Chapter 8 Photosynthesis PTHS

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SECTION 8-1
ENERGY and LIFE
Question of the Day
OCT 25
 Which of the following organisms is an
autotroph?
 A. Giraffe
 B. Antelope
 C. Maple tree
 D. Polar bear
DO NOW
IT’S BACK!!!
OCT 25
 ADAM C., NICOLE L., and TYLER

 YOU are the next contestants on
DO NOW CHALLENGE!!!
DO NOW CHALLENGE
OCT 25
Explain why plants have a key
role in the survival of all living
things.
Answer the DO NOW in your
notes if you are at your desk.
DO NOW ANSWERED
 Plants (and some algae) perform photosynthesis. They
produce their own food in the form of sugar.
 Other living organisms depend on this source of food
to power their own cells.
 Ultimately, all life is dependent upon plants from the
smallest herbivore to the pinnacle predators of our
planet.
AGENDA
OCT 25
 BIG Question: How do organisms obtain and store
energy?
 1. QoD and DO NOW
 2. Introduce Chapter 8 Photosynthesis
 3. Review Guided Notes Packet
 4. REVIEW
 5. HOMEWORK and Closing Thoughts
AUTOTROPHS AND HETEROTROPHS
 What is the key source of energy for most food?
 THE SUN
 Plants and other organisms such as blue-green algae
use light energy from the sun to produce food.
 These organisms are called AUTOTROPHS.
 Use simple inorganic molecules to do this.
AUTOTROPHS and HETEROTROPHS
 Heterotrophs are organisms that obtain energy from the
food they consume.
 Unable to use sunlight directly.
 ALL organisms must release energy in sugars and other
compounds.
CHEMICAL ENERGY and ATP
 What are three forms of energy?
 Light, heat, and electricity
 Energy can be stored in compounds.
 Electrons release energy when a piece of wood is set
on fire.
 When chemical bonds are broken and electrons shift
from higher energy levels to lower energy levels, the
extra energy is released as light and heat.
CHEMICAL ENERGY and ATP
 How do organisms such as
humans store and release
energy?
 Cells use chemical
compounds to do this.
 What is ATP?
 Adenosine Triphosphate
(ENERGY storing
molecule)
 ATP consists of ADENINE, a
5-CARBON SUGAR, and
3 PHOSPHATE GROUPS
STORING ENERGY
 What is ADP?
 ADENOSINE DIPHOSPHATE
 2 PHOSPHATE GROUPS
 Partially charged battery
 This is the key molecule organisms use to store excess
energy when it is available.
 To store energy, a PHOSPHATE group is added to ADP.
 This creates a molecule of ATP.
 ATP is like a fully charged battery. WHY?
RELEASING ENERGY
 How is stored energy released from ATP to be used by the
cell?
 Energy is stored in the chemical bond between the
second and third phosphate groups.
 Breaking this bond releases the energy stored in it.
RELEASING ENERGY
 ATP is the basic energy source for all cells.
 What are different cellular functions that ATP can power
within the cell?
 ACTIVE TRANSPORT
 PROTEIN SYNTHESIS
 MUSCLE CONTRACTION
USING BIOCHEMICAL ENERGY
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What is a SODIUM – POTASSIUM Pump?
Used during Active Transport
It pumps Na- ions out of the cell and K+ ions into it
Balance of ions must be carefully regulated.
 Why do most cells only have a small amount of ATP?
 Not a good molecule for storing large amounts of energy
over a long period of time.
 Glucose stores 90 times more energy than ATP
 Cells regenerate ATP from ADP as they need it.
QUESTION OF THE DAY OCT 28
Where is energy stored in a molecule of ATP?
a. The phosphate groups
b. The ribose
c. The bond between the first and second
phosphates
d. The bond between the second and third
phosphates
DO NOW CHALLENGE OCT 28
 STEP UP to the boards.
 Answer the Challenge in your notes if
you are at your desks.
DO NOW CHALLENGE
OCT 28
 Compare a molecule of ATP and
Glucose.
 How are they similar/different in their
