What carbon source do plants use to synthesise organic compounds, and where do they obtain it?
Carbon dioxide from the atmosphere or water.
AQA A-Level Biology - (7402) · 3.5.3
Revise AQA A-Level Biology - (7402) specification point 3.5.3, Energy and ecosystems (A-level only), with free active-recall flashcards. Flip through the set or review every question and answer below.
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What carbon source do plants use to synthesise organic compounds, and where do they obtain it?
Carbon dioxide from the atmosphere or water.
How are the sugars produced by plants used?
Most are used as respiratory substrates; the remainder can make other biological molecules that contribute to biomass.
How can plant biomass be expressed per unit area?
As the mass of carbon or the dry mass of tissue per unit area.
Why is dry mass used to measure plant biomass?
It excludes water, so the measurement of organic material does not vary with water content.
How can calorimetry estimate the chemical energy stored in plant dry biomass?
By measuring the heat released when a dried sample is burned.
What is gross primary production (GPP)?
The total chemical energy incorporated into plant biomass in a given area or volume, before respiratory losses are subtracted.
How is net primary production (NPP) calculated from gross primary production (GPP)?
where is energy lost to the environment through respiration.
What is net primary production available for?
Plant growth and reproduction, and use by other trophic levels.
What is primary productivity?
The rate of primary production, expressed per unit time and per unit area or volume.
What is consumer net production?
The chemical energy from ingested food remaining after losses in faeces and urine and respiratory losses.
What equation calculates consumer net production, and what do its symbols represent?
What is consumer net production available for?
The consumer’s production of new biomass.
What is secondary productivity?
The rate of secondary production, expressed per unit time and area or volume.
How can simplifying a food web increase production for humans?
It reduces transfers to non-human food chains, diverting less production away from the human food chain.
How can reducing respiratory losses in a human food chain increase energy available for production?
Less energy is lost to the environment through respiration, leaving a greater proportion for production.