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IB Biology
Student Notes
The World of Plants:
Photosynthesis and More
A. Introduction
What is the point of photosynthesis?
B. Plants and other autotrophs are the producers of the
biosphere.
1. Autotrophs=
2. Types of autotrophs
a. Photoautotrophs -
b. Chemoautotrophs -
3. Heterotrophs =
C. Chloroplasts are the sites of photosynthesis in plants.
1. Where are chloroplasts located?
2. What is chlorophyll?
3. What is the structure of a chloroplast?
D. Evidence that water split
water molecules enabled
researchers to track atoms
through photosynthesis.
1. What is the balanced equation
for photosynthesis?
2. Where did scientists originally believe oxygen came from in
the photosynthetic process?
3. How did C.B. van Niel challenge this?
4. How did other scientists confirm van Niel's theory by using
O-18 as a tracer? What did they find?
5. Why is photosynthesis considered a "redox" reaction?
E. The light reactions and the Calvin cycle cooperate in
converting light energy in chemical energy of food: an overview.
1. Photosynthesis occurs in two stages:
a. The Light Reactions-
b. The Dark Reactions -
F. Light, Leaves and Photosynthesis
1. How does light travel?
F. Light, Leaves and Photosynthesis
1. What do the thylakoids do?
2. Wavelength =
3. Visible light is the part of the electromagnetic spectrum
between 380-750 nm.
4. What is a photon?
5. Why do we see colors?
6. If we see white, that means...
7. If we see black, that means...
8. Why does chlorophyll look green?
9. What wavelengths of light are absorbed most by chlorophyll?
10. Application questions
a. Why do pet stores sell fish tank lights that illuminate the
color green?
b. What would happen if you grew plants only in green
light?
Only in red and blue light?
c. How can you set up an expt. in the lab to show the
effects of wavelength of light on plant photosynthetic
efficiency?
11. Types of photosynthetic pigments
a. Chlorophyll a -
b. Chlorophyll b-
c. Carotenoidsd. How do accessory pigments aid in photosynthesis?
e. What did Thomas Engelmann in 1883 demonstrate?
(theme - Science as a Process)
f. What happens to photosynthetic pigments when photons
of light are absorbed?
g. What is a "photosystem"?
h. Types of photosystems
1. Photosystem I -
2. Photosystem II -
These two systems work together to use light energy to
generate…
1.
2.
i. Two Routes for Excited Electrons:
1. cyclic-
2. noncyclic-
G. Cyclic Photophosphorylation
1. What happens in cyclic photophosphorylation?
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2. What do you really need to remember about cyclic
photophosphorylation?
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H. Noncyclic photophosphorylation
1. What happens?
a. Photons begin by exciting electrons in photosystem
P700. What happens to these excited electrons?
b. What is produced as a result of this electron transport
chain and why is this product important?
c. What molecule ends up with the electrons, and becomes
reduced as a result?
d. Why is this important?
e. How is the electron void in P700 filled?
f. What is made as a result?
g. How is the electron void in P680 filled?
h. What is formed when water splits?
 Oxygen->
 Hydrogen ...which splits into electrons and protons
(H+)
 Where do the electrons go?
 Where do the H+ ions go?
2. Summary of the noncyclic electron flow- What do you really
need to know?
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I. How does the structure of a chloroplast aid in its function?
1. How does chemiosmosis in chloroplasts work?
a. H+ ions are pumped to______________________.
b. Due to the high concentration, H+ ions move
by facilitated diffusion to ___________________.
c. As H+ ions are transported they move through
a special integral protein called the _________.
d. The energy derived from moving H+ ions down
their concentration gradient is used to add
the terminal phosphate back on to ADP to
form ATP.
e. Thus, ATP is made in what part of the chloroplast?
f. What will the ATP be used for?
g. What is the pH of the thylakoid space?
2. How does chemiosmosis in photosynthesis compare to that
in respiration?
3. What are all of the names of the Light Reactions of
photosynthesis?
a.
b.
c.
J. What comes next? The Calvin Citric Acid Cycle
1. Overview –
-The calvin cycle
its starting material after molecules
enter and leave
-CO2 enters the cycle and leaves as…
-The cycle spends the energy of
.
and the
electrons carried by NADPH from the
of
to make
the sugar.
-The actual sugar product is not glucose, but a
2. What are other names of the Dark Reactions?
a.
b.
c.
3. The Calvin Cycle has three phases:
a. The Carbon-fixation phase
o Starting reactant?
o Reaction?
o Enzyme?
o Product?
b. The Reduction phase
.
o What molecules
get used from the light
reactions in this phase?
o Products formed?
o How many?
o What becomes of the six G3P (PGAL) molecules?
c. The Regeneration phase
o What molecule is regenerated? Why?
o How is this phase "fueled"?
o Numbers? How many G3P make how many RUBP
molecules?
4. What do you really
need to know about the
Calvin cycle?
a. Starting with 6 carbon
dioxide molecules...spins
the cycle
_______________times.
b. How many G3P (PGAL) molecules come out of the cycle?
c. What can these be synthesized into?
d. Why is this kind of sugar production known as "C3
Photosynthesis"?
e. 2 G3P -> ___________ glucose -> ______________
5. Describe Melvin Calvin’s “lollipop” experiment.
6. Tracing atoms in photosynthesis:
K. Overall Requirements and Products of Photosynthesis.
L. How do plants get the CO2 they need and get rid of excess
oxygen?
1. Stomates –
2. Lenticels -
M. Label the diagram
N. What happens to the end products of photosynthesis?
1. The sugar made in the Calvin cycle has many
possible paths...
a. 50% of it is used for _____________________.
b. Where does the sugar made in the leaf
travel to?
c. What can the sugar be made into?
d. How can excess sugar by stored?
e. How do heterotrophs benefit from
photosynthetic products?
O. How does photosynthesis compare/contrast to cellular
respiration?
1. Write the balanced equation for aerobic respiration below:
2. Write the balanced equation for photosynthesis below:
3. How do they compare/contrast?
4. How do the organelles compare and contrast?
a. Similarities between the chloroplast and the
mitochondria?
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b. Other similarities?
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5. Differences between photosynthesis and respiration:
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P. Global Artificial photosynthesis- The future?
1. Benefits?
2. Limitations?