Chapter 8
Photosynthesis
Ch. 8-1 Energy & Life
• All living things need energy
• Plants capture energy from
sunlight to produce food (autotrophs)
• Animals get energy from food
(heterotrophs)
Chemical Energy
• One of the most imp. compounds that
living things use to store energy – ATP
• ATP – adenosine triphosphate
• Has 3 parts: →
• When the bond
is broken b/t the
2nd & 3rd phosphate
energy is released
ATP – ADP cycle
• When ATP gives up some energy, it’s converted
to ADP (adenosine diphosphate)
• ADP doesn’t
have much
energy, so
it must be
re-converted
to ATP again
Ch. 8-2 Investigating
Photosynthesis
• Van Helmont – discovered that plants gain most
of their mass from water
Investigating Photo
•
•
Priestly – discovered oxygen
←his expt.
Ingenhousz – showed that
plants give off O2 only
when exposed to light
•
Equation for Photosynthesis
• 6 CO2 + 6 H2O → C6 H12 O6 + 6 O2
• carbon dioxide + water → glucose + oxygen
Light & Photo
• Plants gather sunlight with light-absorbing
molecules called pigments *necessary for
photosynthesis!
• Main pigment is chlorophyll
• Chlorophyll absorbs light only in certain parts of
the visible spectrum
• Two types of Chlorophyll:
• Chlorophyll a - absorbs blue-violet and red light.
• Chlorophyll b
•
- absorbs blue and red light.
Green light is not absorbed! It’s reflected!
Light & Photo
• Plants do not
absorb light
well in the
green part of
the spectrum.
Why?
(green light
is reflected by
plants, which is
why they appear green)
• A pigment will be the color of the spectrum of light that it
CANNOT absorb!
http://www.sciencelearn.org.nz/ScienceStories/Harnessing-the-Sun/Sci-Media/Animations-and-
Accessory Pigments:
Their purpose is to absorb light where chlorophyll
does not – they absorb green light! (They
complete the absorption spectrum)
• Carotenoids: which produce orange, red, and
brown colors in such things as carrots,
cranberries, grapes, and rutabagas
• Anthocyanins: produce purple, blue and red
colors, such as: concord grapes, blueberries,
and plums.
• Xanthophylls: produce yellow colors, such as in
corn and daffodils
stoma
Ch. 8-3 The Reactions of Photo
• Take place in the chloroplasts
• Parts of a chloroplast:
thylakoids: saclike photosynthetic
membranes
granum(a) – stacks
of thylakoids
stroma – space
outside thylakoid
http://www.mhhe.com/biosci/bio_animations/02_MH_P
hotosynthesis_Web/ great review video
Steps of Photosynthesis
• Two main parts:
1. Light-dependent reaction
2. Light-independent reaction (Calvin Cycle)
6 CO2 + 6 H2O → C6 H12 O6 + 6 O2
(2)
(1)
(2)
(1)
Electron Carriers
• When light excites electrons (e-) in chlorophyll, they
gain energy
• These high-energy e- require a special carrier
• NADP+ is one e- carrier
• It is like an uncharged battery (like ADP)
• It turns to NADPH when charged
•
http://www.mhhe.com/biosci/bio_animations/02_MH_Photosynthesis_Web/
Light-Dependent Reaction
• Take place in the grana / thylakoid membrane (with
chlorophyll)
• Raw materials:
light, water,
ADP & NADP+
(uncharged
batteries)
• Products:
ATP,
NADPH (charged
batteries)
& O2 (given off into air)
http://www.sumanasinc.com/webcontent/an http://www.science.smith.edu/departme
• Video
Slower animation
imations/content/harvestinglight.html
Biology/Bio231/ltrxn.html
Step 2 – Light Independent
Reaction (Calvin Cycle)
• Raw materials: ATP, NADPH & CO2
• Products: C6H12O6
• Takes place in the stroma
Calvin Cycle – add to picture
• Uses ATP and NADPH from the light reactions to
produce high-energy sugars such as glucose.
• Uses 6 molecules of CO2 to produce one 6-Carbon
sugar.
• The sugar is either then used for immediate energy or to
build larger
molecules such as cellulose or
starch.
• Calvin cycle video clip
• http://highered.mcgrawhill.com/sites/0070960526/student_view0/
chapter5/animation_quiz_1.html
• Calvin cycle animation
• http://faculty.nl.edu/jste/calvin_cycle.htm
Overview of Photosynthesis
Factors Affecting Photosynthesis
a. Amount of water
b. Temperature (photo depends on enzymes
that work best at 0°C to 35°C (32oF to
95oF)
c. Light Intensity
d. CO2 concentration
e. surface area of leaves
Factors Affecting Photo
Photosynthesis Review
Round 1
Number your paper 1-8.
