Lecture 3 - Energy in the Ecosystem Flashcards
What are producers?
Photosynthetic organisms that manufacture organic substrates using light energy, water and carbon dioxide.
What are examples of a producer?
Green plants and phytoplankton
What are autotrophs?
Organisms that synthesise their own organic molecules from inorganic substrates.
What are consumers?
Organisms that obtain their energy by consuming other organisms
What are primary consumers?
Animals that directly eat producers
What are secondary consumers?
Animals that eat primary consumers
What are tertiary consumers
Animals that eat secondary consumers
What are decomposers?
- Feed on the remaints of producers and consumers to obtain energy
- They break down complex substrates to simple molecules releasing minerals and elements into forms absorbable by plants
What are examples of decomposers?
Fungi and bacteria
2. Detritvores such as earth worms can also help
What is a food CHAINS?
- The feeding relationship from producers through to tertiary consumers.
- Each stage in a food chain is a tropic level where the arrows represent the flow of energy
What are tropic levels
- Producer
- Primary Consumer
- Secondary Consumer
- Teritary Consumer
- Quanternary consumer
What are food WEBS
Series of interlinking food webs showing the flow of energy through a habitat
2. Illustrate that an organism are eaten by more than one type of consumer
Why is most of the suns energy not converted into organic matter?
- 90% of sun energy reflected by dust and clouds into space
- Not all wavelengths of light are used by photosynthesis and leaf also reflect light
- Light might not fall on chlorophyll molecules
- Other limiting factors
How do you calculate energy converted
NPP= GPP-R
- Plant use energy from sunlight to synthesise plant tissue or bio mass (GPP)
- Respiration (R)
- Energy left (NPP)
What is GPP
Total quantity of light energy that plants in a community convert to organic matter in a given area and time
What is NPP
rate at which energy is stored by plants
Why is there low % energy transfer for consumers
- Not all parts of an organism is eaten
- Some parts are consumed but not digested
- Some energy lost in excretory materials e.g. urine
- Energy lost as heat from respiration
What is the % of energy lost between the tropic levels
- Sun 1.3% –>
- Primary Producers 5-10% –>
- Primary Consumers 5-20%
- Secondary Consumers 15-20%
Why are food chains limited to 4 or 5 organisms
- Relative inefficiency of energy transfer
- Usually have 4 to 5 trophic levels, not enough energy to support large breeding populations and levels higher than this
3 Biomass of organisms is less at higher levels - Total amount of energy stored at each level is less
How to calculate efficiency of energy transfer?
energy transfer =
(energy available after transfer/ (divide)
energy available before transfer)
x 100
What are ecological pyramids?
- Provides quantitative data such as numbers of biomass and energy stored at each tropic level
Why is there sometimes fewer organisms in the lower tropic energy levels?
- Size: One oak tree is treated the same as a parasite
2. The number of individuals is so great that they cannot be accurately drawn to scale
What is biomass
total mass of plants and or animals
What is Fresh biomass
Includes water content- which is variable
