Energy Flow
What is the original source of almost all energy in ecosystems?
The Sun
Which organisms break down dead plants and animals to recycle matter?
Decomposers
What is the first organism in every food chain?
Producer
What is the main pigment in plants that captures light energy?
Chlorophyll
What three elements are found in sugar (glucose)?
Carbon, hydrogen, and oxygen.
Only about ___% of energy is passed from one trophic level to the next.
10%
What element do plants take in during photosynthesis?
Carbon dioxide (CO₂)
Give an example of a primary consumer.
Grasshopper, rabbit, cow, etc.
During photosynthesis, what molecule provides oxygen gas that plants release?
Water (H₂O)
Which gas containing carbon do animals release during cellular respiration?
Carbon dioxide (CO₂)
Why is energy lost at each trophic level?
Used for life processes and lost as heat.
This is the process that uses sunlight to make glucose.
photosynthesis
These organisms form the base of most food webs.
producers
Where is energy stored in a carbohydrate molecule like glucose?
In the chemical bonds between carbon, hydrogen, and oxygen atoms.
How is glucose built from smaller molecules in photosynthesis?
Carbon dioxide and hydrogen from water are combined using energy from sunlight to form glucose.
Why are top predators (like hawks or lions) fewer in number than herbivores?
There is less energy available at higher trophic levels.
This is the role of decomposers in the carbon cycle.
breaking down organic matter and releasing carbon dioxide
This pyramid shows how energy decreases at each trophic level.
energy pyramid
Write the basic equation for photosynthesis in words.
Carbon dioxide + water + sunlight → glucose + oxygen.
How does burning fossil fuels affect the carbon cycle?
It releases stored carbon as CO₂ into the atmosphere, increasing greenhouse gases.
An ecosystem starts with 100,000 J of energy in producers. How much energy would be available to tertiary consumers?
About 100 J
A dead tree decomposes. Describe how the carbon in the tree could eventually end up in another living organism.
Decomposers release CO₂ → plants take it in → animals eat the plants.
This is where the other 90% of energy goes in an energy pyramid.
digestion, movement, and cellular respiration
Explain how photosynthesis and cellular respiration are related in the cycling of matter and energy.
The products of photosynthesis (glucose and oxygen) are the reactants of cellular respiration; the products of respiration (CO₂ and water) are the reactants of photosynthesis. This links energy flow and matter cycling.
How does the transfer of C, H, and O in glucose connect to both energy flow and matter cycling in ecosystems?
Energy stored in glucose bonds is released as ATP, while the C, H, and O atoms are recycled through photosynthesis, respiration, and decomposition.