Conservation & Energy
This law states that matter is neither created nor destroyed during any chemical or physical change
Law of Conservation of Mass
Two hydrogen atoms and one oxygen atom form this molecule essential for life.
water
During photosynthesis, producers take in this carbon-containing gas from the air.
Carbon Dioxide
The air is about what percent nitrogen gas? Give the number (no % sign needed).
78
A sealed terrarium is described as this type of system for matter (two words).
Closed system
During photosynthesis and cellular respiration, energy changes form but is not lost. Name this law.
Law of Conservation of Energy
Name the process where liquid water gains energy and becomes water vapor
Evaporation
Name one product released by cellular respiration that returns carbon to the atmosphere.
Carbon Dioxide
Most organisms cannot use free nitrogen gas. Name the process that converts free nitrogen into a usable form for plants
Nitrogen fixation
If trees are cut and burned, how does this affect atmospheric carbon dioxide levels? Give a short explanation.
Carbon dioxide levels increase because burning trees releases stored carbon into the atmosphere.
In a closed system, total mass stays the same. Give one classroom example of a closed system where matter cannot enter or exit.
closed jar/sealed terrarium
What is the process called when water vapor cools and forms tiny liquid droplets in the atmosphere?
Condensation
Explain how consumers obtain carbon and how decomposers return carbon to the environment (two short sentences).
Consumers obtain carbon by eating producers or other consumers. Decomposers break down dead organisms and release carbon back to the soil and air.
Name one biological agent that performs most nitrogen fixation and where it lives (give both)
Bacteria living in root nodules of legume plants
Explain why removing forests reduces the amount of carbon dioxide absorbed from the atmosphere (one or two sentences)
Fewer trees means fewer producers to absorb carbon dioxide through photosynthesis. This causes CO₂ levels in the air to rise.
Write the short explanation of how cellular respiration and photosynthesis demonstrate conservation of matter (mention reactants or products).
Photosynthesis and cellular respiration rearrange matter. The same atoms are used in reactants (CO₂, H₂O, O₂, glucose) and appear again in products, so matter is conserved.
List the three main stages of the water cycle discussed (use one word each).
Evaporation, condensation, precipitation
Describe one human activity that increases carbon dioxide levels in the atmosphere and explain why.
Example: Burning fossil fuels releases carbon dioxide into the atmosphere because carbon stored in fuels combines with oxygen during combustion.
Describe how decomposers contribute to carbon cycling when organisms die. Include the term "cellular respiration
Nitrogen moves from soil into producers, then to consumers through eating. Bacteria eventually return nitrogen to the air or soil, continuing the cycle.
Describe how decomposers contribute to carbon cycling when organisms die. Include the term "cellular respiration
Decomposers break down dead organisms using cellular respiration, releasing carbon dioxide back into the atmosphere.
A sealed terrarium has plants, soil, rocks, water, and air. Over months the materials change form but total mass stays constant. Explain in two sentences how the Law of Conservation of Mass and the Law of Conservation of Energy together describe what happens in the terrarium.
In the terrarium, matter changes form but is not created or destroyed, so total mass stays the same. Energy from sunlight is transformed during photosynthesis and respiration but is never lost.
Describe how evaporation from plants (transpiration) and evaporation from bodies of water both contribute to cloud formation. Include the energy source.
Plants release water vapor through transpiration, and water evaporates from lakes and oceans. Both processes use energy from sunlight and add water vapor to the air, helping form clouds.
Explain how the Law of Conservation of Mass applies to the cycling of carbon and oxygen atoms through photosynthesis and respiration. Use the words "atoms", "compounds", and "recycled" in your answer.
Carbon and oxygen atoms are not destroyed during photosynthesis and respiration. The atoms move through different compounds and are recycled through ecosystems.
Propose one realistic classroom investigation (1–2 sentences) using a small closed container to observe conservation of mass and name the data you would collect.
Biological: nitrogen-fixing bacteria in legume root nodules. Non-biological: lightning fixing nitrogen in the atmosphere.
Propose one realistic classroom investigation (1–2 sentences) using a small closed container to observe conservation of mass and name the data you would collect.
Example: Seal soil and plant material in a closed container and measure mass over time. Data collected could include mass, temperature, and visible changes.