Biology
Ch.7 Photosynthesis
Notes Unit 3 LT1,2
LT1 Cell Metabolism
LT1a I can connect anabolism, catabolism, and enzymes to the concept of cell metabolism.
Metabolism: All of an organism’s chemical reactions.
Anabolism: the synthesis of complex molecules in
living organisms from simpler ones together with the
storage of energy; constructive metabolism.
Catabolism: the breakdown of complex molecules in
living organisms to form simpler ones, together with the
release of energy; destructive metabolism.
Enzymes are biological catalysts that lower the energy
of activation for a chemical reaction (metabolism) to
cellular temperatures.
LT1b I can list the parts of an ATP molecule
and draw them properly connected.
List:
adenine
ribose sugar
three phosphate groups
LT1c I can demonstrate how an ATP molecule
is made and broken down for energy.
LT1d I can create an organizer that shows how anabolism, catabolism, cell metabolism,
ATP, photosynthesis, and cell respiration are all connected
There is a study sheet on Weebly, “Coupled Reactions” for you to use for this learning
target or you are free to create your own.
The study sheet includes:
Mrs. Loyd
cloyd@waukee.k12.ia.us
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LT2 Anabolism---Photosynthesis
LT2a I can state the overall goal of photosynthesis, the organelle in which it occurs, and its two main stages.
An Overview of Photosynthesis
Define autotrophs, producers, and photoautotrophs.
Autotrophs: “self-feeders” They make their own food and
sustain themselves without other organisms.
Producers: Using the energy from the sun and chlorophyll,
these organisms make their own glucose which is used
by other organisms as food. Producers are always the
base of the food chain.
Photoautotrophs: All organisms that produce organic
molecules from inorganic molecules using the energy of
light.
LT2a I can state the overall goal of photosynthesis, the organelle in which it
occurs, and its two main stages.
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Describe the structure of chloroplasts
Essentially; it is two spaces separated by a membrane.
Thylakoid membrane encloses a space called “thylakoid space”
A stack of thylakoids is called a granum or granal stack
Space surrounding thylakoids is the stroma
Chlorophyll and photosynthetic enzymes are embedded in thylakoid
membrane the site of the conversion of light into chemical energy.
Describe the location of chloroplasts in a leaf
Chloroplasts are located in mesophyll cell (means: “middle leaf”)
Mesophyll:
Palisade mesophyll: most photosynthesis
Spongy mesophyll: surrounds stoma
How do the reactant molecules of photosynthesis (CO2 + H2O) reach the chloroplasts in
leaves? How does leaf structure promote this process as well as light absorption?
Mrs. Loyd
cloyd@waukee.k12.ia.us
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http://loydbiology.weebly.com
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http://www.mybiology.com
LT2a I can state the overall goal of photosynthesis, the organelle in which it occurs, and its two main stages.
SUMMARY:
The light reactions convert light energy into the
chemical energy of ATP.
The Calvin cycle uses the ATP as the energy
to build 6CO2 + 6H2O into C6H12O6.
LT2b I can list the beginning and ending
molecules for each of the two stages of
photosynthesis.
Light
Rxn
Calvin
Cycle
Reactants
H2O
NADP+
ADP + P
light energy
CO2
ATP
NADPH (e-s)
Products
O2
ATP
NADPH (e-s)
NADP+
ADP + P
glucose
The Light Reactions: Converting Solar Energy to Chemical Energy
Describe the properties and functions of the different photosynthetic
pigments.
LIGHT ENERGY
Electromagnetic Spectrum of Energy:
Gamma – X-rays – UV – visible – Infrared – Microwaves – Radiowaves
Visible light spectrum:
Red Orange Yellow G.reen Blue Indigo Violet
Infrared – ROY G. BIV – Ultraviolet (UV)
(heat lamp)
(sunburn/skin cancer)
Mrs. Loyd
cloyd@waukee.k12.ia.us
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Plant Pigments
Why are plants green?
Reflected wavelengths (color) reach our eyes and we see green.
Is green light important to plants?
No, green light is reflected or “thrown away.”
Pigment properties and functions
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Pigments absorb light of different wavelengths
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Chloroplasts contain several kinds of pigments
o Chlorophyll a: absorbs blue-violet, looks grass
green
o Chlorophyll b: absorbs blue and orange, looks
yellow-green
o Carotenoids: absorb , look yellow to orange
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More kinds of pigments broadens the spectrum of colors
that can drive photosynthesis.
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All pigments must pass energy absorbed to chlorophyll a,
which serves as the reaction center of photosystems.
Why do leaves change color and drop in autumn?
1. The change to cold weather causes the most sensitive
and abundant pigment, chlorophyll a, to break down and
disappear from the mesophyll cells in leaves.
2. The colors of the other pigments particularly the
carotenoids, previously masked by chlorophyll a, are
revealed.
3. Bright reds, oranges, and yellows are typical in the fall.
4. Once the temperature falls more drastically, the remaining
pigments breakdown and the leaves turn brown.
5. Abscisic acid is released by the tree to cause the leaves to
abscise or drop thus greatly reducing surface area and
water loss during winter.
Mrs. Loyd
cloyd@waukee.k12.ia.us
Page 4 of 4
http://loydbiology.weebly.com
10/20/11
http://www.mybiology.com