PHOTOSYNTHESISHonors Biology, Arizona College Prep - Erie
Mrs. GlassmeyerTextbook 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. Flattened sacs containing photosynthetic pigments
Grana – pancake-like stacks of thylakoids
Stroma – Area between the thylakoids and grana
Thylakoid Stroma
Grana
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.
2. Light energy converted to
chemical energy. Using energy to
make ATP and NADPH
3. Uses chemical energy to form
organic compounds. ATP and
NADPH are used to power the
synthesis of carbohydrates from
CO2
Light-dependent
reactions
Light-independent
reactions
The Calvin cycle
6 CO2
carbon
dioxide
+ 12 H2O
water
+ Light energy C6H12O6
glucose
+ 6 O2
oxygen
+ 6 H2O
water
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. What is a pigment?
2. Why is it advantageous for a plant to have multiple
pigments?
3. 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.
0
10
20
30
40
50
60
70
80
90
Light Intensity
Rate
of
Ph
oto
syn
thesis
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
and ineffective, stomata begins to close limiting water loss
and CO2 entry into the leaves.
0
10
20
30
40
50
60
Temperature
Ra
te o
f
Ph
oto
sy
nth
es
is
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.
0
10
20
30
40
50
60
70
80
90
Light Intensity
Rate
of
Ph
oto
syn
thesis
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
Photosynthesis
Cellular
Respiration
Autotrophs &
HeterotrophsAutotrophs
Light
Sugars and oxygen
Carbon dioxide and water
Biochemical Pathway – series of reactions that are linked,
the products of one reaction are consumed in the next
reaction.
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 an autotroph?
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. Why is photosynthesis and cellular respiration
considered a biochemical pathway?
2. Why are plants green?
3. What part of photosynthesis makes sugars
(light reactions, electron transport chain or the
Calvin cycle)?
4. 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.