Due: ________________
Study Guide: Energy Transfer
(food chains, food webs, and energy pyramids)
.
If you have internet or internet access, you may want to visit:
http://www.sheppardsoftware.com/content/animals/kidscorner/foodchain/foodchain2.htm
1- Using the following food chain, answer the questions below.
Grass 
Rabbit  Fox
a. What type of organism is the grass? ______Producer___________
b. Which animal is a herbivore or primary consumer? __________rabbit_________
c. What would happen to the population of rabbits, if the population of foxes increased (got bigger)?
The rabbit population would decrease.
2- Construct a food chain. Label the (1) producer, (2) primary consumer, (3) secondary consumer, and (4)
tertiary consumer. Remember to use arrows..
An owl eats a snake, the snake eats a squirrel, the squirrel ate a nut.
Nut-------->squirrel-------------->snake------------------->owl
Producer primary consumer secondary consumer
tertiary consumer
3- Using the food chain from question 2, construct an energy pyramid.
Owl
snake
Squirrel
Nuts
a. Which animal has the most amount of available energy?
_______squirrel_____________
b. Which animal has the least amount of available energy?
__________owl__________
4- Use the food web below to answer the questions.
a. What is the producer? grass
b. What are the primary consumers? Grasshopper, rabbit, mouse
c. What are the secondary consumers? Kookaburra, snake
d. What are the tertiary consumers? Kookaburra, Wedge Tailed Eagle
e. What is the top predator? Wedge Tailed Eagle.
5- Construct one food chain that you see in the food web. Answers will vary
6- Using your food chain above, construct an energy pyramid. Answers will vary
Trophic Levels
The feeding positions in a food chain or web are called trophic levels. The different trophic levels are defined in
the Table below. Examples are also given in the table. All food chains and webs have at least two or three trophic
levels. Generally, there are a maximum of four trophic levels. Many consumers feed at more than one trophic
level.
Table: 1
Trophic Level
Where It Gets Food
Example
1st Trophic Level: Producer
Makes its own food
Plants make food
2nd Trophic Level: Primary Consumer
Consumes producers
Mice eat plant seeds
3rd Trophic Level: Secondary Consumer
Consumes primary consumers
Snakes eat mice
4th Trophic Level: Tertiary Consumer
Consumes secondary consumers
Hawks eat snakes
Trophic Levels and Energy
Energy is passed up a food chain or web from lower to higher trophic levels. However, generally only about 10
percent of the energy at one level is available to the next level. This is represented by the energy
pyramid in Figure below. What happens to the other 90 percent of energy? It is used for metabolic processes or
given off to the environment as heat. This loss of energy explains why there are rarely more than four trophic
levels in a food chain or web. Sometimes there may be a fifth trophic level, but usually there’s not enough energy
left to support any additional levels.
Review
1. What is a trophic level?
Feeding positions in a food chain
2. What do energy pyramids represent?
Which organisms fall into which trophic level.
3. Explain how energy limits the number of
trophic levels in a food chain or web.
90% of energy is lost from level to level. At a
certain point, there will not be enough energy
therefore there cannot be another trophic level.
*adapted from: http://www.ck12.org/biology/Trophic-Levels/lesson/Trophic-Levels-BIO/
Symbiotic Relationships
Three Types of Symbiotic Relationships:
Mutualism
Definition:
When both organisms benefit
Commensalism
Definition:
When one organism benefits and
the other in unharmed or
unaffected.
Parasitism
Definition:
When one organism benefits and
the other is harmed.
Use the Scenarios below to figure out the Symbiotic Relationship:
1. The ants lay eggs on acacia tree so they get a nice safe place for their eggs. The acacia covers the
infected area with brown flesh (called a gall.) The plant has to use valuable resources to create the gall.
How are the ants affected? they have an area to lay their eggs and for their eggs to be protected
How is the acacia tree affected? must use valuable resources to create the gall
What is the Symbiotic Relationship? Parasitism
2. The remora attaches itself to the shark and saves energy since it doesn’t have to swim, and it gets to
snack on the sharks kills. The shark doesn’t get anything.
How are the remora affected? saves energy and doesn’t have to swim
How is the shark affected? it is unaffected
What is the Symbiotic Relationship? commensalism
3. This moray eel has a small fish cleaning between its teeth. The eel gets a clean mouth while the cleaner
fish gets a nice meal.
How is the moray eel affected? clean mouth
How is the fish affected? gets a nice meal
What is the Symbiotic Relationship? mutualism