MS-LS1-7: Food, Energy, and Growth

MS-LS1-7

Food, Energy, and Growth

Middle School

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Learning Objectives

• Model how chemical reactions break down and rearrange food molecules for growth and energy.

• Explain how cellular respiration releases energy from food molecules and oxygen.

• Describe how atoms in food rearrange to form new molecules for growth.

• Compare how producers and consumers get food for their chemical reactions.

Key Vocabulary

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Consumer

A consumer is an organism that gets its energy by feeding on other organisms in a food chain.

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Producer

A producer is a living thing, like a plant, that creates its own food, usually through photosynthesis.

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Chemical Reaction

A chemical reaction is a process where atoms are rearranged to create entirely new substances with different properties.

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Molecule

A molecule is the smallest particle of a substance, made up of two or more atoms bonded together.

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Atom

An atom is the fundamental building block of all matter and the smallest unit of a chemical element.

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Cellular Respiration

Cellular respiration is the process cells use to convert nutrients from food into usable energy for life functions.

Key Vocabulary

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Conservation of Matter

This principle states that matter is not created or destroyed during any chemical reaction.

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Producers and Consumers

Producers

• Organisms that create their own food are also called autotrophs.

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

• This group includes plants, algae, and some kinds of bacteria.

Consumers

• Organisms that cannot make their own food are called consumers or heterotrophs.

• They get all of their energy by eating other organisms.

• This includes animals that eat plants or other animals for food.

Multiple Choice

What is the fundamental difference between producers and consumers?

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

• Producers are always animals, while consumers are always plants.

• Producers get energy from eating other organisms, while consumers create their own food.

• Producers live on land, while consumers live in water.

Multiple Choice

How do organisms like plants and algae create their own food?

• By eating other organisms for energy.

• Through a process called photosynthesis.

• By absorbing sunlight through their skin.

• By breaking down dead plant material.

Multiple Choice

Scientists discover a new organism that survives by eating only algae. Based on its source of energy, how should it be classified and why?

• As a producer, because it lives in the water like algae.

• As a consumer, because it gets energy by eating another organism.

• As a producer, because it is a type of bacteria.

• As a consumer, because it is a type of animal.

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How Food Molecules are Rearranged

• Food is made of complex molecules with carbon, hydrogen, and oxygen atoms.

• Chemical energy is stored in the bonds of these food molecules.

• When you eat, chemical reactions begin to break down the food molecules.

• Atoms rearrange to form new molecules for the body’s growth and energy.

Multiple Choice

What primarily happens to the molecules in food after you eat it?

• They are stored whole in the body for later use.

• They are immediately converted into heat energy.

• They are broken down and their atoms are rearranged to form new molecules.

• They are expelled from the body without any changes.

Multiple Choice

How does the breakdown of food molecules provide the body with energy?

• The atoms themselves are converted directly into energy.

• Breaking the chemical bonds in food molecules releases stored energy.

• The body creates energy first to break down the food molecules.

• Oxygen atoms are the only source of energy in food.

Multiple Choice

If a person's body could break down food molecules but was unable to rearrange the atoms, what would be the most likely result?

• The body would get energy but would not be able to build materials for growth.

• The body would get more energy because it's a simpler process.

• The food molecules would pass through the body completely undigested.

• The atoms from the food molecules would be destroyed.

Aerobic Cellular Respiration

• This process releases stored chemical energy from food molecules like sugar.

• It uses oxygen to produce carbon dioxide, water, and usable energy.

• A large amount of energy is also lost to the environment as heat.

Multiple Choice

What is the primary purpose of aerobic cellular respiration?

• To create oxygen for an organism to breathe

• To release stored chemical energy from food molecules

• To produce sugar by using carbon dioxide and water

• To use heat from the environment to create energy

Multiple Choice

Which statement best describes the process of aerobic cellular respiration?

• It uses carbon dioxide to produce oxygen and sugar.

• It uses energy to produce oxygen and water.

• It uses oxygen to produce carbon dioxide, water, and energy.

• It uses sugar to produce only heat and oxygen.

Multiple Choice

During exercise, an organism's body temperature increases. What is the best explanation for this observation?

• The process creates extra water, which warms the body.

• The process uses up all the oxygen in the body.

• Some energy from the process is lost to the environment as heat.

• The carbon dioxide produced by the process traps heat.

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Conservation of Matter

• Atoms are not created or destroyed during a chemical reaction.

• The atoms in your food are rearranged to build your body.

• All matter in an organism comes from the food it eats.

• Atoms are released as waste, like carbon dioxide (CO₂).

Multiple Choice

Which statement best describes the law of conservation of matter?

• Some atoms are lost during chemical reactions.

• New atoms are created to build new things.

• Atoms can be converted into pure energy.

• Atoms are not created or destroyed, only rearranged.

Multiple Choice

How can the atoms from a sugar molecule you eat become part of your muscles?

• The body's cells destroy the sugar atoms to release energy.

• Atoms from the sugar are reassembled to form parts of the body.

• The body creates new, different atoms after consuming sugar.

• Sugar atoms are converted directly into energy and disappear.

Multiple Choice

If a person eats a meal and their body processes it, what must be true about the matter from the meal?

• The food's mass is completely destroyed as it is converted to energy.

• The person's body will gain more mass than the food provided.

• The total mass of the person's body and waste products will equal the original mass of the food.

• Most of the food's mass will be lost and will not be accounted for.

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The Relationship Between Photosynthesis and Respiration

Multiple Choice

What is the primary purpose of aerobic respiration?

• To break down sugar molecules to release chemical energy.

• To use energy from the sun to build sugar molecules.

• To create oxygen and food molecules for producers.

• To form a vital cycle using only water and sunlight.

Multiple Choice

How do photosynthesis and aerobic respiration work together in a cycle?

• Each process uses the materials produced by the other.

• Both processes use the sun's energy to create sugar.

• Both processes break down sugar to release energy.

• One process happens in producers and the other happens only in the soil.

Multiple Choice

If a large number of producers, like forests, were removed from an ecosystem, what is the most likely effect on the materials available for consumers?

• The oxygen and sugar needed by consumers for respiration would decrease.

• The amount of energy released by producers would increase.

• The amount of sugar broken down by producers would increase.

• The oxygen and sugar available for photosynthesis would increase.

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Common Misconceptions

Misconception	Correction
Plants only photosynthesize; animals only respire.	Plants perform both photosynthesis and cellular respiration to get energy.
Respiration is the same as breathing.	Breathing moves air. Respiration is a chemical reaction inside cells.
Energy is created during respiration.	Stored chemical energy in food is converted into usable energy.
Matter is lost when food is eaten.	Matter is conserved. Atoms are rearranged into new molecules like CO2.

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Summary

• In chemical reactions, atoms in food molecules are rearranged to form new molecules.

• New molecules support growth or are broken down to release energy.

• Cellular respiration uses oxygen to release stored chemical energy from food.

• Matter is conserved because atoms are only rearranged, not lost.

• Photosynthesis and respiration form a cycle of reactants and products.

• Respiration: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + usable energy.

Poll

On a scale of 1-4, how confident are you about how food is used for matter and energy in an organism?

• 1 (Not confident at all)

• 2 (A little confident)

• 3 (Mostly confident)

• 4 (Very confident)