Energy Flow in
Ecosystems

Section One
Energy Roles

 An organisms role is determined by how it obtains
energy and how it interacts with other organisms.
 What are the three energy roles an organism may
have:
 Producer
 Consumer
 Decomposer
Producers

 It is important to remember that energy enters an
ecosystems as sunlight
 Plants use the light in photosynthesis to turn water
and carbon dioxide into food molecules
 An organism that can make its own food is a
producer

 Producers are the source of all the food in the
ecosystem.
Consumers

 An organism that obtains its food by feeding on
other organisms is called a consumer
 Consumers are classified by what they eat:
 Herbivores-only eats plants
 Carnivores- only eats animals
 Omnivores –eats both plants and animals
 What are some examples?
Consumer

Carnivore
Herbivore
Omnivore
Decomposers

 Decomposers break down wastes and dead
organisms and return the raw materials to the
ecosystems.
 What are some examples of decomposers?
 What would happen if there were none?
Food chain and food
webs

 Energy enters most ecosystems as sunlight
 The energy is transferred to each organism that eats
a producer.
 The movement of energy through an ecosystem can
be shown in diagrams called food chains and food
webs
Food Chains

 A food chain is a series of events in which one
organism eats another and obtains energy.
 Remember that the first organism in the food chain is
always going to be a producer
 The second organism feeds on the producer is called
1st level consumer ‘
 The organism that feeds on the 1st level consumer is
called the 2nd level consumer
Food chain

Producer
1st level
2nd level
Consumer
Consumer
Food webs

 A food web consists of many overlapping food
chains
 An organism may play more than one role in the
ecosystem.
 Example:
 An omnivore like a mouse is a 1st level consumer
when it eats grass
 When the mouse eats a grasshopper it is a secondlevel consumer
Food webs

 Just as food chains overlap and connect, food webs
interconnect as well
 All the world’s food webs interconnect in what can
be thought of as a global food web.
Food Webs

Energy pyramids

 When an organisms eats, it obtains energy.
 The organism is going to use this energy to carry out
its daily functions such as moving growing, and
reproducing
 Since the animals use energy, it means that only a
portion of the energy it obtains will be available to
the next organism
Energy Pyramids

 A diagram called an energy pyramid shows the
amount of energy that moves from one feeding level
to another
 The most energy is available at the producer level
of the pyramid. As you move up the pyramid, each
level has less energy available than the level below.
Energy Pyramids

 In general only about 10% of the energy is passed on
to the next higher level.
 The organisms at higher higher levels of an energy
pyramid do not require less energy than animals on
the lower levels.
 Since so much energy is lost, it limits the number of
consumers an ecosystem can hold.
Energy pyramids

Photosynthesis

Section Two
Photosynthesis

 Every living thing needs energy in order to survive.
 Cells use energy to:
 Carry out their functions
 Make proteins
 Transport substances in and out of the cell
 Most organisms get their energy from the food that
they eat. However, plants are different they lack the
ability to graze or hunt so they obtain their energy in
a different way.
Photosynthesis

They Make It Using……. !!
Sources of Energy

 The process by which a
cell captures energy in
sunlight and uses it to
make food is called
photosynthesis
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Sources of Energy

 Nearly all living things
obtain energy either
directly or indirectly
from the energy of
sunlight captured
photosynthesis
Sources of Energy

 Plants manufacture
their own food through
the process of
photosynthesis.
 An organism that
makes it own food is
called an autotroph
Sources of Energy

 An organism that
cannot make its own
food is called a
heterotroph.
 Heterotrophs survive
by eating other
organisms or absorbing
them.
Cell Energy:
• Cells usable source of energy is called ATP

• ATP stands for adenosine triphosphate
Adenine
Ribose
3 Phosphate groups
• ADP stands for adenosine diphosphate

Adenine
Ribose
2 Phosphate groups
• All energy is stored in the bonds of compounds—
breaking the bond releases the energy

• When the cell has energy available it can store this
energy by adding a phosphate group to ADP, producing
ATP
• ATP is converted into ADP by breaking the bond between
the second and third phosphate groups and releasing
energy for cellular processes.

The Two Stages of
Photosynthesis

 During photosynthesis plants and some other
organisms use energy from the sun and to convert
carbon dioxide and water into oxygen and sugars.
 Occurs in two stages:
 Stage One: Capturing the Sun’s Energy
 Stage Two: Using Energy to Make Food
The Two Stages of
Photosynthesis

Stage One: Capturing
the Sun’s Energy

 The first stage of
photosynthesis
involves capturing the
energy in sunlight.
 This energy-capturing
process occurs mostly
in the leaves.
 The chloroplast are
green organelles inside
plant compounds that
absorb light.
Stage One: Capturing
the Sun’s Energy

 The green color comes from pigments, colored
chemical compounds that absorb light.
 The main photosynthetic pigment in chloroplast is
chlorophyll
Stage One: Capturing
the Sun’s Energy

 Chlorophyll has a
similar function as solar
panels. They capture
the sun energy, and use
the energy to carry out
its functions.
 Chlorophyll captures
light energy and uses it
to power the second
stage of photosynthesis.
Stage Two: Using
Energy to Make Food

 In the second stage, the cell uses the captured energy to
produce sugars.
 The cell needs two materials to make this work:
 Water
 Carbon dioxide
 Water enters the plant through the roots and the carbon
dioxide enters the plant through small openings on the
underside of the leaves called stomata
Stage Two: Using
Energy to Make Food

