Nutrition and Energy
Flow
I. How Organisms Obtain Energy
-Obtain means to get.
-The ultimate source of the energy for life on
earth is the sun.
-Energy is the ability to cause change.
I. How Organisms Obtain Energy
1.
Autotrophs: The producers.
Producers turn light energy from the sun into
food through a process called photosynthesis.
Ex: Trees, plants, algae.
I. How Organisms Obtain Energy
-Photosynthesis happens in the leaves of plants in special
organelles called chloroplasts.
-Chloroplasts contain a chemical called chlorophyll which
helps to capture the sun’s energy.
-Photosynthesis is the process of turning light energy into
sugar.
Equation for Photosynthesis:
6CO + 6H2O  C6H12O6 + 6O2
carbon + water  glucose + oxygen
dioxide
(sugar)
Questions
What provides energy for life on earth?
-the sun
What is energy?
-the ability to cause change
Is a producer and an autotroph the same thing?
-yes
What is an example of a producer?
-a plant
What is photosynthesis?
-photosynthesis is when a plant turns light energy into food.
Where does photosynthesis happen?
-in the leaves of plants in special organelles called chloroplasts.
I. How Organisms Obtain Energy
2.
Heterotrophs: The consumers.
A consumer can’t make it’s own food so it has
to eat other organisms.
Ex: Lions, Humans, Rabbits.
I. How Organisms Obtain Energy
Examples of heterotrophs:
1. Herbivore-eats only plants (autotrophs).
Ex: Rabbits
2. Carnivore-eats only animals (heterotrophs).
Ex: Lions
3. Omnivore-eats plants and animals.
Ex: Humans
4. Scavenger-eats dead animals and garbage.
Ex: Vultures
5. Decomposer-breaks down dead or dying material.
Ex: Bacteria, fungi
Questions
What is a consumer?
-an organism that cannot make its own food.
What is an example of a consumer?
-humans
Is a consumer the same thing as a heterotroph?
-yes
What kind of heterotroph is this?
-carnivore
What kind of heterotroph is this?
-decomposer
What kind of heterotroph is this?
-herbivore
What kind of heterotroph is this?
-scavenger
II. Flow of Matter and Energy in
Ecosystems
-Flow means to move.
-Matter flows from producer to consumer.
-Energy is transferred from one organism to the next
as matter cycles, however, a lot of energy is lost to
the environment as heat.
Autotrophs
Third-order
heterotrophs
First-order
heterotrophs
Second-order
heterotrophs
Decomposers
II. Flow of Matter and Energy
1. Food chain - a model that shows how
how matter and energy moves through an
ecosystem.
berries → mice → black bear
II. Flow of Matter and Energy
-Nutrients/energy move from producer to
consumer to decomposer.
Example food chain:
berriesrabbittiger
**The arrows in a food chain show the direction
of energy movement.
II. Flow of Matter and Energy
-Each organism in a food chain is a feeding step,
or trophic level in the movement of matter and
energy.
-Only 10% of energy is passed up each trophic
level!!!
-Because so much energy is lost at each trophic
level, there can only be 3-4 steps in a food chain.
II. Flow of Matter and Energy in
Ecosystems
2. Food Web-a model which shows all
possible feeding relationships at each trophic
level in a community.
***A food web is more realistic than a food
chain because organisms depend on more than
one other species for food.
Chihuahuan raven
Honey mesquite
(pods eaten by beetles)
Pronghorn
antelope
Example
Gambel
quail
Food Web
Jackrabbit
Long-tail
weasel
Desert
tortoise
Prickly
pear cactus
Coyote
(top carnivore)
Roadrunner
Kangaroo rat
(seed eater)
ants
Texas horned
lizard
Red spotted
toad
Mexican
whiptail lizard
Mojave
rattlesnake
Questions
What does flow mean?
-to move
Energy flows from _______ to _______ in an ecosystem.
-Energy flows from producer to consumer in an ecosystem.
What is a food chain?
-a model that shows how energy flows in an ecosystem.
What is a food web?
-a model which shows all the feeding relationships in an ecosystem.
Which is more realistic, a food web or a food chain?
-a food web is more realistic than a food chain b/c is shows all possible feeding relationships.
What is a trophic level?
-a feeding step.
How much energy can be passed up each trophic level?
-10%
Why can there only be 3-4 trophic levels?
-There can only be 3-4 trophic levels b/c only 10% of the energy is passed up each level, which means that after 3 or 4
levels, energy will run out.
II. Flow of Matter and Energy in
Ecosystems
3. Ecological Pyramids-a model which shows
how energy flows through an ecosystem.
Pyramid of Energy
-Pyramid of Energy-shows
how energy decreases at
each trophic level. Only
10% of the energy is passed
up each level!
Heat
Heat
0.1% Consumers
1% Consumers
10% Consu
Heat
Heat
100
Produ
-Pyramid of Biomassshows the weight at each
trophic level.
Pyramid of Numbers
Fox (1)
Birds (25)
Grasshoppers (250
Grasses (300
Pyramid of Biomass
1 kilogram of
human tissue
10 kilograms
of beef
100 kilograms
of grain
-Pyramid of Numbers shows the number of
organisms eaten by the
animal above it on the
pyramid.
Questions
What is the Pyramid of Energy?
-the Pyramid of Energy is an ecological pyramid which shows how much energy is in
each trophic level.
Does the amount of energy increase or decrease as you go up each trophic level?
-decrease
Why does the amount of energy decrease?
-energy is lost to the environment as heat.
What is the Pyramid of Numbers?
-the Pyramid of #’s is an ecological pyramid which shows how many organisms exist at
each trophic level.
What is the Pyramid of Biomass?
-the Pyramid of Biomass is an ecological pyramid which shows how much weight exists
at each trophic level.