1. Energy Flow Through Trophic Levels
Biology 12(C)

2. 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:

3. 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

4. Energy Flow Through Trophic Levels
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”
Individual organisms within a community survive by either producing their own food or by feeding on other organisms.
The flow of matter and energy in food is transferred from one organism to another as one organism consumes another. This process is part of an organized system of energy flow through ecosystems.

5. 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
A trophic level is a distinct level of feeding within an ecosystem. The particular species at each level vary in different communities, however, most ecosystems have similar trophic levels. The common tropic levels are producers, consumers, and decomposers.

6. Trophic Levels
Producer – produce own food, first or lowest trophic level
Example: plants
Primary consumer – first-order consumer, eats a producer
Example: grasshopper
Producers synthesize, or produce, their own food. Producers are found in the first or lowest trophic level. An example of a producer is a plant, which makes it own food through the process of photosynthesis.
A consumer must eat other organisms for food. The primary consumer, also called a first-order consumer, eats a producer. For example, a grasshopper eats grass.

7. Trophic Levels
Primary consumer – first-order consumer, eats a producer
Example: grasshopper
Secondary consumer – second-order consumer, eats primary consumer
Example: lizard
The secondary consumer, or second-order consumer, eats the primary consumer. For example, a lizard eats the primary consumer, or grasshopper in this case. The lizard is the second-order consumer.

8. Trophic Levels
Secondary consumer – second-order consumer, eats primary consumer
Example: lizard
Tertiary consumer – third-order consumer, eats secondary consumer
Example: snake
The tertiary, or third order, consumer eats the secondary consumer. In this example, the snake is the tertiary consumer eating a lizard. The last consumer in a food chain is called a top consumer. If nothing preyed on this snake, it would be a top consumer.
Different food chains can have different numbers of consumers, however most food chains end at the third or fourth consumer.

9. Trophic Levels
Decomposer (saprobe) – breaks down dead plant and animal matter and returns nutrients to soil
Examples: bacteria and fungi
The decomposer, or saprobe, breaks down dead plant and animal matter and returns nutrients to the soil. Bacteria and some types of fungi, like these mushrooms, are examples of decomposers.

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

11. Trophic Energy Quiz 1 (10pts)
On a separate sheet of paper answer the following:
What are biotic factors and list 2
What are abiotic factors and list 2
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.

12. Trophic Levels
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
Sometimes consumers are referred to by the type of food they eat rather than their trophic level. Herbivores, such as deer and rabbits, eat only plants.
Carnivores, such as lions and sharks, eat only animals. Omnivores eat both plants and animals. Examples of omnivores are bears and humans.
Scavengers, such as hyenas and vultures, feed only on dead organisms.

13. Food Chains
Food chain – sequence of organisms feeding on one another at a lower trophic level
Producer Primary Consumer Secondary Consumer
A food chain illustrates a sequence of one organism feeding upon another at a lower trophic level. Here is an example of a simple food chain containing three trophic levels. In food chains, the arrow always points at the “eater”.
Grass is at the first trophic level. Grass, a producer, produces its own food through photosynthesis. The impala, at the second trophic level, is the primary consumer. The impala eats the producer. The lion, at the third trophic level, is the secondary consumer. The lion eats the primary consumer, or impala, in this case. Since nothing preys on the lion, it is also the top consumer.

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

15. Food Webs 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
A food web is a network of interacting food chains.
Since most organisms eat more than one food type, ecosystems usually contain more than one food chain. This results in complex relationships between trophic levels.

16. 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?

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

18. Trophic Energy Quiz 2 (20pts)
On a separate sheet of paper answer the following:
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.