 Inside the chloroplasts,
the water and carbon
dioxide undergo a
series of complex
chemical reactions.
 The reactions are
powered by the energy
captured in the first
phase.
Stage Two: Using
Energy to Make Food

 Stage Two produces two products:
 Sugar
 Oxygen
 Recall that the sugar is a type of carbohydrate and
the cells use energy in the sugar to carry out
important cell function.
Stage Two: Using
Energy to Make Food

 The other product of
photosynthesis is
oxygen, which exits the
leaf through the
stomata.
 Almost all oxygen in
the Earth’s atmosphere
was produced through
the process of
photosynthesis
The Photosynthesis
Equation

 The events of photosynthesis can by summed up by
the following equation:
The Photosynthesis
Equation

 How photosynthesis is used:
1. Plants use some of the sugar for food.
2. The plant breaks down the sugar molecule to release
the energy they contain.
3. The energy is then used to carry out the cells
functions.
4. Used in the cell wall as cellulose
5. Stored for later use
The Photosynthesis
Equation

 When you eat food from plant, such as potatoes or
carrots, you are eating the plant’s stored energy.
Respiration

Section Three
How Food Gets to Your
Cells

1. Before your body can provide your body with energy, it
must pass through your digestive system.
2. In your digestive system your food is broken into small
molecules.
3. Molecules go from your digestive system through the
bloodstream to your body cells.
4. Inside the cells, the energy in the molecules is released
What is Cellular
Respiration?

 Cellular Respiration is the process by which cells
obtain energy from glucose.
 During cellular respiration, cells break down
simple food molecules such as sugar and release
the energy they contain.
 Cells of all living things carry out cellular respiration
continuously.
Types of Cellular
Respiration

There are two types of cellular respiration:
 Aerobic –requires oxygen
 Anaerobic – does not require oxygen
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Storing and Releasing
Energy

 During photosynthesis, plants capture and the
energy from sunlight and “save” it in the form of
carbohydrates, including sugars and starches.
 When cells need energy they “withdraw” it by
breaking down the carbohydrates in the process of
cellular respiration.
The Two Stages of Cellular
Respiration-Aerobic

 Like photosynthesis, respiration is a two-stage
process.
 Stage one also known as glycolosis, takes place in
the cytoplasm of the organism’s cells
The Two Stages of Cellular
Respiration-Aerobic

 There, molecules of glucose are broken down into
smaller molecules.
 In this stage oxygen is not involved and only a small
amount of energy is released
The Two Stages of Cellular
Respiration-Aerobic

 Stage Two also known as oxidization, takes place in
the mitochondria.
 Small food particles are broken down more
 The chemical reactions require oxygen, and they
release a lot of energy.
 This is way they call the mitochondria the “power
house” of the cell
The Two Stages of Cellular
Respiration-Aerobic

The Two Stages of Cellular
Respiration-Aerobic

 Products of respiration:
 Energy is release in both glycolysis(stage 1) and
oxidation (stage 2).
 Carbon dioxide
 Water
 These products are going to be diffused through the
cell membrane
The Two Stages of Cellular
Respiration-Aerobic

The Respiration
Equation

 Although respiration occurs in a series of complex
steps, the overall process can be summarized in the
following equation:
The Respiration
Equation

 How organisms get the raw materials for respiration:
 Plants undergo photosynthesis to make their own
sugar
 Animals get their sugar from consuming food
 The oxygen used in respiration comes from the air or
the water surrounding the organism
Photosynthesis vs.
Respiration

Photosynthesis
Respiration
 Chemical formula is
opposite respiration
 Chemical formula is
opposite photosynthesis
 Turn carbon dioxide and
water into sugar and oxygen
 Turn sugar and oxygen into
carbon dioxide and water
Photosynthesis vs.
Respiration

 Photosynthesis and
respiration keep the
levels of oxygen and
carbon dioxide fairly
consistent in Earth’s
atmosphere.
Fermentation

 Some cells are able to obtain energy from food
without using oxygen ----anaerobic respiration
 Organisms who do this:
 Single celled organisms who live in places that contain
no oxygen
 Mud
 Deep ocean
Fermentation

 Organisms who obtain their energy through
fermentation, an energy-releasing process that does
not require oxygen.
 The amount of energy released during fermentation,
however, is much lower than the amount released
during respiration.
Types of Fermentation

 Two Examples of Fermentation:
 Alcoholic fermentation
 Lactic acid fermentation
Alcoholic Fermentation

 One type of fermentation occurs when yeast and
some other singled-celled organisms break down
sugars.
 This is sometimes called alcoholic fermentation
because this is one product that is produced.
 The products of alcoholic fermentation are carbon
dioxide and a small amount of energy.
Alcoholic Fermentation

Alcoholic Fermentation

 CO2 in bread caused by
yeast causes it to rise.
 CO2 is the source of
bubbles in beer
Lactic Acid Fermentation

 Lactic Acid Fermentation occurs when your cells use
up oxygen faster than it can be replaced. Because
your cells lack oxygen, fermentation occurs.
Lactic Acid Fermentation

 The fermentation supplied your cells with energy
 One product of this type of fermentation is an acid
called lactic acid.
 When lactic acid builds up you feel pain in your
muscles