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Unit 3 Biology > Population Size and Ecosystems > Flashcards

Population Size and Ecosystems Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Population

A

A group of organisms of a single species interbreeding and occupying an area

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2
Q

Factors determining population size

A

Birth rate, death rate, immigration, and emigration

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3
Q

Fugitive species

A

Cannot tolerate competition. To increase, they reproduce rapidly and have effective spreading. They invade new environments fast. e.g. weeds.

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4
Q

Equilibrium species

A

Control population by competition. They have an S shaped one-step growth curve. e.g. rabbits.

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5
Q

Lag phase for bacteria

A

Bacteria adapt to new environment and prepare for growth

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6
Q

Log phase for bacteria

A

Bacterial cells replicate exponentially. No limiting factors.

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7
Q

Stationary phase for bacteria

A

Bacterial growth levels off as cell death = new cells. Factors such as nutrient supply become limiting and waste builds up.

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8
Q

Death phase for bacteria

A

Cell death exceeds cell division. Waste products have reached toxic levels that stop growth.

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9
Q

Abiotic factors

A

Non living factors e.g. temperature, light, pH, water

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10
Q

Biotic factors

A

Living factors e.g. competition, disease, predation

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11
Q

Carrying capacity

A

Maximum population size of a species that an environment can sustain.

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12
Q

Population crash

A

Sudden dramatic decrease in population, when a population greatly exceeds carrying capacity

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13
Q

Equation for population growth

A

B+I=E+D

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14
Q

Why is bacterial growth plotted on a log scale?

A

The numbers are too large for a linear scale

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15
Q

Density dependent factors

A

The effect of density dependent factors increases as the population increases.
Biotic factors - living
e.g. competition, predation, disease
Determine carrying capacity

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16
Q

Density independent factors

A

Abiotic factors - non living
Not linked to population density
e.g. earthquakes, tsunami, wildfires

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17
Q

Abundance

A

Number of individuals of same species in an area

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18
Q

Capture-mark-recapture

A

Organisms trapped and marked then release. The same sampling occurs a day later.
Pop size = day 1 total x day 2 total / marked in day 2

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19
Q

Random sampling

A

Using a quadrat to find density of organisms in an area

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20
Q

Systematic sampling

A

Using a transect to determine changes in percentage cover of species due to changes in abiotic factors e.g. light intensity

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21
Q

Niche

A

Its role in an ecosystem

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22
Q

Ecosystem

A

A characteristic community of interdependent species and their habitat

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23
Q

Producers

A

Trophic level 1
Autotrophic organisms which absorb light energy

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24
Q

Consumers

A

Heterotrophic organisms that ingest it or absorb from other organisms

25
Q

Herbivores

A

Trophic level 2
Animals which feed on organic matter from producers

26
Q

Carnivores

A

Feed on other animals at lower levels

27
Q

Trophic level

A

Position in a food chain

28
Q

Detritivores

A

Feed on dead organic matter e.g. earthworms

29
Q

Decomposers

A

Break down organic compounds into simpler inorganic compounds to be absorbed by plant roots e.g. bacteria

30
Q

How is energy lost?

A

Light is reflected from leaf surface
Wrong wavelength of light which cannot be absorbed by pigments
Light passes through leaf

31
Q

How is most energy lost by producers?

A

Lost as heat from respiration

32
Q

Why is a lot of energy from herbivores not used?

A

Cellulose in plant cell walls cannot be digested and is lost as waste for decomposers

33
Q

GPP

A

Gross primary productivity
Rate of production of chemical energy in biological molecules by photosynthesis
Most used during respiration and some lost as heat

34
Q

NPP

A

Net primary productivity
Energy in plant biomass which could pass to the primary consumers at level 2 at feeding

35
Q

Calculating NPP

A

GPP - R = NPP

36
Q

Secondary productivity

A

Rate at which heterotrophs accumulate energy in the form of new cells and tissues

37
Q

Calculating the efficiency of energy transfer

A

Energy into biomass after transfer / energy available before transfer x 100

38
Q

Ecological pyramids

A

Represent food chains: the base is primary producer, and the top is consumer

39
Q

Succession

A

Sequence of changes in a community over time eventually leading to a stable climax community which has high biodiversity and productivity

40
Q

Sere

A

Each stage of succession

41
Q

Primary succession

A

Begins with bare rock. First organisms to colonise are pioneer species (lichens, mosses)
Pioneer species penetrate rock, forming cracks, allowing humus to build up, allows grasses and ferns to colonise
Grasses and ferns change rock as roots penetrate further and deeper, death and decay allows more soil and plants to invade
Increase biodiversity and stability
Climax community

42
Q

Secondary succession

A

Begins with bare soil from wildfire
Achieved much faster as soil is already present, containing seeds and spores.
Human activity can prevent climax community e.g. farming of land, deforestation, soil erosion

43
Q

Process of carbon cycle

A

CO2 from atmosphere fixed into carbohydrate by photosynthesis
Respiration releases CO2
Combustion releases carbon in form of CO2
Decomposition releases CO2 due to respiration
Deforestation increases CO2 in atmosphere

44
Q

Ways human activity is disturbing carbon cycle

A

Deforestation, burning fossil fuels, increase in decomposition

45
Q

What does increase CO2 lead to?

A

Enhanced greenhouse effect, global warming, driving climate change.
Melting ice caps, sea levels rising, increased extreme weather, desertification, soil erosion, extinction, dieases

46
Q

Carbon footprint

A

Total amount of CO2 produced directly due to actions of an individual per year

47
Q

How can we reduce carbon footprint?

A

Produce less meat - land resources and feed
Crops grown for humans not feed
Packaging reduced
Transport distances reduced
Food produced locally

48
Q

Nitrogen cycle definition

A

Flow of inorganic and organic nitrogen in the abiotic and biotic elements of an ecosystem

49
Q

Nitrogen fixing

A

Fixing atmospheric nitrogen into ammonia

50
Q

Nitrification

A

Converting products of decay into nitrate ions

51
Q

Azotobacter

A

Free-living bacteria in soil. Aerobic and fixes nitrogen gas to ammonium ions

52
Q

Rhizobium

A

In root nodules of legumes and shares symbiotic relationship. Uses nitrogenase to fix gas into soluble ammonium

53
Q

Nitrosomonas

A

Free living aerobic bacteria, convert ammonium to nitrite

54
Q

Nitrobacter

A

Free living aerobic bacteria, converts nitrite to nitrate which is absorbed into plant root hair by active transport

55
Q

Denitrification

A

Loss of soluble nitrate compounds

56
Q

Process of nitrogen cycle

A

Decomposers break down molecules into ammonium
Nitrosomonas converts ammonia to nirite then nitrobacter converts it to nitrate - nitrification
Inorganic nitrogren sources converted to gas by pseudomonas - denitrification
Azotobacter and rhizobium fix gas to ammonia - nitrogen fixing
Nitrates absorbed by root hair by active transport, requires ATP

57
Q

Human activities improving availability of nitrate

A

Adding chemical fertilisers (ammonium nitrate)
Adding manure (animal waste)
Adding treated sewage (human waste)
Planting legumes
Ploughing or draining to improve aeration

58
Q

Human activity causing nitrogen pollution

A

Excess nitrates on grasslands leads to weeds, reduced biodiversity, competition
Draining wetlands destroys habitats
Nitrate pollution causes eutrophication

59
Q

Eutrophication

A

Fertilisers washed into rivers, causes algal blooms to form, covering surface of water, reducing oxygen for organisms under, plants and animals die, encourages denitrifying bacteria to form, decreasing nitrate levels

Unit 3 Biology (3 decks)

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