2.2 Energy and Biomass in Ecosystems
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How are energy and matter sustained in ecosystems?
Energy flows from the sun to producers, then through trophic levels. Matter is recycled within ecosystems through biogeochemical cycles.
What does the first law of thermodynamics state about energy flow?
Energy can be transformed but not created or destroyed.
What is the word equation for photosynthesis?
Carbon dioxide + water -> glucose + oxygen
What is photosynthesis?
Conversion of light energy to chemical energy in the form of glucose, stored as biomass by autotrophs.
What feeding relationships can be modeled using food chains, food webs, and ecological pyramids?
Producers, consumers, and decomposers.
What is a trophic level?
The position an organism occupies in a food chain.
What are producers (autotrophs)?
Plants or algae that produce their own food using photosynthesis.
What is a consumer (heterotroph)?
An organism that obtains nutrition by eating other organisms.
What does a primary consumer (herbivore) eat?
Eats producers (e.g., sea urchin, copepod).
What does a secondary consumer (carnivore) eat?
Eats primary consumers (e.g., wolf eel, herring).
What is a decomposer?
An organism that obtains energy by breaking down dead organic matter.
What does a food chain show?
Shows one path of energy and nutrients through an ecosystem.
What does a food web show?
Shows all possible food chains in an ecosystem, illustrating complex trophic relationships.
What is respiration?
Conversion of organic matter into carbon dioxide and water, releasing energy.
What is the word equation for aerobic respiration?
Glucose + oxygen -> carbon dioxide + water.
What does the second law of thermodynamics state about energy transformations?
Energy transformations are inefficient, increasing the disorder (entropy) in a system.
What happens to energy and organic matter in a food chain?
Losses of energy and organic matter occur as food is transferred along a food chain.
Why is the number of trophic levels in ecosystems limited?
Limited due to energy losses (10% rule).
What are ecological pyramids used for?
Represent relative numbers, biomass, or energy of trophic levels.
What do ecological pyramids include?
Numbers, biomass, and productivity.
How is biomass of a trophic level measured?
Measured by collecting and drying samples.
What is bioaccumulation?
Build-up of non-biodegradable pollutants within an organism or trophic level.
What is biomagnification?
Increase in concentration of non-biodegradable pollutants along a food chain.
How do microplastics affect pollutant transmission?
Pollutants are absorbed within microplastics, increasing their transmission in the food chain.
What human activities impact flows of energy and transfers of matter in ecosystems?
Burning fossil fuels, deforestation, urbanization, and agriculture.
What is Gross Productivity (GP)?
Total gain in biomass by an organism.
What is Net Productivity (NP)?
Amount remaining after losses due to cellular respiration (NP = GP - R).
What is primary productivity?
Rate of production of biomass by producers using an external energy source.
What is net primary productivity (NPP)?
Quantity of carbon compounds sustainably available to primary consumers (NPP = GPP - respiration).
What are Respiratory Losses (R)?
Organisms use some of the energy they capture to keep themselves growing and alive (metabolism).
What do Autotrophs do?
Synthesize carbon compounds from inorganic sources.
What do Heterotrophs do?
Obtain carbon compounds from other organisms.
What do Photoautotrophs do?
Use light as an energy source for photosynthesis.
What do Chemoautotrophs do?
Use exothermic inorganic chemical reactions as an energy source for chemosynthesis.
What is secondary productivity?
Biomass gained by consumers through feeding and absorption.
How do you calculate Gross Secondary Productivity?
Food eaten (J) – fecal losses
What is Secondary Productivity?
The rate at which CONSUMERS in an ecosystem store energy.
What affects productivity?
Solar radiation, temperature, CO2, H2O, nutrients, herbivory.
What are Maximum Sustainable Yields (MSYs)?
Net primary or net secondary productivity of a system.
What is ecological efficiency?
Percentage of energy received by one trophic level that is passed to the next level.
How does the second law of thermodynamics show how the entropy of a system increases as biomass passes through ecosystems?
Cellular respiration releases energy as heat, undigested materials are excreted, and decomposers break down dead matter.