4. Capturing the Sun's Energy

Capturing the Sun’s Energy

How do producers capture energy and matter?

Vocabulary

Matter: anything that has mass and volume

Producer: an organism that captures energy and matter from its surroundings to produce sugars and
other molecules

Photosynthesis: the process of using energy from the sun and matter from the environment to
produce sugars that store energy in chemical bonds

Chloroplast: a cell structure that uses the sunʼs energy to make sugar through the process of
photosynthesis

Chlorophyll: a green pigment that is important in photosynthesis

Cellulose: the material that forms the rigid walls and support for plant cells

Biomass: the combined mass of the bodies of organisms, which collectively represents stored energy

Biofuel: a material that is made from biomass and releases energy when it is burned

1. Producers Capture Energy and Matter

Matter: anything that has mass and volume

Our bodies and cells are all made of matter and atoms

It takes energy to move our bodies

●We use food as energy but other organisms might use different things

Producer: an organism that captures energy and matter from its surroundings to produce sugars and other
molecules

●Organisms that are able to produce their own food

Producers in Terrestrial Ecosystems

All ecosystems contain many kinds of producers

-Plants and single-celled organisms

Producers in Aquatic Ecosystems

-Aquatic plants & single-celled organisms

Multiple Choice

What do all organisms need to survive, grow, and reproduce?

• Water molecules

• Sunlight and matter

• Gas molecules and sunlight

• Matter and energy

2. Producers Use Photosynthesis

Photosynthesis Takes Place in Chloroplasts

Photosynthesis: the process of using energy from the sun and matter from the
environment to produce sugars that store energy in chemical bonds

Chloroplast: a cell structure that uses the sunʼs energy to make sugar through the
process of photosynthesis

Chlorophyll Absorbs Energy from Light

Chlorophyll: a green pigment that is important in photosynthesis

●Absorbs energy when light shines on it

●Reflects colors of light that it does not absorb - green

●Chloroplasts contain chlorophyll, and leaves contain chloroplasts

2. Producers Use Photosynthesis

Producers Get Matter from Air and Water

Photosynthesis requires water, which plants absorb through their roots

Carbon dioxide found in air is also required for photosynthesis

Light Causes a Chemical Reaction

Carbon dioxide + water + sunlight → sugar + oxygen (photosynthesis)

Open Ended

What two kinds of matter are required for photosynthesis?

3. Discovering Photosynthesis

“How do plants use or produce gases?” -Jan Ingenhousz in the 1700s

●Scientists knew that plants produced something that was important for survival
(later discovered to be oxygen)

●Ingenhousz placed a plant under light conditions and other one under dark
conditions

●Collected and analyzed the bubbles of gas produced under the light conditions

Green parts of plants produce oxygen only when exposed to light

●The plants in the dark didnʼt produce oxygen

Nicolas-Théodore de Saussure found where plants get their mass

●Sealed plants in jars to keep track of the carbon dioxide used by the plant

●Plants get about 70% of their matter from carbon dioxide

Open Ended

Where do plants get their mass?

4. Storing Energy and Matter

Stored Energy and Matter in Organisms

Producers use some of the energy that they capture during photosynthesis right away

●The sugars that producers make during photosynthesis are used as energy and are the building
blocks of complex molecules (like starch or cellulose)

Cellulose: the material that forms the rigid walls and support for plant cells

Producers store some of the energy and matter for later use in the form of more complex molecules

●For when growth or work needs to take place when there isnʼt energy to collect

Stored Energy and Matter in Ecosystems

Other kinds of organisms benefit from photosynthesis by either eating producers or eating other
organisms that eat producers

Biomass: the combined mass of the bodies of organisms, which collectively represents stored energy

Producers create biomass through photosynthesis by capturing matter and energy from nonliving
things and turning it into sugar and energy

Open Ended

Why do producers store some of the sugar they made for later use?

5. Biomass Is a Source of Energy for Humans

How can engineers choose a jet fuel that has enough energy but also has the lowest possible impact on Earth?

Choosing a Fuel for Jets

Criteria: must store as much energy as possible in the lowest possible mass

Fossil Fuels as Jet Fuel

Constraint: must be from renewable resources

Jet fuel was fossil-fuels until the 2000s when they decided they should be renewable resources

Biomass as Jet Fuel

Biofuels as an alternative to jet fuels

Biofuel: a material that is made from biomass and releases energy when it is burned

Manufacturers make biofuels by taking plant biomass and using chemical reactions to break it down into sugars
again

5. Biomass Is a Source of Energy for Humans

Constraints Help Identify the Best Source of Biomass

Has to be renewable and renewable within a reasonable time frame

Must be affordable

Urban wastes are the highest energy, renewable resources

●Grass cuttings, food scraps, cardboard, wood scraps

●Generate carbon dioxide when burned

Biofuels address the needs of the airline industry by providing a low-cost and
renewable source of fuel that also stores enough energy to power flight when it is
burned in a jet engine

Open Ended

List the criteria that engineers consider for jet fuel:

Open Ended

List the constraints that engineers consider for jet fuel: