Matter and Energy in Ecosystems

Matter and Energy in Ecosystems

Middle School

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Learning Objectives

• Define photosynthesis and cellular respiration and describe their relationship.

• Model the flow of energy and the cycling of matter in an ecosystem.

• Differentiate between producers, consumers, and decomposers and their important roles.

• Explain how resource availability affects the growth and survival of organisms.

• Describe how essential matter is conserved as it cycles through an ecosystem.

Key Vocabulary

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Ecosystem

An ecosystem includes all of the living and nonliving things interacting in a specific area.

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Biotic Factors

Biotic factors are all the living or once-living components of an ecosystem, such as plants and animals.

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Abiotic Factors

Abiotic factors are the nonliving chemical and physical parts of an ecosystem, like sunlight, water, and soil.

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Photosynthesis

Photosynthesis is the process where plants use sunlight and water to create their own food for energy.

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Cellular Respiration

Cellular respiration is the process by which organisms break down glucose to release usable energy as ATP.

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Producer

A producer is an organism, like a plant, that can produce its own food through photosynthesis.

Key Vocabulary

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Consumer

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

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Decomposer

A decomposer is an organism that breaks down dead organic material, recycling nutrients back into the ecosystem.

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Food Web

A food web is a detailed model that illustrates the complex, interconnected feeding relationships between different organisms.

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Resource Availability

Resource availability describes the supply of necessary materials like food, water, and shelter that organisms need to survive.

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Competition

Competition is the struggle between organisms for the same limited resources, such as food, territory, or mates.

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Conservation of Matter

Conservation of matter means that matter is only cycled through an ecosystem, not created or destroyed.

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Photosynthesis: Capturing the Sun's Energy

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Multiple Choice

What is the primary purpose of photosynthesis?

• To convert light, water, and carbon dioxide into food for the plant.

• To absorb nutrients from the soil through the roots.

• To release oxygen into the atmosphere for animals to breathe.

• To create green pigment to make the leaves colorful.

Multiple Choice

What is the specific role of chlorophyll within the chloroplasts during photosynthesis?

• It absorbs the light energy needed to power the process.

• It directly combines water and carbon dioxide into a new molecule.

• It serves as the location for storing the finished glucose.

• It is the final food product that the plant consumes.

Multiple Choice

Based on the information provided, what would most likely happen if a healthy plant were moved into a completely dark room for a week?

• Glucose production would stop because there is no light energy for chlorophyll to absorb.

• The plant would start using carbon dioxide and water to make food without light.

• The chloroplasts would produce more chlorophyll to make up for the lack of light.

• The plant would find another way to create food using only water.

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Cellular Respiration: Releasing Stored Energy

• Cellular respiration converts food energy into a usable form of energy called ATP.

• The first step, glycolysis, occurs in the cytoplasm and produces a little ATP.

• The second step in the mitochondria uses oxygen to produce lots of ATP.

• This process releases water (H₂O) and carbon dioxide (CO₂) as waste.

Multiple Choice

What is the main purpose of cellular respiration?

• To create water and carbon dioxide for the body

• To convert food into a usable form of energy for cells

• To break down ATP into glucose in the cytoplasm

• To store energy by creating complex food molecules

Multiple Choice

How does the second step of cellular respiration primarily differ from glycolysis?

• The second step occurs in the cytoplasm and breaks down glucose.

• The second step occurs in the mitochondria and requires oxygen.

• The second step produces a small amount of ATP without oxygen.

• The second step converts ATP directly into glucose for storage.

Multiple Choice

Based on the process described, what would most likely happen if a cell were deprived of oxygen?

• The cell's production of ATP would significantly decrease.

• The process of glycolysis would immediately stop.

• The cell would produce more carbon dioxide as waste.

• The mitochondria would begin to produce their own oxygen.

The Relationship Between Photosynthesis & Respiration

• Photosynthesis and respiration are opposite reactions that form a cycle.

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

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

Multiple Choice

What does a plant produce during photosynthesis?

• Food and oxygen

• Carbon dioxide and water

• Light energy and food

• Oxygen and water

Multiple Choice

What is the primary relationship between photosynthesis and respiration?

• They are opposite processes that form a cycle

• They are the exact same chemical reaction

• Photosynthesis happens during the day and respiration happens at night

• Photosynthesis creates energy and respiration uses water

Multiple Choice

If a plant were placed in a sealed, dark container, what would most likely happen to the levels of oxygen and carbon dioxide inside?

