EN: Energy Transfer in Ecosystems Flashcards
Producers
Photosynthetic organisms that manufacture organic substances using light energy, water, carbon dioxide and minerals.
Consumers
Organisms that obtain their energy by feeding on other organisms rather than using the energy of sunlight directly.
Primary consumer
Those that directly eat producers.
Secondary consumer
Those that eat primary consumers.
Tertiary consumers
Those that eat secondary consumers.
Saprobionts
Group of organisms that break down that break down the complex materials in dead organisms into simple ones.
Food chain
A feeding relationship in which producers are eaten by primary consumers, which are eaten by secondary consumers, which are then eaten by tertiary consumers.
Trophic level
A stage in the food chain.
Food webs
Many food chains linked together.
Biomass
Total mass of living material in a specific area at a given time.
Why is fresh mass unreliable?
Contains varying amounts of water which will affect mass.
Photosynthetic organisms that manufacture organic substances using light energy, water, carbon dioxide and minerals.
Producers
Organisms that obtain their energy by feeding on other organisms rather than using the energy of sunlight directly.
Consumers
Those that directly eat producers.
Primary consumer
Those that eat primary consumers.
Secondary consumer
Those that eat secondary consumers.
Tertiary consumers
Group of organisms that break down that break down the complex materials in dead organisms into simple ones.
Saprobionts
A feeding relationship in which producers are eaten by primary consumers, which are eaten by secondary consumers, which are then eaten by tertiary consumers.
Food chain
A stage in the food chain.
Trophic level
Many food chains linked together.
Food webs
Total mass of living material in a specific area at a given time.
Biomass
Ecosystem
All the organisms in an area, including biotic and abiotic factors.
Briefly, what happens in photosynthesis?
Plants use energy from sunlight and carbon dioxide to make glucose and other sugars.
What can biomass also be thought of?
The chemical energy stored in the plant.
What are the sugars produced in photosynthesis used for?
- Some used for respiration - to release energy for growth.
- Rest is used to make biological molecules - like cellulose- which makes up a plant’s biomass.
What are the terms biomass can be measured in?
- Mass of carbon that an organism contains.
- Dry mass of its tissue per unit area.
Dry mass
Mass of an organism with the water removed.
All the organisms in an area, including biotic and abiotic factors.
Ecosystem
Mass of an organism with the water removed.
Dry mass
How would you obtain a dry mass sample?
- Sample of organism is dried - often in an oven set to a low temperature.
- Sample is weighed at regular intervals (eg every day).
- When the mass becomes constant all the water has been removed.
Results can be scaled up to give dry mass of the total populatio or area being investigated.
What might a typical unit for dry mass be?
kg m-2
Compared to dry mass, what is the mass of carbon generally taken to be?
Mass of carbon is generally taken to be 50% of dry mass.
How can the chemical energy store in dry mass be estimated?
Using calorimetry
Describe the steps in bomb calorimetry:
- Sample of dry mass is weighed.
- Burnt in pure oxygen within a sealed chamber called a bomb.
- Bomb is surrounded by water bath.
- Temperature rise is measured - as we know how much heat is required to raise the temperature of 1g of water by 1oC.
What are the units for the energy released by burnt biomass?
kJ kg-1
Gross primary production (GPP)
Total amount of chemical energy converted from light energy by plants in a given area.
What is the most common cause of gross primary production loss?
Approximately 50%
Respiratory loss - energy lost to the environment as heat when plants respire.
Net primary production (NPP)
The chemical energy store left when losses to respiration have been taken into account.
Energy available for the plant for growth and reproduction.
What is the equation for NPP for producers?
NPP = GPP - R
Total amount of chemical energy converted from light energy by plants in a given area.
Gross primary production (GPP)
The chemical energy store left when losses to respiration have been taken into account.
Energy available for the plant for growth and reproduction.
Net primary production (NPP)
What are typical units for primary production?
kJ m-2 yr-1
When primary production is expressed as a rate, what is it called?
Primary productivity.
How might consumers lose energy?
- Not all parts of the food are eaten - bones, plant roots.
- Of ingested materials:
- Some are indigestible - egested as faeces.
- Energy is lost to environment through respiration or excretion of urine.
How can the net production of consumers be calculated?
N = I - (F+R)
- I = chemical energy in ingested food.*
- F = chemical energy lost in faeces and urine*
- R = energy lost through respiration*
Percentage efficiency equation:
(energy available after transfer / energy available before transfer) x 100
