Honors Biology
Ch.7 Photosynthesis
Notes
An Overview of Photosynthesis
7.1 LT2 I can explain the roles of autotrophs (producers) and
heterotrophs (consumers) in how energy is transferred in nature.
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.
Examples:
Prokaryotes: cyanobacteria (aquatic)
Eukaryotes:
Plants (both aquatic and terrestrial)
protists (like euglena, kelp, green algae) (aquatic: both marine and
fresh water)
LT #1M
7.2 Describe the structure of chloroplasts and their location in a leaf. Identify
specifically where most light energy is converted to chemical energy.
Describe the structure of chloroplasts
Double membrane organelle
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.

Essentially; it is two spaces separated by a membrane.





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?
7.3
Explain how plants produce oxygen
Plants produce oxygen when water (H2O) is split in the stroma. The hydrogen is
used to make sugar and the excess oxygen diffuses out of the leaf.
Mrs. Loyd 
cschmittloyd@waukeeschools.org
Page 1 of 5
7/12/16
http://loydbiology.weebly.com
7.5
Light
Rxn
Calvin
Compare the reactants and products of the light reactions and the Calvin cycle. Explain how photosynthesis relates to
these reactions.
Reactants
H2O
NADP+
ADP + P
light energy
CO2
ATP
NADPH (e-s)
Products
O2
ATP
NADPH (e-s)
NADP+
ADP + P
glucose
Explain how photosynthesis relates to these
reactions.
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.
The Light Reactions: Converting Solar Energy to Chemical Energy
7.6
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)
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

Pigments absorb light of different wavelengths

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

More kinds of pigments broadens the spectrum of colors
that can drive photosynthesis.

All pigments must pass energy absorbed to chlorophyll a,
which serves as the reaction center of photosystems.

Accessory pigments also provide photoprotection from
damaging UV rays for chlorophyll a.

Why do things fade in the sun? Photodegradation https://www.youtube.com/watch?v=9e__f8Ydu8Q&list=TLU-35dfyLkmA
Why do leaves change color and drop in autumn?
Mrs. Loyd 
cschmittloyd@waukeeschools.org
Page 2 of 5
7/12/16
http://loydbiology.weebly.com
1.
2.
3.
4.
5.
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.
The colors of the other pigments particularly the
carotenoids, previously masked by chlorophyll a, are
revealed.
Bright reds, oranges, and yellows are typical in the fall.
Once the temperature falls more drastically, the remaining
pigments breakdown and the leaves turn brown.
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.
SUMMARY
Compare and contrast photosynthesis with cellular respiration
Abbrev. of e- carriers:
____________
____________
Ch.18.3 Energy Transfer
LT2 I can explain the roles of autotrophs (producers) and
heterotrophs (consumers) in how energy is transferred in nature.
Producers: Most producers are photosynthetic and make
carbohydrates by using energy from the sun.
Consumers obtain energy by eating other organisms and include:

herbivores

omnivores

carnivores

detritivores

decomposers
Decomposers feed on dead organisms and wastes, which releases
the nutrients back into the environment.
Food Chains and Webs
A single pathway of energy transfer is a food chain.
A network showing all paths of energy transfer is a food web.
Trophic Levels “Feeding levels”
Ecosystems contain only a few trophic levels because there is a
low rate of energy transfer (10%) between each level.
Therefore, there are always fewer predators than prey.
Mrs. Loyd 
cschmittloyd@waukeeschools.org
Page 3 of 5
7/12/16
http://loydbiology.weebly.com
18.4 Ecosystem Recycling
An ecosystem consists of all the organisms in a community as well as the abiotic
environment with which the organisms interact.
Compare the movement of energy and chemicals through nature.
“Matter cycles, energy flows.”
LT2a I can use a model to explain how cellular respiration and
photosynthesis are examples of interdependence.
LT 2c I can discuss how the molecules of the water cycle and
carbon cycle are conserved as they move trough living and
nonliving factors.Water Cycle

evaporation

transpiration

precipitation
Carbon
(Depends
on
Photosyn.
& Cell
Resp.)
Biotic Reservoir
Plants draw CO2 out of air into sugar
Passed along food chain by consumers
Cellular Resp. returns CO2 to atmosp.
Decomposers break down carbon
compounds in detritus and releases it as CO2
Burning wood and fossil fuels releases large
amts of CO2 back into the air.
Abiotic Reservoir
Atmospheric
Fossil fuels
Dissolved carbon
compounds in oceans
Sedimentary rocks like
CaCO3
Carbon Cycle

photosynthesis

cellular respiration

burning fossil fuels

decomposition
Mrs. Loyd 
cschmittloyd@waukeeschools.org
Page 4 of 5
7/12/16
http://loydbiology.weebly.com
LT #3 I can describe the evolutionary significance of
glycolysis, fermentation, photosynthesis and cellular
respiration.
LT3a I can explain why life would probably NOT have
evolved had free oxygen (O2) been present in the
atmosphere.


Oxygen is a strong oxidizer meaning it pulls electrons
away from most other elements. Because it is an
"electron hog" (high electronegativity), it reacts
aggressively.
If O2 (free oxygen) had been present in the Earth's early
atmosphere, it would have oxidized molecules and kept
them small and simple.
LT3b I can describe the first life on the planet, how it
harnessed energy and I can give an example of a modern
analog.
First Life

NO oxygen:
anaerobic

NO photosynthesis:
heterotrophic

NO nucleus or organelles: prokaryotic
How first life harnessed energy

Glycolysis and Fermentation were the first energy
releasing metabolic reactions. This would be similar
to modern day bacteria that are not photosynthetic.
LT 3c I can provide evidence to support the claim that
glycolysis is an evolutionary relic.
1.
2.
3.
Universal (it evolved very early and was passed down so
that, today, all organisms use glycolysis.
Does not require oxygen. The early Earth atmosphere
had no oxygen. The earliest reactions could not have
required it.
Does not require membrane-bound organelles. The
earliest cells were prokaryotic. They do not have cell
organelles.
LT 3d I can compare the amount of ATP produced by
anaerobic respiration with that of aerobic respiration and
infer the impact this adaptive advantage had on life after
aerobic respiration evolved.



Aerobic respiration produces (36 ATP) 18 times more ATP
than anaerobic respiration can (2 ATP).
As the population of prokaryotic cells multiplied and the
supply of organic molecules dwindled, competition for
those molecules would be fierce.
When aerobic respiration evolved, these individuals would
not need to compete for food at all conserving energy and
allowing more offspring that shared this adaptive
advantage while other cell types went extinct.
LT 3e I can explain and provide evidence for the
endosymbiotic theory for the evolution of mitochondria
and chloroplasts.
1.
2.
3.
4.
Both have their own DNA and their DNA is circular like
prokaryotes NOT the eukaryotes (linear) they are in.
They have ribosomes that resemble prokaryotic
ribosomes, NOT the eukaryotic ribosomes of the cell they
are in.
They are the size of prokaryotic cells.
They have double membranes that may have resulted
from endocytosis.
Mrs. Loyd 
cschmittloyd@waukeeschools.org
Page 5 of 5
7/12/16
http://loydbiology.weebly.com