HS-LS1-7: Cellular Respiration and Energy Release
Also called NGSS HS-LS1-7 · Topic: Matter and Energy in Organisms and Ecosystems · Life Science
The Official Wording
Use a model to illustrate that cellular respiration is a chemical process whereby the bonds of food molecules and oxygen molecules are broken and the bonds in new compounds are formed, resulting in a net transfer of energy.
Clarification statement: Emphasis is on the conceptual understanding of the inputs and outputs of the process of cellular respiration.
Assessment boundary: Assessment should not include identification of the steps or specific processes involved in cellular respiration.
NGSS Lead States, 2013 · Read it on nextgenscience.org · checked October 15, 2026
What HS-LS1-7 Means in Plain English
Students use a model to show that cellular respiration rearranges atoms. Bonds in glucose and oxygen break, new bonds form in carbon dioxide and water, and forming them releases more energy than breaking the old ones took, so the cell gains usable energy and heat.
The focus is inputs, outputs and the energy balance, not glycolysis, the Krebs cycle or other named steps. It pairs with photosynthesis in HS-LS1-5 and leads to HS-LS2-3, where organisms respire with and without oxygen in different settings.
HS-LS1-7 I Can Statements
- I can write the inputs and outputs of cellular respiration.
- I can explain why breaking and forming bonds releases energy overall.
- I can use evidence from living seeds to show respiration is happening.
HS-LS1-7 Worked Example
A thermos experiment that shows sprouting seeds giving off heat and carbon dioxide as they respire.
Do germinating seeds release energy, and how can we detect it?
Set It Up: Two small thermos flasks, peas soaked for two days until they sprout, boiled peas as a control, two thermometers and cotton wool to plug the tops.
- Fill one thermos with germinating peas and the other with boiled peas.Same amount, same starting temperature
- Plug each with cotton wool around a thermometer.Both start at 21 °C
- Read both thermometers once a day for three days.Germinating: 24, 27, 29 °C
- Check the boiled peas each day too.Boiled: stays near 21 °C
- Draw air from each flask with a syringe and bubble it through limewater.Only the live peas' air turns it milky
The germinating peas warmed by about 8 °C and gave off carbon dioxide, while the boiled peas stayed the same.
Why it works: Living cells break down stored starch and sugar with oxygen into carbon dioxide and water, and some of the energy released escapes as heat.
Common Mistakes with HS-LS1-7
Thinking only animals respire
“Plants photosynthesize instead of respiring”
Try this: Nearly every living cell, plant or animal, runs cellular respiration all the time. Plants do both processes, and seeds respire before they have leaves.
Confusing respiration with breathing
“Respiration means taking air into the lungs”
Try this: Breathing moves air in and out of lungs. Cellular respiration is the chemical reaction inside cells that uses the oxygen breathing delivers.
Saying breaking bonds releases energy
“Breaking the bonds in glucose releases energy”
Try this: Breaking any bond takes energy. The net release comes from forming the stronger bonds in carbon dioxide and water.
Where HS-LS1-7 Fits
Practice HS-LS1-7
Quick Check
- What are the inputs and outputs of cellular respiration?
- Why did the boiled peas stay at the same temperature?
- Does C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O conserve atoms?