5.3 Energy and ecosystem Flashcards
In a food chain/ ecosystem who are the producers, and why
Plants since they’re able to produce their own carbohydrates using CO2
What is a trophic level
Each stage in a food chain
How can energy be lost from trophic level to trophic level
- Respiration
- Excretion
What is the energy remaining for the next trophic level called
Biomass
How can biomass be measured
- Measuring mass of carbon per given area
- Measure the dry mass of tissue per given area
What does GPP stand for
Gross Primary Production
What is GPP / what does it measure
The chemical energy store in plant biomass, in a given area. It’s the total energy resulting from photosynthesis
What does NPP stand for
Net Primary Production
What is NPP/ what does it measure
The chemical energy store in plant biomass taking into account the energy that will be lost due to respiration
What is the equation linking NPP, GPP, and R
NPP=GPP-R
Is the NPP or the GPP the energy left over that is available to the plant to create new biomass and therefore available to the next trophic level in a food web
The NPP because it takes into account of the energy lost by respiration
What is the equation for next production of consumers
N=I-(F+R)
In the equation N=I-(F+R), what do the letter stand for
- I energy ingested in food
- F chemical energy lost to the environment in faces and urine
- R energy lost in respiration
- N Net production of consumers
To figure out the unit of rates of productivity, what 3 things must be included
- The units for energy
- Per unit area
- Per year
When adding units to rates of productivity, why must we record data over an entire year
To take into account the impact seasons will have on rain, light and heat- so provides an annual average to allow fair comparisons between environments
Averagely, how much energy is laid down as biomass between each trophic level
About 10%
What type of food is indigestible
Cellulose
Why do primary consumers contribute a larger proportion of their energy to dead organic matter rather than to respiration
Since they tend to eat plants which contain cellulose which is indigestible so ends up as faeces and lost from the system as dead organic matter for the decomposers
Who passes on more energy ? Mammals or invertebrates
Invertebrates because they aren’t endotherms so use up less glucose so more is available to lay down as biomass for the trophic level
What is the max number of trophic levels in a food chain
Five but tends to only be 4 since there is not enough energy to support another trophic level
What is photosynthetic energy
The measure of how well a plant can capture light energy and convert it into chemical energy
What are the 5 ways why light energy isn’t always used in photosynthesis
- Reflected (waxy cuticle)
- Green light isn’t absorbed
- Transmitted (doesn’t hit the chlorophyll molecule)
- Some light energy absorbed by water
- Low carbon dioxide concentrations for photosynthesis so plant does not absorb unnecessary light
Give 3 reasons for the low efficiency of energy transfer from secondary consumers to tertiary consumers in an ecosystem (3 marks)
- Heat (loss) from respiration;
- (Food) not digested
OR
Not all eaten; - Excretion;
Suggest 2 reasons for conserving rainforests
- Conserve/protect
species/plants/animals/organisms
OR
For (bio)diversity; - Conserve/protect habitats/niches
OR
Provides/many habitats/niches; - Reduces climate change;
- Source of medicines/drugs/wood;
- Reduces erosion/eutrophication;
- (For) tourism;
Farming cattle for humans to eat is less efficient than farming crops because of
energy transfer.
Explain why. (2 marks)
- Energy lost between/at trophic/feeding levels;
- Energy lost via respiration/excretion/faeces;
