Energy Flow Through Trophic LevelsBiology 12(C)

Energy• Originates from sun• Transferred between organisms• Leaves ecosystem as motion and heat

Biotic & Abiotic Factors• Biotic factors – the living components of the environment EX:• Abiotic factors – the nonliving components of the environ

EX:

Autotrophs & Heterotrophs• Heterotroph – organism that must acquire energy by consuming other organisms• Autotroph – organism that is able to capture energy from the sun to make it’s own food

ATP (Adenine Tri Phospate)• Organisms use chemical energy from food • Breaking down carbohydrate bonds releases energy• Stored in Bonds of (ATP)• Draw in notebook ATP

Organisms survive by:• Producing food or feeding on other

organisms

Flow of matter and energy: • Organisms eat each other to get energy

(except plants)• Instead of saying “bear eats fish” we say “the energy in the fish is transferred to the bear”

Energy Flow Through Trophic Levels

Trophic level – distinct level of feeding within ecosystem• Species at each level vary in different

communities

Trophic levels:• Producer• Consumer– Primary– Secondary– Tertiary (or top)

• Decomposer

Trophic Levels

Producer – produce own food, first or lowest trophic level• Example: plants

Primary consumer – first-order consumer, eats a producer• Example:

grasshopper

Trophic Levels

Primary consumer – first-order consumer, eats a producer• Example:

grasshopper

Secondary consumer – second-order consumer, eats primary consumer• Example: lizard

Trophic Levels

Secondary consumer – second-order consumer, eats primary consumer• Example: lizard

Tertiary consumer – third-order consumer, eats secondary consumer• Example: snake

Trophic Levels

Decomposer (saprobe) – breaks down dead plant and animal matter and returns nutrients to soil– Examples: bacteria and fungi

Trophic Levels

You will have a quiz in 5 minutes….STUDY!

• On a separate sheet of paper answer the following:

1. What are biotic factors and list 22. What are abiotic factors and list 23. What does this picture show?

4. Make a pyramid and divide it into half (a top half and a bottom half). Places the words “producer” and “consumer” into the part of the pyramid where they apply to and define each next to the word in the pyramid.

Trophic Energy Quiz 1 (10pts)

Sometimes consumers are referred to by type of food they eat rather than trophic level:• Herbivore – eats only plants– Examples: deer, rabbit

• Carnivore – eats only animals– Examples: lion, shark

• Omnivore – eats plants and animals– Examples: bear, human

• Scavenger – feed only on dead organisms– Examples: vulture, hyena

Trophic Levels

Food chain – sequence of organisms feeding on one another at a lower trophic level

Producer Primary Consumer Secondary Consumer

Food Chains

• In this food chain, which is the …Producer-1* Primary Consumer-2* Primary Consumer-3* Primary Consumer-4* Primary Consumer-

Food web – network of interacting food chains• Most organisms eat more than one food type• Ecosystems usually contain more than one

food chain• Complex relationships between trophic

levels

Food Webs

• Highlight 4 different food chains and put them in order of Producer, 1 C, 2 C, 3 C, 4 C , ….

• What do they have in common, different, are any organisms on two different trophic levels?

You will have a quiz in 5 minutes….STUDY!

• On a separate sheet of paper answer the following:

1. Define and give an example for:- producer- herbivore- carnivore- omnivore

- scavenger- decomposer

2. Copy the food web at right and label each organism as one of the above based only on the data in the food web.

Trophic Energy Quiz 2 (20pts)

• Which organisms are the producers?– Pond weed and

algae

• Which organisms are the secondary consumers?– Perch, minnow,

and dragonfly

• Which organisms do frogs eat?– Minnow and

dragonfly

Complex Food Web

Food Webs

• Which consumers feed on bivalves?– Sea ducks, tundra swans, and herbivorous ducks

• Which consumers feed on zooplankton?– Small fish, bivalves

Food Webs

Ecological pyramid – used to visualize food chains• Pyramid of energy – amount of energy in

bodies of organisms at each trophic level• Pyramid of numbers – number of organisms

feeding at each trophic level• Pyramid of biomass – total mass of dry,

organic matter at each trophic level

Ecological Pyramids

Matter and Energy cycles through the ecosystem when one organism is passed to another when eaten

Matter and Energy cycles through the ecosystem when one organism is passed to another when eaten

Energy decreases up the pyramid:• Grass captures

sun’s energy• Rabbit obtains

10% of stored energy in grass

• Snake obtains 10% of stored energy in rabbit

• Eagle receives 10% of stored energy snake

Pyramid of Energy

Pyramid of Energy

1 kcal

10 kcal

100 kcal

1000 kcal

Numbers decrease up the pyramid:• More individual

organisms at lower trophic levels

• Fewer individuals at higher trophic levels

Pyramid of Numbers

Pyramid of Numbers

Biomass decreases up the pyramid:• Greatest biomass

at producer level• Least biomass at

tertiary consumer level

Pyramid of Biomass

Tertiary Consumer (1.5 grams/square meter)

Secondary Consumer (11 grams/square meter)

Primary Consumer (37 grams/square meter)

Pyramid of Biomass

Producers807 grams/square meter

Decomposer5 grams/square meter

Use the 10% rule to see how much energy will get transferred!Q: If the plants start with 100J of energy how much is in all the rest of the levels?Q: If the heron received 3J of energy how much did the plant start with?

Use the 10% rule to see how much energy will get transferred!Q: If the primary consumers have 676J of energy how much is in all the rest of the levels?Q: If the bass received 1 J of energy how much did the plant start with?

You will have a quiz in 5 minutes….STUDY!

Draw a trophic pyramid to solve each question:1. If the secondary consumers have 2 J

how much is in all the rest of the levels?

2. If the bass received 100 J of energy how much did the plant start with?

3. Plants start with 1005 J of energy how much is in all of the levels?

4. The heron received 3,500 J how much did the plant start with?

5. Plants started with 500 J how much did the tertiary consumer get?

Trophic Energy Quiz 3 (10pts)