• Oxygen would decrease, and carbon dioxide would increase.

• Oxygen would increase, and carbon dioxide would decrease.

• Both oxygen and carbon dioxide would increase.

• Both oxygen and carbon dioxide would stay the same.

Energy Roles in an Ecosystem

• Producers, like plants, make their own food from sunlight.

• Consumers get energy by eating other organisms.

• Decomposers break down dead matter and recycle nutrients.

Multiple Choice

What do the terms producer, consumer, and decomposer describe in an ecosystem?

• The different ways organisms get energy

• The different types of plants in a habitat

• The way sunlight creates energy for all life

• The process of animals hunting for food

Multiple Choice

How is the way a producer gets energy different from the way a consumer gets energy?

• Producers make their own food, while consumers eat other organisms to get energy.

• Consumers make their own food, while producers eat other organisms to get energy.

• Producers and consumers both get energy by breaking down dead matter.

• Producers and consumers both get their energy directly from sunlight.

Multiple Choice

Based on their role in the ecosystem, what would most likely happen if there were no decomposers?

• Dead matter would accumulate, and nutrients would not be returned to the ecosystem.

• Producers would stop making their own food from sunlight.

• Consumers would have an unlimited supply of food.

• The ecosystem would have more energy available for producers.

Modeling Matter and Energy Transfer

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Food Chain

• This is a simple, linear model showing a single path of energy.

• The arrows point in the direction that the energy is flowing.

• For example: Grass → Rabbit → Fox is one food chain.

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Food Web

• A more realistic model showing many interconnected food chains in an ecosystem.

• It shows how matter and energy move between many different organisms.

• This shows that organisms often have multiple different food sources to eat.

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Energy Pyramid

• This model shows energy flows out of a system, while matter cycles.

• Only about 10 percent of energy gets passed to the next level.

• The rest of the energy is used for life or lost as heat.

Multiple Choice

Which statement best describes a food chain?

• It shows a single, direct path of energy flow.

• It includes all organisms in an ecosystem.

• It shows how matter is recycled by decomposers.

• It explains why energy is lost as heat.

Multiple Choice

What is the primary difference between a food web and a food chain?

• A food web shows multiple interconnected energy paths, while a food chain shows only one.

• A food chain shows how 10% of energy is lost, while a food web does not.

• A food web includes producers, while a food chain only includes consumers.

• A food chain shows the flow of matter, while a food web shows the flow of energy.

Multiple Choice

In an ecosystem, producers have 10,000 units of energy. The herbivores that eat them only receive about 1,000 units of energy. Which statement best explains this outcome?

• The producers did not create enough energy.

• The energy was transferred to a different food web.

• Most of the energy was used for life processes or lost as heat.

• The energy was destroyed and did not get passed on.

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Resource Availability and Competition

• Resource availability is the amount of accessible food, water, and space.

• Organism growth and reproduction are limited by access to these resources.

• When resources are abundant, populations can grow larger and reproduce more.

• Scarce resources cause competition, which can decrease the population size.

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Multiple Choice

Which statement best defines 'resource availability'?

• The number of organisms living in a specific habitat.

• The amount of accessible food, water, and space in an area.

• The way organisms compete with one another for survival.

• The process of reproduction within a population.

Multiple Choice

What is the relationship between resource availability and population size?

• Resource availability only affects an organism's size, not its population.

• When resources are abundant, populations tend to grow larger.

• The amount of space is the only resource that limits population growth.

• Competition for resources only happens when a population is small.

Multiple Choice

If a long drought significantly reduces the amount of food and water in a habitat, what is the most likely outcome for a large population of animals living there?

• The organisms will stop needing water, and the population will grow.

• Competition will increase, and the population is likely to decrease.

• The organisms will learn to share the limited resources, and the population will stay the same.

• The amount of food and water will increase to support the population.

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Conservation of Matter in Ecosystems

• Matter is not created or destroyed, it only changes its form.

• Atoms cycle between living (biotic) and nonliving (abiotic) parts of an ecosystem.

• A carbon atom in CO₂ can become part of a plant, then an animal.

• Decomposers return atoms from dead organisms to the soil, air, and water.

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Multiple Choice

What does the principle of conservation of matter state?

• Matter is not created or destroyed, it only changes form.

• New matter is constantly created by decomposers.

• Matter can only be found in living things.

• Atoms are lost when organisms die.

Multiple Choice

What is the relationship between decomposers and the nonliving parts of an ecosystem?

• They cycle atoms from dead organisms back to the soil, air, and water.

