Transcript Ch 8 102 Photosyn[1]

Georgia Performance Standards- Relate the complexity and organization of
organisms to their ability for obtaining &
transforming the matter and energy used to sustain
the organisms.
Essential Questions:
- How does and energy flow through a plant?
Hook
Suppose you earned extra money by having a parttime job. At first, you might be tempted to spend
all of the money, but then you decide to open a
bank account.
1. What are the benefits of having a bank account?
2. What do you have to do if you need some of this
money?
3. What might your body do when it has more
energy than it needs to carry out its activities?
4. What does your body do when it needs energy?
• All living things need
energy. Some are
more obvious than
others. Are we still
using energy while we
sleep?
• Where does energy
come from?
Photosynthesis
ENERGY and LIFE
Every living things requires energy (from food) to survive.
Autotrophs: make their own food (plants)
Heterotrophs: consume their food (animals, fungi, yeasts)
Chemical energy = energy stored in molecules
How do cells store energy?
1. ATP - Adenosine triphosphate
*Easy for cells to use
*Basic energy source for cells; used to power
cell
processes. Ex: active transport
*Good at transferring E; Cannot store large
amounts of energy for long amounts of time
Comparison of ADP and ATP to a Battery
ADP
ATP
Energy
Adenosine diphosphate (ADP) + Phosphate
Partially
charged
battery
Energy
Adenosine triphosphate (ATP)
Fully
charged
battery
How do cells store energy?
2. Glucose
*Lots of energy (90 times more than 1 ATP molecule)
*Not as accessible for cell processes, better for
storage
*Can be used to make more ATP (ADP-> ATP)
Checkpoint Questions:
1.
What is the ultimate source of energy for plants?
1.
What is ATP and what is its role in the cell?
3. Describe cellular activities that use the energy released by ATP.
4. How do autotrophs obtain energy? How do heterotrophs obtain
energy?
5. With respect to energy, how are ATP and glucose similar? How
are they different?
Warm-up: Trapping Energy
• Have you ever used a solar-powered
calculator?
• No matter where you go, as long as you
have a light source, the calculator works.
You never have to put batteries in it.
Warm-up: Trapping Energy
1. A solar-powered calculator uses
solar cells that are found in
rows along the top of the
calculator. Into what kind of
energy is the light energy
converted so that the calculator
works?
2. Recall that plants use light
energy from the sun to make
food. Into what kind of energy
is the light energy converted by
plants?
3. Most plants, no matter what size
or shape they are, have some
parts that are green. Which
parts of a plant are usually
green?
4. What does the green color have
to do with the plant’s ability to
convert light energy into the
energy found in the food it
makes?
How do cells get ATP and glucose?
PHOTOSYNTHESIS
Photosynthesis – Plants use energy from
sunlight to convert H2O and CO2 into O2 and
sugars.
Seedling  Tree
Experiments that help us understand
photosynthesis
Jan van Helmont (1643)
Question: Do plants gain mass
(grow) by taking material out
of the soil?
Experiment: Over 5 years, he
measured the mass of the
soil and the plant.
Conclusion: Mass of plant
comes from water, not soil.
Experiments that help us understand
photosynthesis
Joseph Priestley (1771)
Question: Why does a candle remain
burning under a jar when a plant is
under the jar?
Answer: A plant produces a
substance (oxygen) required for
burning.
Experiments that help us understand
photosynthesis
Jan Ingenhouz (1779)
Repeated Priestley’s experiment in light and
dark.
Question: Does light affect the candle
burning when a plant is present?
Answer: Light is required for plants to
produce oxygen.
Experiments that help us understand
photosynthesis
From these experiments we know:
With light, plants transform water and carbon
dioxide into carbohydrates and oxygen
How do plants use light?
Light is a form of energy
Pigments - molecules that absorb specific wavelengths
of light
Chlorophyll - main pigment found in plants
Two types: Chlorophyll A and Chlorophyll B;
What colors do they absorb easily?
Light & Chlorophyll Pigments:
• Photosynthesis Also Requires Light and Chlorophyll
Pigments
• Sunlight is seen as white light (a mixture of different
wavelengths of light)
– Wavelengths of visible light are seen as certain colors
• Review Spectrum of visible Light
• Plants appear green because that is the color that is
reflected.
• The other colors of light are being absorbed.
Chlorophyll Light Absorption
Absorption of Light by
Chlorophyll a and Chlorophyll b
Chlorophyll b
Chlorophyll a
V
B
G
YO
R
Photosynthesis requires light and chlorophyll, which absorbs light energy. In the
graph, notice how chlorophyll a absorbs light in the violet and red regions of the
visible spectrum, while chlorophyll b absorbs light in the blue and red regions of the
visible spectrum.
Checkpoint:
1. Describe the process of photosynthesis, including
the reactants and products.
2. Why are light and chlorophyll needed for
photosynthesis?
3. Why are plants green?
4. How well would a plant grow under pure yellow
light? Explain your answer.
How do plants use light?
*When chlorophyll absorbs light, it absorbs energy
*That energy is transferred to electrons
*Those electrons power photosynthesis
Electron carriers - molecules that transfer high
energy electrons from chlorophyll to other
molecules
Example:
NADP+ (nicotinamide adenine dinucleotide
phosphate) can accept 2 high energy electrons.
2 electrons + NADP+ -> NADPH
Photosynthesis takes place in the
chloroplast of the cell.
Stroma - space outside the thylakoids
granum - stack of thylakoids
grana - plural of granum
thylakoid - membrane sacs that contain pigments to
absorb light energy
Two parts to photosynthesis:
1. Light Dependent Reactions - process that
uses light to produce oxygen, ATP, and NADPH.
Occurs in the thylakoid membrane
2. Light Independent Reactions (Calvin Cycle) process that uses ATP and NADPH to produce
high energy sugars. Occurs in the stroma.
Light Dependent Reactions
• Require Light !!
• Occurs in the
thylakoid membranes
• Produce oxygen and
convert ADP and
NADP+  ATP and
NADPH
• Basic Goal- Light 
Chemical Energy
Light Dependent Reactions
Photosystem II: E from
light is absorbed by
chlorophyll and
transferred to
electrons; then, these
high E electrons are
passed to the
Electron Transport
Chain
Photosystem I :
Pigments use light to reenergize the electrons
Calvin Cycle AKA LightIndependent Reactions
• Basic Goal: Takes the
Chemical Energy and
Converts it to High
energy sugars (ex.
Glucose)
• Occurs in Stroma!!!
• Uses ATP and
NADPH to produce
high energy sugars
Concept Map
Section 8-3
Photosynthesis
includes
Lightdependent
reactions
Calvin cycle
use
take place in
Energy from
sunlight
Thylakoid
membranes
to produce
ATP
Go to
Section:
NADPH
O2
takes place in
Stroma
uses
ATP
NADPH
of
to produce
Chloroplasts
High-energy
sugars
What Affects Photosynthesis???
• Shortage of water
• Temperature (Best at
0-35 degrees Celsius)
• Intensity of light.
Checkpoint:
1.
Summarize the light-dependent reactions.
2.
What reactions make up the Calvin cycle?
3. What is the function of NADPH?
4.
How is light energy converted into chemical energy
during photosynthesis?
5.
Can the complete process of photosynthesis take place in
the dark? Explain your answer.