PHOTOSYNTHESIS
Honors Biology, Arizona College Prep - Erie
Mrs. Glassmeyer
Textbook Reference: 6.1-6.2, The Living World 7th edition
Learning Goals
Unit Learning Goal: You can compare/contrast all components of
photosynthesis & cellular respiration in terms of energy, organic and
inorganic molecules as well as accurately diagram all the processes as
part of the flow of energy and matter through all levels of organization
in an ecosystem.
Presentation Learning Goal(s):
1.
You can identify organic & inorganic molecules of the process of
photosynthesis and write out the equation using proper chemical
notation.
2.
You can compare the light dependent and light independent
reactions of photosynthesis using scientific vocabulary.
3.
You can link pigments and the structure of the chloroplast to the
process of photosynthesis.
4.
You can describe the process of photosynthesis as a part of the
biochemical pathway that facilitates the flow of energy and matter
through all levels of organization in an ecosystem.
Reflection Time: Learning Goal Scale
4 - You can compare/contrast all components of photosynthesis &
cellular respiration in terms of energy, organic and inorganic molecules
as well as accurately diagram all the processes as part of the flow of
energy and matter through all levels of organization in an ecosystem.
3 - You can compare/contrast some components of photosynthesis &
cellular respiration in terms of energy, organic and inorganic molecules
as well as diagram most of the processes as part of the flow of energy
and matter through all levels of organization in an ecosystem.
2 - You can explain some of the learning goal on your own but may
need some help to complete the entire learning goal.
1 - You can answer questions about the learning goal but cannot give
specifics using your own words.
Fig. 6.1 Journey into a leaf
Fig. 6.1 Journey into a leaf
What is photosynthesis?
Photosynthesis is the process by which cells harvest light energy and
convert it to chemical energy stored in the chemical bonds of sugars
(glucose).
• Glucose is a monosaccharide used to power the process of cellular
respiration, which produces the Adenosine Triphosphate (ATP) that cells
use as their dominant source of energy.
Where does it take place?
Plasma membranes of some bacteria
Cells of algae
Leaves of plants
NOW…
What is the equation for Photosynthesis? Knowing what we know, let’s see
if we can figure it out and balance it. BUT…Before we start…A brief
Chemical Equation Review…
Review: Chemical Reactions
An example…
A chemical equation has a specific structure. Those
molecules considered reactants are on the left side of the
equation. Those molecules considered products are on
the right side of the equation. An arrow is used to indicate
that the reactants react together to form or yield the
products.
Were we right?
6CO2 + 6H20 + light energy
C6H12O6 + 6O2
Reactants
• 6 molecules of Carbon dioxide
• 6 molecules of Water
• light energy
Products
• 1 molecule Glucose (which is a monosaccharide)
• 6 molecules of Oxygen
What is the structure of the chloroplast?
Thylakoid- structural
unit of photosynthesis. Grana
Flattened sacs
containing
photosynthetic pigments
Grana – pancake-like
stacks of thylakoids
Stroma – Area between
the thylakoids and
grana
Thylakoid
Stroma
How does the water and CO2 get into the plant?
• Xylem
• A structure in the stem of a plant that moves water from the roots to
the leaves.
• Stomata
• Openings on the leaf that allow gases to move in and out.
• Surrounded by guard cells that can open and close as necessary.
What are the stages of Photosynthesis?
1. Capturing energy from
sunlight. Produces oxygen.
Light-dependent
2. Light energy converted to
reactions
chemical energy. Using energy to
make ATP and NADPH
Light-independent
3. Uses chemical energy to form
reactions
organic compounds. ATP and
The Calvin cycle
NADPH are used to power the
synthesis of carbohydrates from
CO2
6 CO2 + 12 H2O + Light energy
C6H12O6 + 6 H2O + 6 O2
carbon
dioxide
water
glucose
water
oxygen
Where do the stages take place?
Significance of Light Reaction
In Photosystem II:
• Oxygen is produced from the breakdown of water
• During electron transport, H+ ions accumulate inside
thylakoid – this drives ATP production (Chemiosmosis)
In Photosystem I:
• Electrons combine with a proton to make the energy
carrier NADPH.
Light Independent Reaction (Calvin Cycle)
• Here CO2 is converted into carbohydrates
• Light independent (doesn’t need light)
• Can happen in the day or night
• Occurs in the stroma of the chloroplast
What Pigments are in the Chloroplast?
Pigments – compounds that absorb light energy
Significant pigments involved in photosynthesis
• Chlorophyll a
• Only chlorophyll a is directly involved in light reaction of
photosynthesis
• Chlorophyll b
• helps to capture light energy
• accessory pigment – helps organism capture more energy
• Carotenoids
• accessory pigment – helps organism capture more energy
• Produce – yellow, orange, red, brown colors
• Mostly seen in flowers and fruits
• Also seen during fall when chlorophyll breaks down
Colors of Visible Light
Absorption Spectrum of pigments
Check Yourself!
