Biology > Ecosystems* > Flashcards

Ecosystems* Flashcards

(53 cards)

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1
Q

What is ecology

A

Study of relationships between organisms and their environment

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2
Q

What is an ecosystem

A

Consists of all the living things in a specific area, along with the non living physical components they interact with

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3
Q

Examples of biotic factors

A

Number of types of plants & animals
Competition among organisms for food, territory, mates
Dynamics of predator and prey relationships
Diseases/parasites

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4
Q

Why does light intensity affect ecosystems

A

Influences growth & behaivour of photosynthetic organisms

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5
Q

Why does temp affect ecosystems

A

Affects activity of enzymes that regulate metabolic and reproductive activities

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6
Q

Why does water availability affect ecosystems

A

Critical for cell activities, maintaining cell osmotic balance and photosynthesis

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7
Q

Why does O2 availability affect ecosystems

A

Vital for survival of aerobic organisms as they need it to release energy

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8
Q

Why does soil type affect ecosystems

A

Influences soils drainage capabilities and the nutrients it can offer to organisms

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9
Q

List the abiotic factors affecting ecosystems

A

Light intensity
Temperature
Water availability
Soil type
Oxygen availability

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10
Q

What are producers

A

Organisms that make their own food eg photosynthesising plants

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11
Q

What are primary consumers

A

Herbivores that consume producers

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12
Q

What are secondary consumers

A

Organisms consume primary consumers

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13
Q

What are tertiary consumers

A

Organisms consume secondary consumers for food

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14
Q

What are saprobiants

A

Decomposes - decompose complex materials in dead organisms into simpler substances to obtain their food and release nutrients back into the ecosystem

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15
Q

Describe a food chain vs a food web

A

Food chain = sequence of organisms connected by feeding
Food web = complex network of interconnected food chains within ecosystem

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16
Q

What is biomass

A

Total mass of living material present at particular time in specific place/within certain organisms

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17
Q

What is biomass measured in on land

A

g m ^-2

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18
Q

What is biomass measured in in aquatic environments

A

g m ^-3

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19
Q

How can the energy stored in biomass be measured

A

Calorimetry:
1. Dry biomass sample until mass remains constant to obtain dry mass
2. Weigh dry mass
3. Burn dry mass in calorimeter
4. Measure vol&temp change of surrounding water
5. Use these values to calculate estimate of heat energy released from burnt biomass

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20
Q

Formulae for calculating net primary production

A

Gross primary production - respiratory losses

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21
Q

What factors contribute to energy losses between trophic levels

A

Not all solar energy is captured by leaves
Water availability can limit photosynthesis
Energy lost during photosynthetic reactions
Not all parts of biomass edible/digestible by consumers
Energy lost as heat during movement/respiration
Energy lost in excretory materials eg urine/faeces

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22
Q

How can agriculture manipulate transfer of biomass through ecosystems

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A

Manipulate environmen to favour crops & rear animals for food (e.g. small space so less movement)