1. Name the energy storage molecule (the charged battery)._______
2. What are organisms called that can produce their own
food?_______
3. What molecule can be compared to a partially charged
battery?________
4. Name the ultimate source of energy for plants & animals._____
5. What are organisms called that get energy from other animals &
plants? ________
6. What is the location of the high energy bond in ATP? _________
7. What is the simple sugar that stores great amounts of energy?
________
8. The 3 parts of ATP are: ________, _________ & 3 _________.
Answers – Exchange papers with a
partner
Answers – Round 1
•
•
•
•
•
•
•
•
1.
2.
3.
4.
5.
6.
7.
8.
ATP
Autotroph
ADP
The sun
Heterotrophs
Between the 2nd & 3rd phosphate
Glucose
Adenine, ribose, 3 phosphates
Photosynthesis Review
Round 2
•
•
1.
2.
Number your paper 1-4
Match each scientist with their contribution to
photosynthesis:
Plants gain most of their mass through water.
Using a candle & a jar, he observed that plants
produce a gas that kept the candle burning.
3.
4.
Found that plants need sunlight to produce oxygen.
Traced the path in plants that produces glucose;
known as the light-independent reaction.
Priestly
Ingenhousz
van Helmont
Calvin
Answers – Exchange papers with a
partner
Answers – Round 2
•
•
•
•
1.
2.
3.
4.
van Helmont
Priestly
Ingenhousz
Calvin
Photosynthesis Review
Round 3
• Number your paper 1-9.
• 1. Write the equation for photosynthesis in symbols.
• 2. Write the equation for photosynthesis in words.
• 3. Plants gather light with molecules called _______; the main one
in plants is ____________.
• 4. Two areas of the visible spectrum that chlorophyll absorbs light
well from are ______ & ______.
• 5. Photosynthesis occurs in the _________ of plants.
• 6. Photosynthetic membranes in the chloroplasts are called
___________.
• 7. A ______ is a stack of thylakoids.
• 8. The _________ is the space outside the grana.
• 9. _______ can be compared to a device used to transfer hot coals.
• Answers – Exchange papers with a
partner.
Answers – Round 3
• 1. 6CO2 + 6H2O + light → C6H`2O6 + 6O2
• 2. carbon dioxide + water + light → glucose +
oxygen
• 3. pigment; chlorophyll
• 4. blue & red
• 5. chloroplasts
• 6. thylakoids
• 7. granum
• 8. stroma
• 9. NAPD+
Photosynthesis Review
Round 4
Number your paper 1-9.
1. The part of photosynthesis that requires light is called the
_____________ reaction.
2. The part of photosynthesis that does not require light is called the
_______ cycle.
3. Name 4 raw materials of the light- dependent reaction: ______,
______, ______ & ______.
4. Name 3 products of the light-dependent reaction:
______, ______ & ______.
5.
Name 3 raw materials of the Calvin cycle: _____, ______ &
________
6.
Name 1 product of the Calvin cycle: ________.
7.
The light-dependent reaction takes place in the _______.
8.
The Calvin cycle takes place in the ________.
9.
Name 3 factors that affect the rate of photosynthesis:
• Answers – Exchange papers with a
partner.
Answers – Round 4
1.
2.
3.
4.
5.
6.
7.
8.
9.
light-dependent
Calvin cycle (light-independent)
Light, water, ADP & NADP+
ATP, NADPH, & O2
ATP, NADPH & CO2
C6H12O6 (glucose)
grana
stroma
9. temperature, light & water
Photosynthesis Review
Round 5
•
1.
2.
3.
4.
Number your paper 1-8. Multiple Choice:
Which of the following is an autotroph:
A. cheetah
B. mushroom
C. fern
D. frog
One of the most important compounds that living things use to
store energy is:
A. DNA
B. ATP
C. H2O
D. CO2
Which scientist discovered oxygen?
A. Van Helmont B. Calvin
C. Priestly
D. Ingenhousz
The products of photosynthesis are:
A. sugar & oxygen
B. water & CO2
C. oxygen & hydrogen
D. sugar & carbon dioxide
Photosynthesis Review
Round 5
5.
6.
7.
8.
Which substance from the light-dependent reaction of
photosynthesis is a source of energy for the Calvin cycle?
A. ADP
B. H2O
C. NADPH
D. CO2
In which structures in a chloroplast does the Calvin cycle take
place?
A. stroma
B. grana
C. thylakoid
D. stacks of pancakes
The leaves of a plant appear green because chlorophyll:
A. reflects blue light
B. absorbs blue light
C. reflects green light
D. absorbs green light
Which molecule stores the most amount of energy?
A. ADP
B. ATP
C. fat
D. glucose
Answers – Round 5
1. C
2. B
3. C
4. A
5. C
6. A
7. C
8. D
• Answers – Exchange papers with a
partner