1.
2.
3.
What is a pigment?
Why is it advantageous for a plant to have multiple
pigments?
What would you prefer to wear in the summer- a black
t-shirt or a white t-shirt (if you had to pick one) and
Why?
What factors affect the rate of photosynthesis?
• Affected by plant’s environment
• Light intensity-
• as light  , photosynthesis  until light
saturation point.
• Carbon Dioxide
CO2 , photosynthesis 
• Temperature
• Chemical reactions general  with temperature
• If it gets to hot the enzymes can denature and
the reaction 
What 3 Factors Affect the Rate of
Photosynthesis?
Photosynthesis and plant environment includes:
 Light intensity – more light intensity, more electrons in
the chlorophyll molecules of both photosystems to
become excited.
 CO2’s influence, increased levels of CO2 stimulate
photosynthesis until a plateau is reached.
Rate of Photosynthesis
90
80
70
60
50
40
30
20
10
0
Light Intensity
What 3 Factors Affect the Rate of
Photosynthesis?
 Temperature – raising temperature accelerates
the chemical reaction, but it peaks at a certain
temperature.
 The enzymes that catalyze the reactions become unstable
Rate of
Photosynthesis
and ineffective, stomata begins to close limiting water loss
and CO2 entry into the leaves.
60
50
40
30
20
10
0
Temperature
What 3 Factors Affect the Rate of
Photosynthesis?
Photosynthesis and plant environment includes:
 Light intensity – more light intensity, more electrons in
the chlorophyll molecules of both photosystems to
become excited.
 CO2’s influence, increased levels of CO2 stimulate
photosynthesis until a plateau is reached.
Rate of Photosynthesis
90
80
70
60
50
40
30
20
10
0
Light Intensity
Review: Link to ecosystems
• Autotrophs- an organism that uses energy to
synthesize organic molecules (sugar) from
inorganic substances (ex. Light)
• Can make its own food
• Includes-plants, some bacteria, and algae
• Heterotrophs – must obtain energy from source
other than self
• Includes animals (humans), fungi, some protista
The ecological Biochemical pathway
Light
Photosynthesis
Sugars and oxygen
Autotrophs &
Heterotrophs
Autotrophs
Carbon dioxide and water
Cellular
Respiration
Biochemical Pathway – series of reactions that are linked,
the products of one reaction are consumed in the next
reaction.
What is an autotroph?
 Autotroph – an organism that uses energy to
synthesize organic molecules from inorganic
substances.
• Organisms that obtain their energy by making their
own food, like plants.
• Some autotrophs convert water (H20 + CO2) & carbon
dioxide from the environment into energy rich
substances such as sugars and starches
• Examples: Sugars, starches
What Is a Heterotroph?
• An organism that obtains organic food molecules by
eating other organisms or their by-products.
• Organisms that must take in food to meet their
energy needs.
• Examples include: all animals and fungi.
•Also many unicellular organisms.
•A few plant species.
Special Adaptations
• Most plants are C3 plants
• C4 plants
• Found in hot dry weather
• They have stomata closed during the hottest part of the
day to save up CO2 and water
• Corn, sugar cane, and crabgrass
• CAM
• Also found in hot day climates
• Keep stoma open and night and closed during the day to
save extreme amounts of water
• Cactus and pineapple
Check Yourself Again!
1.
2.
3.
4.
Why is photosynthesis and cellular respiration
considered a biochemical pathway?
Why are plants green?
What part of photosynthesis makes sugars
(light reactions, electron transport chain or the
Calvin cycle)?
What is required from the light reactions in
order to fuel the Calvin cycle?
Reflection Time: Learning Goals
Presentation Learning Goal(s):
1. You can identify organic & inorganic molecules of the
process of photosynthesis and write out the equation using
proper chemical notation.
2. You can compare the light dependent and light independent
reactions of photosynthesis using scientific vocabulary.
3. You can link pigments and the structure of the chloroplast to
the process of photosynthesis.
4. You can describe the process of photosynthesis as a part of
the biochemical pathway that facilitates the flow of energy
and matter through all levels of organization in an
ecosystem.
Ticket Out the Door: Rate yourself on one of the learning goals
and summarize what you know. Make sure to write out the
number of the learning goal.
Reflection Time: Unit LG Scale
4 - You can compare/contrast all components of photosynthesis &
cellular respiration in terms of energy, organic and inorganic molecules
as well as accurately diagram all the processes as part of the flow of
energy and matter through all levels of organization in an ecosystem.
3 - You can compare/contrast some components of photosynthesis &
cellular respiration in terms of energy, organic and inorganic molecules
as well as diagram most of the processes as part of the flow of energy
and matter through all levels of organization in an ecosystem.
2 - You can explain some of the learning goal on your own but may
need some help to complete the entire learning goal.
1 - You can answer questions about the learning goal but cannot give
specifics using your own words.