6th Grade Science

Chapter 13 The

Nonliving Environment

Notes Section 13.3

Chimney Rock, North Carolina

• Can matter be recycled?• Matter can be recycled over and over but this

process requires energy.• Can energy be recycled?• Energy is not recycled, but it is converted from one

form to another.

Key Questions 1

• How do producers convert energy into food?• Most producers convert light energy into food. Some

producers convert chemicals like sulfur into food.• What is chemosynthesis?• The production of energy-rich nutrient molecules

from chemicals is called chemosynthesis.

Key Questions 2

The Tadpole Galaxy

Chemosynthesis

• Not all producers rely on light for energy.• During the 1970s, scientists exploring

the ocean floor were amazed to find communitiesat a depth of almost 3.2 km and living in total darkness.

• What is a food chain?• A food chain shows how matter and energy pass

from one organism to another. • What is a food web?• A food web is made up of many different food

chains.

Key Questions 3

The Sombrero Galaxy

Food Chains• Carnivores and omnivores—animals that eat

other consumers—are the third and higher steps of food chains.

• What is an energy pyramid?• Energy pyramids show the amount of energy

available at each feeding level.• How does the available energy change at each level

of the energy pyramid?• The amount of available energy decreases from the

base to the top of the energy pyramid.

Key Questions 4

• A food web is a model that shows all thepossible feeding relationships among the organisms in a community.

Food Webs

• A food web is made up of many different food chains.

• An energy pyramid shows the amount ofenergy available at each feeding level in an ecosystem.

Available Energy

• The bottom of the pyramid, which represents all of the producers, is the first feeding level.

Available Energy

• Only about ten percent of the energy available at each feeding level of an energy pyramid is transferred to next higher level.

• As you move up the pyramid, the transfer of energy is less efficient and each level becomes smaller.

1. Compare and contrast a food web and an energy pyramid.

2. Explain why there is a limit to the number of links in a food chain.

3. Use your knowledge of food chains and energy pyramid to explain why the number of mice in a grassland ecosystem is greater than the number of hawks.

Questions Section 13.3