• They create new atoms for plants to use.

• They transfer atoms from the air directly to animals.

• They turn matter into energy for living things.

Multiple Choice

Based on the flow of matter described, what would happen if all decomposers were suddenly removed from an ecosystem?

• The atoms in dead plants and animals would not be recycled for new life to use.

• Animals would learn to get carbon atoms directly from the air.

• The total amount of matter in the ecosystem would slowly decrease.

• Plants would stop needing atoms from the soil to grow.

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The Water and Nitrogen Cycles

The Water Cycle

• ​Water is essential for life and continuously cycles through an ecosystem as an abiotic factor.

• ​​Evaporation turns liquid water into a gas, while condensation forms clouds from this gas.

• ​Precipitation is the process of water falling back to Earth in forms like rain or snow.

The Nitrogen Cycle

• ​All organisms need nitrogen to make proteins, which are vital for building cells and tissues.

• ​​Nitrogen-fixing bacteria convert atmospheric nitrogen into usable compounds that are found in the soil.

• ​Decomposers return nitrogen to the soil by breaking down waste and the remains of dead organisms.

Multiple Choice

What is the fundamental purpose of the water and nitrogen cycles in an ecosystem?

• To continuously move essential substances for life through an ecosystem.

• To create new sources of water and nitrogen for organisms.

• To turn abiotic factors into biotic factors for consumption.

• To prevent evaporation and precipitation from occurring.

Multiple Choice

What is the relationship between bacteria and proteins in the nitrogen cycle?

• Nitrogen is converted into usable forms by bacteria, which plants need to make proteins.

• Decomposers turn proteins directly into atmospheric nitrogen for plants to use.

• Nitrogen is a gas that plants absorb directly from the air to build cells.

• The nitrogen cycle is the process of water falling back to Earth as rain.

Multiple Choice

If a chemical spill eliminated most of the nitrogen-fixing bacteria and decomposers in an area, what would be the most likely impact on the ecosystem?

• The amount of usable nitrogen in the soil would decrease, limiting the material available for organisms to build proteins.

• The amount of water evaporating from the soil would increase significantly.

• Decomposers would take over the job of converting atmospheric nitrogen.

• Organisms would adapt to use atmospheric nitrogen directly to make proteins.

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The Carbon and Oxygen Cycles

The Carbon Cycle

• ​Carbon is a key component of all living organisms.

• ​Plants use carbon dioxide (CO₂) from the atmosphere for photosynthesis.

• ​Respiration and decomposition release carbon dioxide back into the atmosphere.

The Oxygen Cycle

• ​Oxygen is essential for animals and other organisms to breathe.

• ​​It is released into the atmosphere by plants during photosynthesis.

• ​Most living things take in oxygen to perform cellular respiration.

Multiple Choice

Which process do plants use to take in carbon dioxide from the atmosphere?

• Photosynthesis

• Respiration

• Decomposition

• Breathing

Multiple Choice

How are the carbon and oxygen cycles connected through living organisms?

• Photosynthesis releases the oxygen that most organisms need for respiration.

• Both photosynthesis and respiration release carbon dioxide into the atmosphere.

• Plants perform photosynthesis, while animals perform decomposition.

• Respiration and photosynthesis are two separate cycles that do not affect each other.

Multiple Choice

What would be the most likely impact on the atmosphere if a large number of plants were suddenly removed from an ecosystem?

• Carbon dioxide levels would increase, and oxygen levels would decrease.

• Carbon dioxide levels would decrease, and oxygen levels would increase.

• Both carbon dioxide and oxygen levels would increase.

• Both carbon dioxide and oxygen levels would remain the same.

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Common Misconceptions

Misconception	Correction
Plants only perform photosynthesis, not cellular respiration.	Plants use photosynthesis for food and respiration for energy.
Energy is cycled through an ecosystem.	Energy flows in one direction, while matter is cycled.
New matter is created to support ecosystem growth.	Growth is supported by the recycling of existing matter.
Decomposers are bad for an ecosystem.	Decomposers are essential because they recycle vital nutrients.

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Summary

• Energy flows in one direction, while matter is conserved and cycled.

• Photosynthesis uses CO₂ to create food; respiration releases energy from food.

• Producers, consumers, and decomposers each have a critical role in this transfer.

• A population’s growth is limited by resource availability, which causes competition.

Poll

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

• 1 - Not confident at all

• 2 - A little confident

• 3 - Mostly confident

• 4 - Very confident