Photosynthesis and Cellular
Respiration
6 TH SCIENCE
MR. REYNOLDS
What is PHOTOSYNTHESIS?
 With your new lab partner, come up with your own
definition of photosynthesis. You have three
minutes, GO!!!!
PHOTOSYNTHESIS……
 Who would like to share their definition?
 What is photosynthesis?
 The process by which a cell captures energy in
sunlight and uses it to make food.
 Does photosynthesis affect all living things?
 Yes, nearly all living things obtain energy either
directly or indirectly from the energy of sunlight
captured during photosynthesis.
The sun is
the source
of energy
for most
living
things
Diagram of Photosynthesis…
Plants such as
grass use energy
from the sun to
make their own
food
The wildebeest
obtains energy by
eating grass
The tiger obtains
energy by feeding
on the wildebeest
Autotroph and Heterotroph
 What is a autotroph?
 An organism that makes its own food through the




process of photosynthesis.
Plants are AUTOTROPHS
What is a heterotroph?
An organism that cannot make its own food.
Animals, like humans, are heterotrophs!
Stages of Photosynthesis
 What happens during photosynthesis?
 Plants and some other organisms use energy from




the sun to convert carbon dioxide and water into
oxygen and sugars.
Stage 1:
Involves capturing the energy in sunlight.
Where does stage 1 take place?
In the leaves of plants, CHLOROPLASTS capture
the energy in sunlight.
Stages of Photosynthesis
 What are pigments?
 Colored chemical compounds that absorb light.
 What is the main pigment found in chloroplasts?
 Chlorophyll
 Stage 2:
 The cell uses the captured energy to produce sugars.
 What two raw materials are needed in Stage 2?
 Water (H2O) and Carbon Dioxide (CO2)
 Where does CO2 enter the plant?
 Small openings on the undersides of leaves called
stomata.
Diagram of the Stages of Photosynthesis…
Sun
Stage 1:
Chloroplasts
in plant cells
capture
energy from
sunlight
Carbon
dioxide (CO2)
enters the leaf
through the
stomata
Stage 2: The
captured light
energy is used to
produce sugars
and oxygen from
water and carbon
dioxide
Water enters
the plant
through roots
and moves
upward to
the leaf
Sugars produced
are used by the
plant cells for
energy
Oxygen
exits
through
the
stomata
The Photosynthesis Equation…
raw
materials
products
Light
Energy
 6 CO2 + 6 H2O
carbon
dioxide
water
C6H12O6 + 6 O2
a sugar
oxygen
What is Respiration?
 With your new lab partner, come up with your own
definition of respiration. You have three minutes,
GO!!!!
What is Respiration?
 Who would like to share their definition?
 What is respiration?
 The process by which cells obtain energy from
glucose (sugar).
 What occurs during respiration?
 Cells break down simple food molecules such as
sugar and release the energy they contain.
 BOTH plant and animal cells perform respiration!
The Stages of Respiration…
 Where does Stage 1 take place and what occurs?
 In the cytoplasm. Molecules of glucose are broken
down into smaller molecules. Oxygen is NOT
involved in stage 1.
 Where does Stage 2 take place and what occurs?
 In the mitochondria. The small molecules of glucose
are broken down into even smaller molecules.
Oxygen IS required and a great deal of energy is
released.
Diagram of Respiration…
Stage 2:In the
mitochondria, the
smaller molecules
combine with oxygen to
produce water and
carbon dioxide. This
reaction releases a large
amount of energy.
Stage 1:In the
cytoplasm, glucose is
broken down into
smaller molecules.
A small amount of
energy is released.
H2O
glucose
Smaller
molecules
Smaller
molecules
mitochondria
energy
cytoplasm
O2
energy
CO2
Respiration Equation…
products
raw
materials
Light
Energy
 C6H12O6 + 6 O2
a sugar
oxygen
6 CO2 +6 H2O+energy
carbon
dioxide
water