Energy Flow in Organisms

Energy Flow in Organisms

Middle School

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Learning Objectives

• Explain how photosynthesis helps matter cycle and energy flow in organisms.

• Model how chemical reactions rearrange food to form new molecules for growth.

• Trace the path of energy from the sun to food to the creation of ATP.

• Relate photosynthesis and cellular respiration to the global carbon cycle.

Key Vocabulary

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Photosynthesis

Photosynthesis is the process plants use to convert light, water, and carbon dioxide into their food.

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Cellular Respiration

Cellular respiration is the process of breaking down glucose to produce energy for the cell's activities.

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Chemical Reaction

A chemical reaction is a process that rearranges the structure of molecules or atoms into new substances.

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Conservation of Matter

The law of conservation of matter states that atoms are not created or destroyed in a reaction.

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Cycling of Matter

The cycling of matter describes the continuous movement of essential elements through an ecosystem's living and nonliving parts.

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Flow of Energy

The flow of energy is the one-way transfer of energy between different organisms in an ecosystem.

Key Vocabulary

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ATP

Adenosine triphosphate (ATP) is the main energy-carrying molecule used to power all activities in a cell.

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Mitochondrion

This is the specific organelle inside a cell where the process of cellular respiration happens.

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Phototrophs

These are organisms, like plants, that produce their own food by using energy from light.

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Carbon-based molecules

These molecules, like sugars and fats, are essential for life and are built around carbon atoms.

How Organisms Get Energy

• All living things require energy to live and grow.

• Producers make their own food through a process called photosynthesis.

• Consumers get their energy by eating other living organisms.

Multiple Choice

What is the main difference in how producers and consumers obtain energy?

• Producers make their own food, while consumers get energy by eating other organisms.

• Producers get energy by eating other organisms, while consumers make their own food.

• Producers require energy to live and grow, while consumers do not.

• Producers get energy from sunlight, while consumers get energy from water.

Multiple Choice

According to the information, why is it essential for all organisms to obtain energy?

• To be able to live and grow.

• So they can perform photosynthesis.

• Because they need to eat other organisms.

• So they can have a role in the ecosystem.

Multiple Choice

What would be the most likely outcome for consumers if all producers were suddenly eliminated?

• The consumers' primary energy source would be removed, and they would not be able to survive.

• The consumers would be unaffected because they get energy from eating other living things.

• The consumers would adapt and begin making their own food through photosynthesis.

• The consumers would have more room to grow, so their populations would increase.

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Photosynthesis and Cellular Respiration

Photosynthesis

Cellular Respiration

Multiple Choice

What is the primary purpose of photosynthesis?

• To capture light energy and store it in the chemical bonds of glucose.

• To release stored chemical energy for the cell to carry out its functions.

• To break down glucose into carbon dioxide and water.

• To absorb ATP from the environment to power the cell.

Multiple Choice

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

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

• Both processes require an input of light energy to begin.

• Both processes produce glucose and oxygen for the organism.

• The reactants of photosynthesis are the same as the reactants for cellular respiration.

Multiple Choice

If a plant were able to perform photosynthesis but unable to perform cellular respiration, what would be the most likely consequence?

• The plant would produce glucose but would not be able to release its stored energy to power cell functions.

• The plant would be unable to take in carbon dioxide and water from its environment.

• The plant's cells would have too much ATP and stop producing oxygen.

• The plant would immediately stop capturing light energy and wilt.

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The Role of Photosynthesis in Ecosystems

• Photosynthesis is the foundation for energy flow and matter cycling in most ecosystems.

• Sunlight's energy is converted into chemical energy stored in the bonds of glucose.

• It uses simple molecules like carbon dioxide (CO₂) and water (H₂O).

• This moves matter from the non-living environment into the food web.

Multiple Choice

What is the primary role of photosynthesis in an ecosystem?

• It is the foundation for energy flow and matter cycling.

