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Unit 3 Biology > Population Size and Ecosystems > Flashcards

Population Size and Ecosystems 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
Herbivores
Trophic level 2 Animals which feed on organic matter from producers
26
Carnivores
Feed on other animals at lower levels
27
Trophic level
Position in a food chain
28
Detritivores
Feed on dead organic matter e.g. earthworms
29
Decomposers
Break down organic compounds into simpler inorganic compounds to be absorbed by plant roots e.g. bacteria
30
How is energy lost?
Light is reflected from leaf surface Wrong wavelength of light which cannot be absorbed by pigments Light passes through leaf
31
How is most energy lost by producers?
Lost as heat from respiration
32
Why is a lot of energy from herbivores not used?
Cellulose in plant cell walls cannot be digested and is lost as waste for decomposers
33
GPP
Gross primary productivity Rate of production of chemical energy in biological molecules by photosynthesis Most used during respiration and some lost as heat
34
NPP
Net primary productivity Energy in plant biomass which could pass to the primary consumers at level 2 at feeding
35
Calculating NPP
GPP - R = NPP
36
Secondary productivity
Rate at which heterotrophs accumulate energy in the form of new cells and tissues
37
Calculating the efficiency of energy transfer
Energy into biomass after transfer / energy available before transfer x 100
38
Ecological pyramids
Represent food chains: the base is primary producer, and the top is consumer
39
Succession
Sequence of changes in a community over time eventually leading to a stable climax community which has high biodiversity and productivity
40
Sere
Each stage of succession
41
Primary succession
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
Secondary succession
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
Process of carbon cycle
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
Ways human activity is disturbing carbon cycle
Deforestation, burning fossil fuels, increase in decomposition
45
What does increase CO2 lead to?
Enhanced greenhouse effect, global warming, driving climate change. Melting ice caps, sea levels rising, increased extreme weather, desertification, soil erosion, extinction, dieases
46
Carbon footprint
Total amount of CO2 produced directly due to actions of an individual per year
47
How can we reduce carbon footprint?
Produce less meat - land resources and feed Crops grown for humans not feed Packaging reduced Transport distances reduced Food produced locally
48
Nitrogen cycle definition
Flow of inorganic and organic nitrogen in the abiotic and biotic elements of an ecosystem
49
Nitrogen fixing
Fixing atmospheric nitrogen into ammonia
50
Nitrification
Converting products of decay into nitrate ions
51
Azotobacter
Free-living bacteria in soil. Aerobic and fixes nitrogen gas to ammonium ions
52
Rhizobium
In root nodules of legumes and shares symbiotic relationship. Uses nitrogenase to fix gas into soluble ammonium
53
Nitrosomonas
Free living aerobic bacteria, convert ammonium to nitrite
54
Nitrobacter
Free living aerobic bacteria, converts nitrite to nitrate which is absorbed into plant root hair by active transport
55
Denitrification
Loss of soluble nitrate compounds
56
Process of nitrogen cycle
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
Human activities improving availability of nitrate
Adding chemical fertilisers (ammonium nitrate) Adding manure (animal waste) Adding treated sewage (human waste) Planting legumes Ploughing or draining to improve aeration
58
Human activity causing nitrogen pollution
Excess nitrates on grasslands leads to weeds, reduced biodiversity, competition Draining wetlands destroys habitats Nitrate pollution causes eutrophication
59
Eutrophication
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 (8 decks)

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