Photosynthesis
The Energy & Matter: Shaping
and Organizing Living Systems
CA Biology Standards
Students know usable energy is
captured from sunlight by chloroplasts
and is stored through the synthesis of
sugar from carbon dioxide.
 NGSS-HS-LS1-5. Use a model to
illustrate how photosynthesis transforms
light energy into stored chemical
energy.

Objectives
1.
2.
3.
4.
5.
6.
The conservation & transformation of energy & matter affect all
levels of life.
Organisms break the chemical bonds of food molecules,
forming different molecules with lower amounts of energy. As a
result, energy is released.
Many organisms have specialized cells, tissues, organs, and
organ systems to obtain and construct the molecules
necessary for life.
Photosynthesis transforms light energy into chemical energy.
Energy flows through ecosystems and matter cycles.
The flow of energy and the cycling of matter can help inform
current debates about the use of traditional and alternative
biofuel
Biofuel

Biofuel Video
What are the various forms of
energy that exist?
Write your answer in your journal.
 Energy is neither created nor destroyed.
 Energy is transferred from one form to
another.

Forms of energy

Potential energy-stored energy

Kinetic Energy-energy of movement of
objects
Transfer of Energy

Autotrophs (producers) are organisms
that create their own food by
photosynthesis (light energy)
Structure of a Leaf
Specialized
organelle for
photosynthesis is the
chloroplast.
Two main
compartments:
1. Thylakoid
2. Stroma
Visible Light
Why do plants appear
green?
Chlorophyll absorbs red & blue spectra and
reflects green wavelengths
Chlorophyll
Pigments can be
classified as which kind
of organic compound?
Lipids
ATP: The Cell’s Currency

Adenosine Triphosphate (ATP)

Energy from food is converted into high
energy bonds in ATP

ADP + P + energy  ATP
ADP
ATP
Energy
Adenosine diphosphate (ADP) + Phosphate
Partially
charged
battery
Energy
Adenosine triphosphate (ATP)
Fully
charged
battery
Overview of Photosynthesis

6 CO2 + 6 H2O + electron  C6H12O6 + 6 O2
Reactants
Products

Basis of most of the earth’s food chains

Produces and maintains all of the earth’s
atmospheric oxygen

Most oxygen produced in the oceans
Photosynthetic Pigments

Mostly chlorophyll a and chlorophyll b

Accessory pigments:
– Carotenoids
– Anthocyanins

Each pigment absorbs a particular wavelength of
light in the visible spectrum
At which wavelength does chlorophyll absorb the most
light? Least?
Pigment Absorption
Step I: Light Reactions







Occurs in thylakoid membrane of chloroplast
H2O is taken into plant by roots
Formation of O2 from H2O
H2O is oxidized by the splitting of water
(photolysis)
Light energy is converted into chemical bond
energy
ATP, NADPH, H+, and O2 are generated
12 H2O + Energy  6 O2 + 24 H+ + 24e-
Overview of the Light Reactions

Think of the light reaction, as a process
by which organisms "capture and
store" radiant energy as they produce
oxygen gas.

This energy is stored in the form of
chemical bonds of compounds such as
NADPH and ATP.
Step II: Light Independent
(Calvin Cycle)

Occurs in the stroma (No light necessary)

The energy from NADPH and ATP is used for
carbon fixation (converting inorganic carbon
to organic compounds)

Formation of glucose from CO2

6 CO2 + 24 H+ + 24 e- ------> C6H12O6 + 6 H2O

The chemical bonds present in glucose also
contain a considerable amount of stored (potential)
energy.
Guard Cells-open or close based on
turgor pressure
Overview of the Dark Reactions

Carbon dioxide is broken and “fixed” into
glucose or fructose molecules in the CALVIN
CYCLE!!!!

Glucose subunits can make cellulose or other
polysaccharides, such as fruit sugars.
Video Clip-Teacher Domain

http://www.pbslearningmedia.org/resour
ce/tdc02.sci.life.stru.photosynth/photosy
nthesis/
Light
CO2
ATP
ADP + P
LightDependent
Reactions
Calvin
Cycle
NADP+
Sugars
O2
Chloroplast
NADPH
Factors Affecting Photosynthesis
 Water
 shortage of water can slow/stop photosynthesis.
 Desert plants have waxy coating on leaves
(reduce water loss)
 Temperature
 Photosynthesis depends on enzymes which
function best between 0°C and 35°C.
 Temperatures above or below can damage
enzymes, slowing down enzyme activity.
 Intensity of light
Quiz
Complete the sentences below:
1. Energy is neither _______ nor
__________. It is merely
__________into another form.
2. When bonds break, energy is
_________. When bonds form, energy
is _________.
Select the best answer choice for
the following statements.
3. The specialized organelle in which
molecules of glucose are formed is the
a.
b.
c.
d.
e.
Mitochondria
Nucleus
Cell membrane
Chloroplast
Chlorophyll
4. During photosynthesis, light is
transformed to
a.
b.
c.
d.
Mechanical energy
Chemical energy
Heat energy
Electrical energy
5. Energy flows through ecosystems
beginning with
a.
b.
c.
d.
e.
Producers
Heterotrophs
Decomposers
Carnivores
Sunlight
1.
2.
What are some of the advantages of
using plants to generate biofuel?
What are some disadvantages of using
plants to generate biofuel?
Photosynthesis Recipe

Complete the photosynthesis recipe
card for homework.