4.2 Energy Flow Flashcards
Ecosystem
A combination of the abiotic and biotic factors in a particular area
What do most ecosystems rely on?
They rely on the supply of energy from sunlight however energy must be converted into usable forms
Besides light, how else do some ecosystems gain energy?
Through chemicals in the surrounding environment in a process known as chemosynthesis
How do producers capture light?
Through pigments called chlorophyll in reactions like photosynthesis
Briefly outline photosynthesis
- Light breaks water into protons and electrons which transform CO2 and water into glucose and other carbon compounds
- Light energy is thus converted to chemical energy
Saprotrophs
Organisms that feed on non-living/decaying organic matter
Detritivores
They feed on organic waste of decomposed plants and animals
How is energy generated in producers from carbon compounds?
In the form of ATP
Examples of how energy can be used in cellular activities
- Nucleic acid and protein synthesis
- Ion exchange across membranes
- Cell division for reproduction, growth and repair
- Intra-cellular movement of cell components
Why is heat lost when generating energy?
Organisms cannot covert heat to other forms of energy so they are released into immediate surroundings
What happens to carbon compounds that are not immediately used up?
They end up as structural components which when consumed, transfer energy
What are the different types of energy that can be created + examples
- Kinetic: Muscular contractions
- Electrical: Nerve impulses
- Light: Bioluminescence
- Chemical: Anabolism
- Sound: Communication
Food chain
Model that shows how nutrients and energy are passed from producer to subsequent consumers. Shows direction of energy flow as well
Why are producers and autotrophs the first organisms in the food chain?
They do not feed on anything and produce their own nutrition through solar or chemical energy
Trophic level + example
Position of organisms in the food chain eg. producers are first trophic level and primary consumers are second
Which trophic level are decomposers?
They are largely present at every level since they decompose any living matter
Food webs
Interconnections that occur amongst food chains. Each organism may have or be several sources of nutrition for several other organisms
Why is energy transfer never 100%?
- Food may not be entirely consumed (eg. bones)
- Some material is indigestible so they leave body through egestion
- Some energy is contained in waste material which becomes available to saprotrophs and decomposers
What is the estimated energy transfer at each trophic level?
10-20%
How does energy transfer explain predator’s diets?
Top predators receive less energy as they are at higher levels so they have to consume higher number of organisms to meet energy requirements
Why are there fewer organisms at higher trophic levels?
There is a decrease in biomass as we move up and due to their diets, the food pyramid can only support a certain amount of organisms
Biomass
Mass of all dried organic material which can be used as fuel in an ecosystem (dry weight per unit area)
Energy pyramid
Model used to represent energy flow in a community
How should trophic levels be drawn in energy pyramids?
They should be drawn to scale with size of bar representing energy available
Units for energy pyramids
Kilojoules per square meter or megajoules
Numbers pyramid
A model that depicts the number of individuals in each trophic level
Why do some number pyramids have very thin bases?
An organism like a single tree may be able to support thousands of consumers due to its size
Biomass pyramids
Another way to quantify and present ecosystem data. Represents amount of biomass at each level
Why are biomass pyramids usually larger at the base?
They may have multiple producers as compared to consumers like grass
Is energy and nutrients recyclable?
Energy is not recyclable and is instead in constant supply by the sun. Nutrients are finite and recyclable
How are nutrients lost from the ecosystem?
Leaching, harvesting, sedimentation, erosion, burning etc.
Explain flow of energy in an ecosystem
- Enters from sunlight
- Autotrophs capture sunlight
- Energy flows through trophic levels (approx. 10% available at each level)
- Energy is lost through assimilation, egestion, excretion or just by not being consumed
- Energy passes to decomposers, detritivores and saprotrophs as dead matter
- Heat energy is also lost to environment or through cell respiration
Explain the flow of nutrients in ecosystems
- Nutrients are recycled within system
- Nutrients enter from rock weathering, decomposition of dead organisms
- Nutrients move through ecosystem by digestion of other organisms
- Nutrients can be absorbed by producers or plants
- Nutrients are then lost by leaching or sedimentation