19. Food Webs Which organisms are the producers? Complex Food Web
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
Here is another way to illustrate this complex food web. Let’s try to analyze this food web by answering some questions.
Which organisms are the producers? The producers are the organisms at the first trophic level that make their own food. Looking at this food web, the producers are the pond weed and algae.
Which organisms are the secondary consumers?
The secondary consumers eat the primary consumers. In this food web, the perch, minnow, and dragonfly are the secondary consumers.
Which organisms do frogs eat?
Remembering that the arrows always point at the eaters, this food web illustrates that the frog eats both minnows and dragonflies.

20. Food Webs Which consumers feed on bivalves?
Sea ducks, tundra swans, and herbivorous ducks
Which consumers feed on zooplankton?
Small fish, bivalves
By analyzing this food web, we can answer these questions.
Which consumers feed on bivalves? Remember that arrows point to the eaters. The consumers that feed on bivalves are the sea ducks, the herbivorous ducks, and tundra swans.
Which consumers feed on zooplankton? The consumers that feed on zooplankton are the primary consumers and will have arrows pointing to them from the zooplankton. In this food web, small fish and bivalves eat zooplankton.

21. Ecological Pyramids 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
An ecological pyramid is used to visualize information about a food chain. There are three major types of ecological pyramids.
A pyramid of energy illustrates the amount of energy measured in calories contained in the bodies of organisms at each trophic level.
A pyramid of numbers illustrates the number of organisms feeding at each trophic level.
A pyramid of biomass illustrates the total mass of dry, organic matter at each trophic level.

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

23. Pyramid of Energy Energy decreases up the pyramid: Pyramid of Energy
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
1 kcal
10 kcal
100 kcal
When grass grows in the sun, it captures some of the sun’s energy. This stored energy is measured in calories. All of this energy is not passed on to the hungry rabbit that eats this plant. The amount of energy stored in the grass is less than the grass initially got from the sun. The majority, usually about 90%, of the energy the grass received from the sun was used for metabolism by the grass, generating work and heat.
When the rabbit eats the grass, it receives only 10% of the energy the grass captured from the sun. While no energy is actually destroyed, ecologists often say that energy has been lost from the food web. This energy has actually been turned into work and heat.
The snake that eats the rabbit receives only 10% of the energy the rabbit received from grass. The rabbit used most of energy gained from plant for its own metabolic needs.
The eagle that eats the snake receives only 10% of the energy the snakes received from the rabbit. The snake used most of the energy gained from the rabbit for its own metabolic needs.
As each trophic level consumes 90% of the energy stored in the trophic level below it, there is less and less energy available as trophic levels increase.
1000 kcal

24. Pyramid of Numbers Numbers decrease up the pyramid: Pyramid of Numbers
More individual organisms at lower trophic levels
Fewer individuals at higher trophic levels
Pyramid of Numbers
This same ecological pyramid can by used to illustrate a pyramid of numbers. This type of pyramid shows the relative numbers of individuals at each trophic level. Remember that organisms at each trophic level only incorporate about 10% of the stored energy from the preceding level. Because of this, each trophic level can typically support fewer and fewer organisms.
In most ecosystems, more individual organisms are at the lower trophic levels. There are fewer individuals at the higher trophic levels.
In ecosystems in which the producers are very large, such as trees in forests, there may be fewer individual producers then primary consumers.

25. Pyramid of Biomass 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)
Decomposer
5 grams/square meter
Biomass is the amount of dry, organic matter at each trophic level. Imagine that all of the water has been removed from the organisms at each trophic level. How much would each trophic level weigh?
Remember that only 10% of energy is passed onto the next trophic level. Because of this, there is typically less biomass at each trophic level.
Producers
807 grams/square meter

26. 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?

27. 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?

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

29. Trophic Energy Quiz 3 (10pts)
Draw a trophic pyramid to solve each question:
If the secondary consumers have 2 J how much is in all the rest of the levels?
If the bass received 100 J of energy how much did the plant start with?
Plants start with 1005 J of energy how much is in all of the levels?
The heron received 3,500 J how much did the plant start with?
Plants started with 500 J how much did the tertiary consumer get?