23
Q

Formula for calculating ecological efficiency

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A

(Biomass available after transfer/biomass available before)
X 100

24
Q

What % of the atmosphere is nitrogen gas

25
What is the purpose of the nitrogen cycle
Transforms nitrogen gas into chemical forms that organisms can use
26
What are the 4 key processes of the nitrogen cycle
Nitrogen fixation Ammonification Nitrification Denitrification
27
What does nitrogen fixation do
Converts nitrogen gas into ammonia
28
What bacteria are involved in nitrogen fixing
Rhizobium Azotobacter
29
What is rhizobium
Nitrogen fixing bacteria Mutualistic bacteria in root nodules of leguminous plants
30
How is the relationship between leguminous plants and rhizobium mutualistic
Ammonia can be converted into amino acids for plant Plant provides carbs to bacteria
31
What is ammonification
Converts nitrogen compounds in dead organisms into waste substances eg ammonium ions/ammonia
32
How does ammonification make ammonia available to plants
Death/excretion by living organisms releases nitrogen-rich organic substances Saprobionts decompose these into smaller substances eg ammonia Ammonia can be absorbed&assimilated by plants
33
What is nitrification
Ammonia oxidised to nitrites (NO2-) then nitrates (NO3-)
34
Which bacteria are involved in nitrification and which stage are they involved in
Nitrosomonas - oxidise ammonium compounds into nitrites Nitrobacter - further oxidise nitrites into nitrates (NO2- into NO3-)
35
What does denitrification do
Converts nitrate back into nitrogen gas
36
What can excessive denitrification lead to
Deplete soil nitrogen, negatively impacting plant growth
37
How does denitrification convert nitrates into atmospheric nitrogen
Carried out by denitrifying bacteria Occurs under anaerobic conditions e.g., waterlogged soils
38
What key processes are involved in the carbon cycle
Photosynthesis Consumption Respiration Decomposition Formation of fossil fuels Combustion Weathering Volcanic activity
39
What causes daily fluctuations in atmospheric CO2
Respiration (release) Photosynthesis (remove) during daylight
40
What causes seasonal fluctuations in atmospheric CO2
Summer - long daylight hours = more photosynthesis = reduced CO2 Winter - reduced daylight hours & cold temps = less photosynthesis = more CO2
41
What causes annual fluctuations in atmospheric CO2
Annual increase of greenhouse gas emissions Increased deforestation Burning biomass of trees from deforestation Global warming
42
How does global warming affect CO2 levels in the atmosphere
Rising conc of CO2 accelerates global warming This decreases solubility of CO2 in oceans as less gas can dissolve in warmer water = more CO2 released into atmosphere
43
What is succession
Process by which ecosystems change over time due to changes in the environment As environmental conditions change, different species can colonise, outcompete & replace species that were there previously
44
What is primary succession
Occurs on newly formed/exposed land with no soil/ organic material E.g., fresh volcanic lava
45
What is secondary succession
Occurs where an existing community has been removed, leaving soil intact but no plant/ animal species E.g., area that has experienced a forest fire
46
What are the stages of succession
1. Initial colonisation by pioneer communities 2. Alteration of conditions by pioneer species (help soil formation) 3. Settlement by intermediate communities (move in when soil improves&continue to modify environment) 4. Diversification of intermediate communities (variety of species grow, larger&more complex organisms grow) 5. Development of climax communities
47
What is a climax community
Stable ecosystems with a balanced equilibrium of species, characterised by small no. Of dominant plant&animal species rarely replaced by new species
48
What are the typical adaptations of pioneer communities
Ability to reproduce asexually Seeds dispersed by the wind Rapid germination Ability to photosynthesise Nitrogen fixation to enrich soil Extreme condition tolerance
49
When does deflected succession occur
When human activity interrupts the normal sequence of succession, preventing the ecosystem from reaching its natural climax community Final state = plagioclimax
50
Give examples of human actions that can cause deflected succession
Continuous grazing/trampling by domesticated animals & livestock Clearing native vegetation for planting crops Burning land to clear forests
51
What are the limitations of using quadrants for measuring animal abundance
Most animals are mobile & don’t remain in fixed area Slow moving animals counted but fast moving missed May not give representative sample as individuals move in & out
52
Give the steps in using the mark-release-recapture technique
1. Capture sample of individuals from target population in defined area 2. Mark/tag each captured individual in some way 3. Release marked back into original habitat 4. Allow time for marked to mix evenly throughout population 5. Recapture another sample in same area 6. Record no. Of marked & unmarked individuals in second sample 7. Use Lincoln index to estimate total population size
53
What are the assumptions made of the mark release recapture technique
Marked individuals distribute evenly among rest of population Population remains constant - no significant immigration, births, deaths Population has definite boundary Marks are non toxic and don’t increase predation rates/change behaivour Marks are permanent & cannot be lost
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