2.3 flows of energy and matter

Question 1

Explain the pathways of solar radiation as it passes through the atmosphere

Answer 1

1. Direct Transmission: Solar radiation that travels directly from the Sun to the Earth’s surface without being scattered or absorbed
2. Scattering: solar radiation interacts with atmospheric gases, changing direction
3. Absorption: some solar radiation is absorbed by atmospheric gases (ozone, water vapor, carbon dioxide, etc.)
4. Reflection: reflected back to space by clouds or Earth’s surface (albedo –> reflectivity of surface)

Question 2

Explain the pathways of energy through the ecosystem – conversions, transfers, and transformations

Answer 2

• Conversion = changing from one thing to another
• Transfers = movement from one place to another without change in state, form, or checmical composition
• Transformations = movement with change in form, state, or chemical composition

Question 3

Explain the link between net primary and net secondary productivity of a system and maximum sustainable yield

Answer 3

MSY = the amount of biomass that can be extracted without reducing natural capital of the ecosystem
NPP = baseline for the energy entering an ecosystem

• higher NPP = more energy available for primary consumers –> affects energy available for secondary consumers (NSP)
• the higher the NSP, the more biomass is available for harvesting, which directly influences the calculation of MSY

Question 4

Stores for the carbon and nitrogen cycle

Answer 4

CARBON
- atmosphere
- oceans
- soil
- plants and animals

NITROGEN
- atmosphere
- soil
- oceans (water surfaces)
- plants and animals
- wet soil
- decomposers

Question 5

Discuss the impacts of human activity on energy flows and the carbon and nitrogen cycles

Answer 5

Carbon Cycle:
- deforestation and fossil fuel combustion increase CO2 levels in atmosphere –> high temps

Nitrogen Cycle:
- fertilizer use adds excessive nitrogen to soil –> leads to nitrogen run-off into water –> depletes O2 levels and harms aquatic life

Question 6

Explain nitrogen fixation, high energy fixation, nitrification, assimilation, and denitrification

Answer 6

• NITROGEN FIXATION = nitrogen goes from atmosphere to soil and water surfaces through precipitation, once in the soil and water the nitrogen turns into ammonia
• HIGH ENERGY FIXATION = when lightning strikes it converts atmospheric nitrogen to ammonia and nitrates
• NITRIFICATION = ammonia in plants is converted into nitrite by bacteria
• ASSIMILATION = when nitrogen compounds are taken up by the soil and broken down by decomposers, resulting in the production of ammonia
• DENITRIFICATION = nitrate is converted back to gaseous nitrogen and the nitrogen goes back to the atmosphere, usually happens in wet soils