• It is a process that helps animals breathe.

• It is a method for creating water from sunlight.

• It is the process of breaking down dead organisms.

Multiple Choice

How does photosynthesis transfer matter from the non-living world into the food web?

• By converting carbon dioxide and water into food molecules.

• By turning chemical energy back into light energy.

• By taking in food molecules from the soil.

• By releasing energy from the non-living world.

Multiple Choice

What would be the most likely result if an ecosystem received significantly less sunlight over a long period?

• The amount of chemical energy available for the food web would decrease.

• The amount of carbon dioxide used by the ecosystem would increase.

• The amount of water in the ecosystem would increase.

• The amount of matter in the non-living world would decrease.

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How Food Provides Energy

• Food gives organisms energy for life’s processes through a process called cellular respiration.

• Digestion breaks down large food molecules into smaller molecules like glucose for the cells.

• Inside the cell’s mitochondria, glucose reacts with oxygen to release stored chemical energy.

• This energy is captured in ATP, forming water (H₂O) and carbon dioxide (CO₂) waste.

Multiple Choice

What is the main reason organisms need food?

• To get usable chemical energy for life processes.

• To produce oxygen for breathing.

• To release water and carbon dioxide.

• To build mitochondria in their cells.

Multiple Choice

What is the relationship between glucose and ATP in a cell?

• Glucose is used during cellular respiration to produce ATP.

• ATP is broken down during digestion to create glucose.

• Glucose and ATP are both released as waste products.

• Glucose is stored in the mitochondria, while ATP is stored in the blood.

Multiple Choice

If a cell has access to glucose but is deprived of oxygen, what is the most likely effect on the cell's functions?

• The cell will not be able to produce usable energy (ATP) through cellular respiration.

• The cell will start breaking down ATP to produce glucose.

• The cell will release extra carbon dioxide and water.

• The cell's mitochondria will start digesting food directly.

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Food for Growth and Repair

• Food provides the matter your body needs for growth and self-repair.

• This shows the conservation of matter, where atoms are only rearranged.

• Atoms from food are reassembled to form your skin, muscles, and tissues.

• Chemical reactions rebuild food into the complex molecules your body needs.

Multiple Choice

What is the primary role of food in the process of growth and self-repair?

• Energy to move around

• Matter to build new tissues

• Vitamins to fight disease

• Heat to stay warm

Multiple Choice

Which statement best describes how the body uses matter from food for growth?

• The body creates entirely new atoms to build skin and muscles.

• Atoms from food are rearranged to form new molecules and tissues.

• The body converts food directly into skin and muscle without changing it.

• Food molecules are stored in the body until they are needed for energy.

Multiple Choice

Based on the principle of conservation of matter, what is the best explanation for how the atoms in a meal become part of a person's body?

• The atoms from the food are destroyed, and the body creates new atoms to build muscle.

• The atoms from the food are used for energy and then disappear from the body.

• The atoms from the food are reassembled through chemical reactions to become part of the body's tissues.

• The food's molecules are absorbed directly into the body's tissues without any change.

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Common Misconceptions

Misconception	Correction
Plants only perform photosynthesis, not cellular respiration.	Plants perform both photosynthesis and cellular respiration to get energy.
Cellular respiration is the same as breathing.	Breathing is gas exchange; cellular respiration is a chemical process.
Food is 'burned' and disappears in our bodies.	Atoms in food are conserved and rearranged into new molecules like CO2.
Plants create energy from sunlight.	Plants convert light energy from the sun into stored chemical energy.

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Summary

• Photosynthesis uses light energy to convert CO₂ and water into glucose and oxygen.

• Cellular respiration releases stored energy from food, producing ATP, CO₂, and water.

• Atoms in food are rearranged to provide energy for growth and repair.

• Photosynthesis and cellular respiration are an interconnected cycle.

• Animals get matter and energy by eating plants or other animals.

Poll

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