3.3 LESSON Energy in Ecosystems

© 2017 Cengage Learning. All Rights Reserved.

• Energy flows through ecosystems via movement between

trophic levels through food chains and food webs.

– The quality of energy available to organisms decreases as each

successive trophic level is reached, because so much energy (heat) is lost moving from one level to the next.

3.3 What Happens To Energy in an Ecosystem?

Multiple Choice

As energy moves through a food web, the quality of the energy _____.

• increases

• decreases

• stays the same

• tastes pretty good

Drag and Drop

Energy moves through ecosystems between ​

Placeholder

levels through ​

Placeholder

chains and food ​

Placeholder

.

Drag these tiles and drop them in the correct blank above

trophic

food

webs

consumer

pyramid

© 2017 Cengage Learning. All Rights Reserved.

• Food chains

– A sequence of organisms, each of which serves

as a nutritional source for the next

– About 90% energy lost at each link in food chain,

as organisms convert chemical energy from food
to energy needed to live and grow

• Food webs

– A complex network of interconnected food chains

Energy Flows Through Ecosystems in Food Chains and
Food Webs

Fill in the Blank

Only about __% of energy is passed onto the next link in a food chain.

Labelling

Food chains are a sequence of organisms that energy travels through.

Food webs are a complex network of food webs.

Drag labels to their correct position on the image

food web

food chain

© 2017 Cengage Learning. All Rights Reserved.

Energy Flow in a Food Chain

Fill in the Blank

How is energy "lost" at every trophic level?

Reorder

Reorder the following starting with the trophic level that uses sunlight to make food.

• Producers

• Primary Consumers

• Secondary Consumers

• Tertiary Consumers

• Decomposers

1

2

3

4

5

• 1
• 2
• 3
• 4
• 5

© 2017 Cengage Learning. All Rights Reserved.

Feeding Relationships in a Food Web

Match

Match the organisms from the food web to their role.

• phytoplankton

• krill

• squid

• human

producer

primary consumer

secondary consumer

tertiary consumer

• producer

• primary consumer

• secondary consumer

• tertiary consumer

© 2017 Cengage Learning. All Rights Reserved.

A Generalized Pyramid of Energy Flow

Multiple Choice

In most energy pyramids, where would you find the most energy available?

• producers

• primary consumers

• secondary consumers

• tertiary consumers

© 2017 Cengage Learning. All Rights Reserved.

• Gross primary productivity (GPP)

– Rate at which an ecosystem’s producers convert

radiant energy into chemical energy

• Net primary productivity (NPP)

– Rate at which producers use photosynthesis to

produce and store chemical energy, minus the
rate at which they use energy for cellular respiration

• A measure of the rate at which producers make

chemical energy potentially available to consumers

Primary Productivity

Multiple Choice

Gross Primary Productivity (GPP) has to do with...

• how quickly herbivores eat producers

• how quickly carnivores eat herbivores

• how quickly chemical energy is made in the 1st trophic later

• how quickly energy is converted to the 2nd trophic level

Multiple Choice

Which number is always going to be larger?

• GPP

  Gross Primary Productivity

• NPP

  Net Primary Productivity

• could be either

• they are the same

© 2017 Cengage Learning. All Rights Reserved.

• Despite low NPP, oceans produce most of the

world’s biomass because of their vast size.

• Tropical rain forests have high NPP due to

their great variety and abundance of plants.

• Only plant matter represented by NPP is

available as nutrients for consumers.

– The planet’s NPP ultimately limits the number of

consumers that can survive.

Ecosystems Vary in Their Net Primary Productivity (NPP)

Multiple Choice

Where is most of the world's biomass?

• deserts

• oceans

• South Carolina

• rainforests

Reorder

Reorder the following from least to most NPP.

least ------> most

• desert

• ocean

• South Carolina

• rainforest

1

2

3

4

• 1
• 2
• 3
• 4