Comparing Photosynthesis
and Respiration
The most important chemical
reaction in the world is…
PHOTOSYNTHESIS
The chemical reaction
for photosynthesis is
6CO2 + 6H2O + energy
C6H12O6 + 6O2
Comparing Photosynthesis
and Respiration
PHOTOSYNTHESIS
Carbon Dioxide
6CO2 + 6H2O + energy
Water
Sunlight
Sugar
C6H12O6 + 6O2
Oxygen
Comparing Photosynthesis
and Respiration
PHOTOSYNTHESIS
Stage 1
Chlorophyll in the
Chloroplasts
captures sunlight
Comparing Photosynthesis
and Respiration
PHOTOSYNTHESIS
Stage 2
The cell uses the
captured sunlight,
carbon dioxide
and water to
make food
Comparing Photosynthesis
and Respiration
PHOTOSYNTHESIS
Stage 2
Carbon Dioxide
enters the plant
through Stomata
-small openings
on the underside
of the leaf
COMPARING PHOTOSYNTHESIS AND RESPIRATION
THE PHOTOSYNTHESIS - RESPIRATION CYCLE
PHOTOSYNTHESIS
Plants Produce Sugar
RESPIRATION
Organisms Use
Oxygen
Carbon Dioxide
Plants use
Water
Energy
Organisms Produce
Comparing Photosynthesis
and Respiration
The process by which cells obtain
energy from glucose
RESPIRATION
The chemical reaction
for respiration is
C6H12O6 + 6O2
6CO2 + 6H2O + energy
Comparing Photosynthesis
and Respiration
RESPIRATION
Oxygen
C6H12O6 + 6O2
Sugar
Carbon Dioxide
6CO2 + 6H2O + energy
Water
Comparing Photosynthesis
and Respiration
RESPIRATION
Stage 1
Takes place in the
cytoplasm
Molecules of glucose are
broken down into
smaller molecules
Oxygen is NOT
involved
Small amount
of energy is
released
Comparing Photosynthesis
and Respiration
RESPIRATION
Stage 2
Takes place in the
Mitochondria
Small molecules are
broken down into even
smaller molecules
A great deal of
energy is
released
Oxygen is
required
Carbon dioxide
and water are
also produced
COMPARING PHOTOSYNTHESIS AND RESPIRATION
THE PHOTOSYNTHESIS - RESPIRATION CYCLE
PHOTOSYNTHESIS
Plants Produce Sugar
Oxygen
RESPIRATION
Organisms Use Sugar
Oxygen
Carbon Dioxide
Plants use
Organisms Produce
Water
Carbon Dioxide
Energy
Water
Energy
COMPARING PHOTOSYNTHESIS AND RESPIRATION
THE PHOTOSYNTHESIS - RESPIRATION CYCLE
PHOTOSYNTHESIS
Plants Produce Sugar
Oxygen
Carbon Dioxide
Plants use
Water
Energy
Comparing Photosynthesis
and Respiration
Testing Photosynthetic Rate of Elodea
Elodea – a common water plant
Elodea releases bubbles of oxygen as it
photosynthesizes
Freshly cut Elodea stems produce more
bubbles than the leaves
Comparing Photosynthesis
and Respiration
Testing Photosynthetic Rate of Elodea
Materials
Scissors
Elodea Plants
Large Container
Clear test tube
Sunlight
Water
Comparing Photosynthesis
and Respiration
Testing Photosynthetic Rate of Elodea
Procedures
Fill the large container
half full of water
Cut the stem of the Elodea plant at
an angle (for greater surface area)
Comparing Photosynthesis
and Respiration
Testing Photosynthetic Rate of Elodea
Procedures
Insert the plant, cut stem first,
into the test tube
Fill the test tube to overflowing with
water
Comparing Photosynthesis
and Respiration
Testing Photosynthetic Rate of Elodea
Procedures
Cover the top of the test tube
with your thumb
Invert the test tube over the beaker
and put the test tube with your
thumb still covering the opening into
the beaker
Comparing Photosynthesis
and Respiration
Testing Photosynthetic Rate of Elodea
Procedures
Release your thumb and gently
settle the test tube on the
bottom of the container
Place the beaker and test tube in
sunlight or under a bright lamp
Comparing Photosynthesis
and Respiration
Testing Photosynthetic Rate of Elodea
Procedures
At 5 minute intervals for a total
of 15 minutes, record the
number of bubbles produced
Make a graph of your findings
Have someone in your group report out
to the class
COMPARING PHOTOSYNTHESIS AND RESPIRATION
THE PHOTOSYNTHESIS - RESPIRATION CYCLE
RESPIRATION
Organisms Use Sugar
Oxygen
Organisms Produce
Carbon Dioxide
Water
Energy
Comparing Photosynthesis
and Respiration
Respiration and Carbon Dioxide
Bromthymol Blue (BTB)
An acid-base indicator that can be used
to measure levels of carbon dioxide (CO2)
BTB changes color from blue to green
and then yellow as it gets more acidic
Comparing Photosynthesis
and Respiration
Respiration and Carbon Dioxide
Bromthymol Blue (BTB)
If carbon dioxide is added to the solution
it will become more acidic and change
color moving to green and then yellow
If carbon dioxide is removed from the
solution it will become more basic and
change color moving to blue
Comparing Photosynthesis
and Respiration
Respiration and Carbon Dioxide
This experiment uses
Bromthymol Blue to
examine the
relationship between
exercise and the
amount of carbon
dioxide you produce
Comparing Photosynthesis
and Respiration
Respiration and Carbon Dioxide
Materials
2 plastic cups
2 straws
Bromthymol
Blue solution
Paper towels
Timer
Comparing Photosynthesis
and Respiration
Respiration and Carbon Dioxide
Procedure
Label one cup “1” and the
other cup “2”
Fill both cups to the marked line
with BTB
Comparing Photosynthesis
and Respiration
Respiration and Carbon Dioxide
Procedure
Record the color in both
cups on your lab sheet
Place a straw in cup 1
Comparing Photosynthesis
and Respiration
Respiration and Carbon Dioxide
Procedure
Have a group member blow
through the straw into the
solution until it changes color
Have a group member time how
long it takes for the solution to
change color
Comparing Photosynthesis
and Respiration
Respiration and Carbon Dioxide
Procedure
Record how long it took for the
solution to change color on your
lab sheet
Remember the solution is
changing color because you are
exhaling carbon dioxide into it
Comparing Photosynthesis
and Respiration
Respiration and Carbon Dioxide
Procedure
Predict how long it would take
the solution to change color
after exercise
Record your prediction on
your lab sheet
Comparing Photosynthesis
and Respiration
Respiration and Carbon Dioxide
Procedure
Design an experiment to test
your prediction
This means a group member
must do some form of
exercise (like jumping jacks)
Comparing Photosynthesis
and Respiration
Respiration and Carbon Dioxide
Procedure
The exercise should be
something you can do “in place”
near your tables
Only one group member will
perform the exercise
Comparing Photosynthesis
and Respiration
Respiration and Carbon Dioxide
Procedure
Write down the steps of your
experiment
Get your teacher’s approval BEFORE
you begin your experiment
Comparing Photosynthesis
and Respiration
Respiration and Carbon Dioxide
Procedure
Follow the directions in the
Analyze and Conclude section of
your lab sheet to conduct your
experiment and record your
results