Transcript Chapter 8: Photosynthesis

Chapter 8: Photosynthesis
Energy and Life
Rainy Day
• Suppose you earned extra money from a parttime job. You might be tempted to spend all the
money, but instead, you decide to open a
savings account.
• 1. What are the benefits to having a bank account?
• 2. What might you need to do if you need some of this money?
• 3. What might your body do if it has more energy than it needs
to carry out its activities?
• 4. What would your body do if it needed more energy?
Energy and Life
A. Autotrophs and heterotrophs
1. Autotrophs can make own food directly with aid of
the sunlight.
a. plants
2. Heterotrophs cannot make own food directly.
Depends on others such as plants for food.
a. Humans
b. Mushrooms-need to decompose other organisms
Chemical NRG and ATP
• Energy=in the form of light, heat, electricity
• ATP (Adenosine Tri Phosphate)
– Most important energy storing compound
ATP and ADP
• ATP (Adenosine Tri Phosphate)
– Fully charged energy
– Uses enzymes to break down to make energy
– Energy is released when ATP breaks down to
ADP and a phosphate group
• ADP (Adenosine Di Phosphate)
– Not fully charged energy
– Needs enzymes to help add one more
Phosphate to make ATP
ATP and cells
• Cells use ATP when they move and during
active transport
• Most cells have a little amount of ATP,
enough to last for seconds.
– ATP is not good at storing over a long period
of time but it is VERY efficient when used.
Glucose
• A monosaccharide sugar, C6H12O6,
occurring widely in most plant and animal
tissue. It is the principal circulating sugar
in the blood and the major energy source
of the body.
• Stores more than 90 times more chemical
energy than ATP
• Cells can get ATP and ADP from carbs.
Photosynthesis
• Photosynthesis-plants use energy of the
sun to make food such as, glucose.
Scientists
• van Helmont
– How does a seed grow into a tree?
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Weighed a pot of soil and seed = 5 kg
Watered for 5 years
Seed gained about 75 kg
The soil was unchanged throughout
He concluded that water made the seed grow into
a tree.
Is that all that is needed to make plants grow?
NO!!! Plants need:
REACTANTS
PRODUCTS
Scientists continued…
• Priestly
– Joseph Priestly (1733 – 1804)
Priestly was a Unitarian minister and
chemist. He did the following experiments:
– Summary:
– burning candle + bell jar → candle goes out +
add a mint plant → candle can be relit
– mouse + bell jar → dead mouse + add a mint
plant → mouse lives
For the visual learner
Questions
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Why did the candle burn out when placed under bell
jar?
Why could the candle be relit after allowing it growth
with a mint plant?
Why does a mouse die when it is placed under a bell
jar?
Why was the mouse able to survive when placed in the
jar with a mint plant?
Assuming a supply of water was available to both mint
plant and mouse; could the mouse and plant survive
indefinitely under the jar? Explain.
And yet…one more scientist
• Ingenhousz
– Finds that aquatic plants produce oxygen
bubbles in the light but not in the dark.
– Concludes that plants need SUNLIGHT to
produce OXYGEN
Light and Pigment
• Pigment is light absorbing material
– Chlorophyll
– 2 types of chlorophyll
• Chlorophyll a
• Chlorophyll b
• Chlorophyll absorbs light in the red and blue
regions
• WHY are plants green?
• Other plants contain different pigments to absorb
other parts of the spectrum…ex. carotene
8.3 Rxns of Photosynthesis
• Photosynthesis takes place in the
chloroplast.
Thylakoid
• Contains photosynthetic membranes
– Photosystems 1 and 2
Grana
• Stack of Thylakoids
2 Stages of Photosynthesis
• 1. Light Dependent Reaction
• Energy is captured to make storing compounds.
• Occurs inside the photosynthetic membrane
• Thylakoid membrane
• 2. Light Independent Reaction
•Does not require light directly
•Can occur in the light
•Uses stored energy from Light Rxn to make glucose in
the absence of light.
•Occurs outside the photosynthetic membrane
•Stroma
Light Dependent Rxn
• 4 processes
– 1. Light Absorption- photosystems capture light in
membrane
– 2. Electron Transport- NADP+ (enzyme carrier that
makes NADPH) NADPH helps build molecules in the
cell.
– 3. O2 Production- takes electrons from H2O forms O2
gas (released into the air)
– 4. ATP Formation- H2O splits, inside the + charges
collide with the – charges outside. Produces energy
to attach P+ADP=ATP.
Light Independent Rxn
(Calvin Cycle or Dark Rxn)
• Calvin Cycle uses 6 molecules of CO2 to
make a single 6-carbon sugar
• Plants use the sugar to make more
complex carbs like starches and cellulose.
• Uses ATP and NADPH from Light Rxn to
carry on Dark Rxn.
Factors affecting Photosynthesis
• Shortage of water
• Temperature
• Intensity or amount of light
Plants
• Multicellular eukaryotes
• Carry out photosynthesis using green
pigments…chlorophyll a & b
What is the advantage of two different
chlorophylls?
What do plants need to survive?
• Water, carbon dioxide, sunlight
How plants get nutrients
• Xylem- vascular tissue that carries water UP
from the roots to every part of the plant. (xy-hi)
• Phloem- vascular tissue responsible for
transport of nutrients and the carbs produced by
photosynthesis. (ploe-low)
Classification
• Gymnosperms-cone bearing
– Most common are: spruce, pine, firs, cedars,
evergreens.
Reproduction of Gymnosperms
• Female-actual cone
• Male-pollen cones
Classification
• Angiosperm- flowering plants (flowers or
fruit bearing)
Reproduction of Angiosperms
Important Terms
• Annuals- plant yearly
• Biennials- 2 years
• Perennials- through the years