostatic energy expenses; less energy for growth, maturation and reproduction
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13
Q

How does light affect carrying capacity?

A
  • ultimate energy source for most ecosystems; basic necessity of life
  • rate of photosynthesis increases with light intensity
  • rate of growth and spore production increases with rate of photosynthesis
  • increases plant and plant-eating carrying capacities
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14
Q

How does pH affect carrying capacity?

A

• any deviation from optimum means carrying capacity is tiny

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15
Q

How does water affect carrying capacity?

A
  • lack of aquatic creatures

* only organisms adapted to dry conditions can survive

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16
Q

How does humidity affect carrying capacity?

A

• transpiration and evaporation affected

17
Q

When abiotic conditions shift from optimum

A

Population sizes decrease- species without suitable adaptations become extinct (barring evolution through advantageous alleles)

18
Q

Human population

A

• affected by natality, mortality, immigration and emigration

19
Q

Population pyramids

A
  • a series of stacked bars representing percentages of males and female in each age group
  • useful because population growth depends on females of child-bearing age
  • product future trends for populations
  • show demographic transitions
20
Q

Increasing populations

A
  • base of population pyramid is higher than the apex

* typical of less economically developed countries

21
Q

Competition

A

Arises from insufficient resources to fully satisfy the requirements of two individuals sharing

22
Q

Availability of resources

A

Determines population size

23
Q

Predation

A
  • interspecific relationship

* consumption of one consumer with another

24
Q

Predator

A
  • a consumer that feeds on another (prey)

* evolved speed and camouflage

25
Q

Prey

A
  • a consumer consumed by another

* evolves canouflage, protective features and concealment behaviour

26
Q

Predators and prey….

A

Evolve alongside each other, otherwise extinction would occur, which is rare

27
Q

Prey escape due to

A
  • greater area for travel
  • potential refugee
  • not being the only predated species
28
Q

Describe the predator-prey graph

A
  • predators consume prey, reducing their population
  • greater intraspecitic competition between predators
  • predators population decreases due to inability to survive and reproduce
  • there are cyclic fluctuations in populations
  • periodic population crashes influence evolution by creating selective pressures
29
Q

Succession

A

Changes experiences by dynamic ecosystems due to population fluctuations

30
Q

Succession stages

A
  • colonisation of différent species, changing the abiotic conditions
  • results in out-competition due to adaptations
  • forms new community, altering biodiversity
31
Q

Pioneer species

A
  • colonise an inhospitable environment
  • forma pioneer community
  • use photosynthesis
  • have wind-dispersed seeds or spores that undergo rapid germination without dormancy
  • fix nitrogen
  • xérophytic
32
Q

Climax community

A
  • many species flourish - relatively high biodiversity

* stable over long periods

33
Q

Ramifications of stages of succession

A
  • decrease is hostility of abiotic conditions
  • proliferation of habitat and niche number
  • increases biodiversity (decreases slightly with climax community with out competition of pioneer species)
  • more complex food we’ve
  • higher biomass
34
Q

Secondary succession

A
  • disruption of climax community by abiotic factors
  • succession stages begin again
  • faster due to established hospitality

Biology A Level (45 decks)

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