Photosynthesis and Respiration Review

Photosynthesis and Respiration Review

Middle School

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Learning Objectives

• Identify the reactants and products of photosynthesis and cellular respiration.

• Explain how these processes are connected for the flow of energy and matter.

• Trace the path of energy from the sun, to glucose, to ATP.

• Relate photosynthesis and cellular respiration to their roles in the carbon cycle.

Key Vocabulary

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Photosynthesis

The process plants use to convert light, water, and CO₂ into their own food.

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Cellular Respiration

The process of breaking down glucose with oxygen to produce usable energy, called ATP, for cells.

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Chloroplast

The organelle inside plant cells where the entire process of photosynthesis takes place.

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Mitochondria

The organelle where cellular respiration occurs, breaking down glucose to release energy for the cell.

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ATP (Energy Molecule)

An energy-rich molecule that powers all chemical activities and essential functions within a living cell.

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Glucose (Simple Sugar)

A simple sugar with the formula C₆H₁₂O₆ that is a major energy source for organisms.

The Process of Photosynthesis

• Plants use sunlight, water, and carbon dioxide to create their food.

• Light energy is converted into chemical energy inside the chloroplasts.

• This process produces glucose (C₆H₁₂O₆) for energy and releases oxygen.

Multiple Choice

A student is conducting an experiment to demonstrate that carbon dioxide is essential for photosynthesis. The student places a healthy potted plant in a bell jar setup for several hours with access to sunlight. Which chemical should the student include inside the bell jar to remove carbon dioxide and effectively test the hypothesis?

• Sodium chloride solution

• Dilute sulfuric acid

• Potassium hydroxide pellets

• Calcium chloride granules

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The Process of Cellular Respiration

• Cells get energy from food through a process called cellular respiration.

• It happens in the mitochondria and works best when oxygen is present.

• Glucose (C₆H₁₂O₆) and oxygen (6O₂) are the reactants.

• The products are carbon dioxide (6CO₂), water (6H₂O), and energy (ATP).

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Multiple Choice

What are the primary products of cellular respiration that occur in the mitochondria?

• Glucose, oxygen, and energy.

• Carbon dioxide, water, and ATP.

• Water, light energy, and oxygen.

• Carbon dioxide, glucose, and water.

The Connection: A Balanced Cycle

• The products of one process are the reactants of the other.

• Photosynthesis uses CO₂, water, and light to make food and oxygen.

• Cellular respiration uses food and oxygen to release energy, CO₂, and water.

Multiple Choice

What is the relationship between the substances involved in photosynthesis and cellular respiration?

• The reactants of photosynthesis are also the reactants of cellular respiration.

• The products of both processes are identical.

• The products of photosynthesis are the reactants for cellular respiration.

• There is no relationship between the two processes.

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Energy and Matter in Ecosystems

Energy Flow

• ​Producers, like plants, make their own food and capture energy from the sun through photosynthesis.

• ​​Consumers get energy by eating other organisms, passing that stored energy through the food web.

• ​This energy flows in one direction and is used by cells to perform life functions like respiration.

Cycling of Matter

• ​Food provides the matter (atoms) organisms need to build and repair their bodies, like skin and bone.

• ​​Matter is not created or destroyed; the atoms from food are just rearranged into new molecules.

• ​Elements like carbon and oxygen are constantly recycled between living things and the nonliving environment.

Multiple Choice

How do producers and consumers fit into the flow of energy and matter?

• Producers and consumers both create their own food using light energy.

• Producers consume other organisms, and consumers use light energy to grow.

• Producers release energy as ATP, which is then consumed by other organisms.

• Producers capture light energy to make food, and consumers release the energy from that food through respiration.

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Common Misconceptions

Misconception	Correction
Plants only perform photosynthesis.	Plants perform both photosynthesis and cellular respiration.
Cellular respiration is the same as breathing.	Breathing is gas exchange; cellular respiration is a chemical process.
Plants create energy from sunlight.	Plants convert light energy into stored chemical energy.
The light reactions and Calvin cycle happen at different times.	Both happen when light is available.

Multiple Choice

Why are photosynthesis and cellular respiration essential for the carbon cycle?

• Photosynthesis releases CO₂, and respiration removes it from the atmosphere.

• Both processes remove CO₂ from the atmosphere, decreasing carbon levels.

• Both processes release CO₂ into the atmosphere, increasing carbon levels.

• Photosynthesis removes CO₂ from the atmosphere, and respiration releases it back.

Multiple Choice

What is the primary difference in how producers and consumers obtain the matter they need for growth?

• Producers convert inorganic matter (CO₂, H₂O) into organic food, while consumers eat other organisms.

• Producers absorb matter from the air, while consumers absorb it from water.

• Producers eat other organisms for matter, while consumers convert sunlight into matter.

• Producers and consumers both obtain matter by breaking down rocks and soil.

Multiple Choice

A plant is placed in a sealed container with plenty of light, water, and soil. Predict what would happen to the levels of oxygen and carbon dioxide inside the container over time.

• Carbon dioxide will increase and oxygen will decrease, as respiration outpaces photosynthesis.

• Both gases will remain at a constant, stable level indefinitely.

• Oxygen will increase and carbon dioxide will decrease, as photosynthesis outpaces respiration.

• Both gases will be completely used up by the plant.

Multiple Choice

Analyze the consequences for an ecosystem if a disease eliminated most of the decomposers (like bacteria and fungi) that perform cellular respiration. How would this impact producers?

• Producers would not be affected, as they get carbon dioxide directly from the atmosphere.

• Producers would thrive due to having less competition for sunlight and water.

• Producers would suffer from a lack of available carbon dioxide, as it would not be recycled from dead organic matter.

• Producers would switch from photosynthesis to cellular respiration to survive.

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Summary

Poll

On a scale of 1-4, how confident are you about the concepts covered in today's review?

• 1 - Very Unconfident

• 2 - Somewhat Unconfident

• 3 - Somewhat Confident

• 4 - Very Confident