Energy Transfer and
Feeding Relationships
“WHAT’S FOR DINNER?”
Reminders and Take Notice!
 Your lab is due on Monday, March 25. You and
your partner will be marked on:



proper arrangement of the write up
completion of the lab in its entirety
Your ability to reflect upon the observations made based on
the experiment you carried out
 You will have your first quiz on Wed. March 27
 Topics include 1. The Earth’s Spheres, 2. Biotic and Abiotic
features, and 3. Energy Consumption + Feeding Relationships
 In other words, the first three slide shows, omitting adaptation
Feeding types
Animals can be grouped in several ways. One way of doing
this is based on how animals feed.
Some organisms are producers.
Producers make their own food.
Plants produce their own food using
light energy from the Sun. Some types
of bacteria can also make their own food
by using light or chemical reactions.
Consumers cannot make
their own food. They must
consume other organisms to
get the food that they need.
Where does all the Energy in a food chain
come from?
• Major source of energy for our planet
 Provides energy used by green plants to make their
own food in the process known as Photosynthesis
 Plants provide food for other organisms
 Also provides solar energy to generate electricity,
light energy and thermal energy to warm the planet
and its inhabitants
How does the Energy get IN to
the Food Chain?
Photosynthesis
 Executed by plants
 A process by which plants take in the sun’s energy, carbon
dioxide and water to produce oxygen and stored energy
upon which plants grow and survive
Carbon Dioxide + Water + Sunlight  Sugar (energy) + Oxygen
CO2 + H2O + Sunlight  C6H12O2 + O2
 The reason photosynthesis occurs in plants and not animals
is because it requires a chemical called chlorophyll
How do CONSUMERS USE this energy?
Cellular Respiration
 Occurs in animals
 A process by which animals take in sugar and
oxygen to fuel the body while producing water and
carbon dioxide
C6H12O2 + O2  CO2 + H2O + ATP
Complementary Processes
 The product of one process equals the starting
components of the other process
Types of Consumers
 Herbivores:
plant eaters (eg. Rabbit)
 Carnivores:
meat eaters (eg. Fox)
 Omnivores:
plant and meat eaters (eg. Bear)
Food chains – what eats what?
With the following groups, create a food chain, identifying
each group member as a plant or animal.
**REMEMBER WHAT YOU WERE AND WHERE YOU
FELL IN THE CHAIN.
Arctic 1
Caroline
Emma
Micaela
Tatum
Forest 1
Paul
Tristan
Jacob T.
Luke
Pond 1
Patrick
Tony
Stephen
Arctic 1
Nathan
Nick G.
Hennadiy
Nick R.
Forest 1
Matt
Kyle
Alex
Zach
Arctic 2
Jo-Anna
Holly
Julie
Katie
Forest 2
Karly
Jillian
Melissa
Sarah
Pond 2
Jim
Derek
Keegan
Arctic 2
David
Oliver
Madi
Liv
Forest 2
Alec
Jacob M.
Jacob R.
Jacob B.
Pond
Rachel
Tasha
Mandy
Cindy
Food chains
A food chain shows what is eaten by what.
Each arrow means ‘eaten by’.
leaf
caterpillar
bird
cat
What does this food chain show?
A leaf is eaten by a caterpillar, which is eaten by a bird,
which is eaten by a cat.
Energy is transferred from one organism to another in
the direction of the arrow
Food chains – activity
Green plant
Goat
Owl
Rabbit
Mouse
Wild Cat
Snake
Eagle
Lion
Jackal (like a wolf)
Ranking consumers
A food chain can be used to rank different types of consumers.
seaweed
producer
limpet
primary
consumer
crayfish
human
secondary
consumer
tertiary
consumer
 producers – make their own food;
 primary consumers – eat producers;
 secondary consumers – eat primary consumers;
 tertiary consumers – eat secondary consumers.
Do animals only eat one species??
 Food chains show simple relationships
 Food webs show all the feeding relationships in a
habitat
Which of these organisms are producers?
Which ones are Herbivores?
Which ones are carnivores?
Which ones are omnivores?
Build a food web
Nuts Mice Wolf Bear
Nuts Deer Wolf Bear
Bark Rabbit Wolf Bear
Blossoms Insects Birds Red fox Bear
Blossoms Bees Bear
Bark Rabbit Red fox Bear
Food Pyramids
 We draw food webs to show how animals’ eating
habits are related
 We draw pyramids to show how energy (biomass)
is passed along from one animal to the next
 What shape is a pyramid?
 What can the shape tell us about energy at the top?
What is Biomass?
The total dry mass
of living organisms
in a group or area
Example:
How do we measure the biomass for field of
grass? (producer level on our food chain)
Dry the grass then take the mass of it
= biomass of the grass
Biomass tells us how much Energy is available
to the next trophic level
 Why do we take the water out when we
measure biomass???
 Example: What has more energy?
Watermelon
Bread
Two Types of Pyramids
1) Pyramid of Numbers
 Count number of each organism
 Not as accurate
 Example: 1 oak tree, 10 caterpillars, 2 birds
Blackbird
Caterpillar
Oak Tree
Types of Pyramids
2) Pyramid of Biomass
 Weigh all the organisms at each stage of the food
chain (biomass of producers > consumers)
 More accurate to show feeding relationship
Example: even if there is only one oak tree it can have
many caterpillars living from it
Blackbird
Caterpillars
Oak Tree
Food Pyramids and Energy
Only about 10%
of the energy
from one level
gets passed to
the next
Reasons why biomass decreases as you go up the
pyramid:
 Not all of the plant is eaten by herbivores
(only eat leaves, not roots)
 Not everything eaten is digested (wolf eats a deer,
uses meat but fur is waste)
 Energy is lost in the form of body heat, used for
activity, to carry out life processes
Example:
When we eat chicken for dinner we do not get
100% of the energy from it. Why?
 Eating lower on the food chain wastes less
energy
 Animals need energy to live, grow and reproduce
 Animals get less energy from what they eat if at the
top of the food chain
 This can explain why there are usually fewer
carnivores than herbivores, and fewer herbivores
than plants
Eagle
Rabbit
Grass
Practice Calculation for Energy Transfer
Calculate the units of energy in each trophic level of the
food chain below. Remember that only 10% of the
energy gets passed along.
(Starting energy units) x (0.10) = Energy passed
along
(Starting energy units) x (0.10) = Energy passed
along
(2543) x (0.1) = 254.3 units of energy (grasshoppers)
(254.3) x (0.1) = 25.43 units of energy (spotted
frog)
TRY THE NEXT STEP ON YOUR OWN!
(Starting energy units) x (0.10) = Energy passed
along
(25.43) X (0.1) = 2.543 units of energy (redtailed hawk)
Answer:
 Hint: Every trophic level you move up in the food
chain, you move the decimal over one place to the left
(This is 10% of the starting number)
254.3 energy
units
25.43 energy
units
2.543 energy
units