Energy and ecosytems 3.5.3 (Energy transfers in and between organisms 3.5) Flashcards
What is an ecosystem?
A biological community of interacting organisms and their physical environment.
What is the ultimate source of energy for most ecosystems?
The sun.
Define primary producers in an ecosystem.
Organisms that produce their own food through photosynthesis, such as plants.
What is the role of decomposers in an ecosystem?
Decomposers break down dead organic matter into simpler substances, recycling nutrients back into the ecosystem.
What is a trophic level in an ecosystem?
A position in the food chain, such as primary producers, primary consumers, secondary consumers, etc.
What is a food chain?
A linear sequence of organisms through which nutrients and energy pass in an ecosystem.
What is a food web?
A complex network of interconnected food chains in an ecosystem.
What is the 10% rule in energy transfer in ecosystems?
Only about 10% of the energy from one trophic level is transferred to the next trophic level.
What is the difference between a food chain and a food web?
A food chain shows a linear sequence of organisms, while a food web shows a complex network of interconnected food chains.
What is the difference between a producer and a consumer in an ecosystem?
Producers create their own food through photosynthesis, while consumers obtain energy by consuming other organisms.
What is a biotic factor in an ecosystem?
Living components of an ecosystem, such as plants, animals, and bacteria.
What is an abiotic factor in an ecosystem?
Non-living components of an ecosystem, such as temperature, water, and sunlight.
What is the importance of biodiversity in an ecosystem?
Biodiversity ensures the stability and resilience of ecosystems, as well as providing valuable ecosystem services.
What is the difference between a habitat and a niche in an ecosystem?
A habitat is the physical environment where an organism lives, while a niche is the role and position of an organism within its habitat.
What is the role of a predator in an ecosystem?
Predators help control the population of prey species, maintaining the balance of the ecosystem.
What is Gross Primary Production (GPP)
The chemical energy store in plant biomass , in a given area or volume
What is the Net primary production (NPP)
the chemical energy store in plant biomass after respiratory losses to the environment have been taken into account
What is another word for a decomposer
Saprobiant
Between each tropic level how is energy lost
•Majority of energy is lost due to respiration (heat energy) and excretion
• The remaining every is used to form the biomass
What is biomass
The total mass of living material in a specific area at a time
How can the amount of biomass remaining in an organism be measured
It can be measured in terms of mass of carbon or dry mass of tissue per given area
How can an ecosystem be more productive
- depends on the abiotic and biotic factors
- Higher abiotic and biotic factors will maximise rates of photosynthesis
- More carbohydrates being produced in plants
- So more carbon produced into food webs at the start
How can net primary production be calculated
NPP = GPP - R
R = respiration
GPP = gross primary production
What is NPP in the NPP calculation
The energy left over that is available to the plant to create new biomass and therefore available to the next tropic level in a food web
What is the equation for net production of consumers
N = I - ( F+R)
I = chemical energy store in ingested food
F = the chemical energy lost to the environment in faeces and urine
R = Respiratory losses
what could the units for rates of productivity include
KJ/ m^2 / day
or KJ / ha ^-1 / year ^-1
why are the units recorded per unit area
Per unit area takes into account that different environments vary in size.
- Standardising results to enable comparisons between environments
Why are units in KJ
the unit for energy which also includes per unit area and per year
Why are units per year
Per year takes into account seasonal variations on biomass
- More representative and enables comparison between environments
How might energy be lost in the transfer from the sun to the producers
- Reflection / absorption of the sun by the atmosphere
- Chlorophyll only absorbs scientific wavelengths
- Not all light will fall on chlorophyll
- limiting factors
Describe how biomass is formed in plants
• During photosynthesis , plants make organic compounds from atmospheric CO2
• Most sugars synthesised are used by the plant as respiratory substrates
• Rest used to make other groups of biological molecules
how can biomass be measured
Mass or carbon or dry mass of tissue per given area
Describe how dry mass of tissue can be measured
1) sample dried in an oven e.g. at 100 degrees
2) sample weighed and reheated at regular intervals
3) until mass remains constant
Explain why dry mass is more representative than fresh ( wet ) mass
Water volume in wet samples will very but will not affect dry mass
Describe how the chemical energy stored in dry biomass can be estimated
Using calorimetry :
1) known mass of dry biomass is fully combusted
2) heat energy released heats a known volume of water
3) increase in temperature of water is used to calculate chemical energy of biomass
explain how features of a calorimeter enable valid measurement of heat energy released
• stirrer => evenly distributes heat energy
• Air / insulation => reduces heat loss and gain to and from surroundings
• water => has a high specific heat capacity
Explain the importance of NPP in ecosystems
• NPP is available for plant growth and reproduction
• NPP is also available to other trophic levels in the ecosystem, such as herbivores and decomposers
What is primary or secondary productivity
The rate of primary or secondary production
State the formula for efficiency of energy transfer
Energy or biomass available after transfer / Energy or biomass available before transfer x100
Explain why energy transfer between trophic levels is inefficient
• Heat energy is lost via respiration
• Energy lost via parts of an organism that aren’t eaten
• Energy lost via food not digested => lost as faeces
• Energy lost via excretion
Explain how crop farming practices increase energy transfer efficiency
- Simplifying food webs to reduce energy / biomass losses to non human food chains e.g.
• Herbicides kill weeds => less competition
• Pesticides kill insects => reduce loss of biomass from crops
• Fungicides reduce fungal infections => more energy to create biomass - Fertilisers to prevent poor growth due to lack of nutrients
Explain how livestock farming practices increase energy transfer efficiency
• Reducing respiratory losses within a human food chain :
- Restrict movement and keep warm => less energy lost as heat from respiration
- Slaughter animal while still growing / young , when most of their energy is used for growth
- Treated with antibiotics => prevent loss of energy due to pathogens
- Selective breeding to produce breeds with higher growth rates