role of storing energy?
ANSWER
OCT 28
 ATP is the cell’s short term energy storing molecule.
Energy is stored within ATP in the chemical bond
formed between the second and third phosphate
groups of the molecule. In order to release this
energy, the bond must be broken.
 Glucose is a monomer that forms carbohydrates.
Many of these simple sugars form glycogen. It is used
to store sugars for long term energy use.
 THANK YOU FOR PLAYING DO NOW CHALLENGE!!!
AGENDA
OCT 28
 BIG QUESTION: How did early experiments lead to
the discovery of photosynthesis?
 1. QoD and DO NOW
 2. Section 8-2 Photosynthesis: An Overview
 3. Discovery of Photosynthesis
 4. Homework Check
 5. Review and Homework
 6. Return CH 7 Tests and Cell Booklets
8-2 Photosynthesis: An Overview
 What is PHOTOSYNTHESIS?
 Plants use the energy of sunlight to convert water and
carbon dioxide into high energy carbohydrates
 Sugars and starches
 And Oxygen, a waste product.
Investigating Photosynthesis
 As a tree grows bigger and bigger in size, where does
the tree’s increase in mass come from?
 SOIL, WATER, AIR?
 This simple question asked hundreds of years ago began
the research into photosynthesis.
 Let’s take a closer look at some of the experiments that led
to the discovery of photosynthesis…
Van HELMONT’S Experiment
 1643, Belgian physician Jan van Helmont.
 What did he do?
 Designed an experiment to investigate if plants grew
by taking materials out of the soil.
 His experiment?
 1. Determined mass of a pot of dry soil and a
seedling.
Van HELMONT Experiment
 2. Planted the seedling in the pot of soil.
 Watered regularly.
 3. At the end of 5 years, the seedling had grown into a
small tree. Mass gain of 75 grams.
 4. Mass of soil remained almost unchanged.
 5. His Conclusion
 Mass of the tree came from the water – only thing he
added.
 Accounted for the “HYDRATE” portion of a
CARBOHYDRATE
 Where does the “CARBO” portion come from?
 Carbon Dioxide
Priestley’s Experiment
 1771, English minister Joseph Priestley
 What did he do?
 Lit a candle, placed a jar over it, and watched the
flame gradually die out.
 What did he reason about the candle flame?
 Something in the air was necessary to keep the candle
burning.
Priestley’s Experiment
 What was his next step?
 He placed a spring of mint underneath the jar with the
candle.
 After a few days, Priestley realized that the candle could be
relighted.
 It would remain burning for a period of time.
 His conclusion?
 The mint sprig released something needed to keep the
candle flame burning.
 What was this mystery substance?
 OXYGEN
The Ingenhousz Experiment
 1779, Dutch scientist Jan Ingenhousz
 What did he do?
 Showed the effect observed by Priestley only occurred
when the plant was exposed to light.
 What did these experiments show?
 When a plant is exposed to light, it transforms carbon
dioxide and water into carbohydrates and release
oxygen.
PHOTOSYNTHESIS EQUATION
 What is the balanced equation of photosynthesis?
 Compare the equation of photosynthesis with
another cellular process.
Light and Pigments
 White light is actually a mixture of different
wavelengths of light called the visible spectrum
 Different wavelengths of visible light are seen as
different colors.
Light and Pigments
 What is a pigment?
 colored substances that absorb or reflect light
 Why are plants green?
 chlorophyll: principle pigment in green plants
 Absorbs red and blue-violet light in the visible
spectrum.
 Chlorophyll a and Chlorophyll b
 Does not absorb green light
well.
Leaves reflect green light
Which is why plants look green.
ABSORPTION OF LIGHT
 B – carotene
 Red and orange pigments that absorb light in other
regions of the spectrum.

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