Bell Ringer

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Bell Ringer

• List 10 different methods of energy.

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Chapter 8

• Photosynthesis

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Energy and Life

• Plants and some other types of organisms are able
  to use light energy from the sun to produce food.
• Autotrophs Plants which are able to make their
  own food.
• Heterotrophs Obtain their energy from the food
  they consume.

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• Adenosine triphosphate One of the principle
  chemical compounds that cell use to store and
  release energy.
• ATP consists of adenine a five carbon sugar
  called ribose and three phosphate groups.
• The three phosphate groups are the key to ATPs
  ability to store and release energy.

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ATP
Section 8-1
Adenine
Ribose
3 Phosphate groups
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• The characteristics of ATP make it exceptionally
  useful as the basic energy source of all cells.

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Photosynthesis an Overview

• Photosynthesis plants use the energy of
  sunlight to covert water and carbon dioxide into
  high energy carbohydrates sugars and starches
  and oxygen a waste product.

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Investigating Photosynthesis

• Van Helmonts experiment In 1643 Jan van
  Helmont devised an experiment to find if plants
  grew by taking material out of soil.
• He determined the mass of a pot of dry soil and a
  small seedling.
• He planted the seedling in the pot of soil.
• He watered it regularly.
• At the end of five years the seedling had grown
  into a small tree, and had gained 75 kg.
• The mass of the soil had remained unchanged.
• He concluded that the mass came from the water

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• In 1771 Joseph Priestly took a candle, placed a
  glass jar over it, and watched as the flame
  gradually went out.
• He concluded that something in the air kept the
  flame lit.
• Priestly then placed a plant in the jar with the
  candle under the jar the candle stayed lit for a
  few days.
• He concluded that the mint created a substance
  for the candle to stay lit.

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• Jan Ingenhouosz repeated both van Helmonts and
  Priestleys experiments and he concluded that
  these results occurred when the plant was exposed
  to light.
• Other scientists then discovered that in the
  presence of light, plants transform carbon
  dioxide and water into carbohydrates and they
  then release oxygen.

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• The formula for photosynthesis is a follows
• 6CO2 6H2O C6H12O6 6O2
• Carbon Dioxide water yields glucose and oxygen
• Photosynthesis uses the energy of sunlight to
  convert water and carbon dioxide into high energy
  sugars and oxygen.

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Concept Map
Section 8-3
Photosynthesis
includes
takes place in
uses
use
take place in
to produce
to produce
of
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The Reactions of Photosynthesis

• The leaf is the site of photosynthesis

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• Within the leaf are chloroplast which contain sac
  like photosynthetic membranes called thylakoids.

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Chloroplasts

• Thylakoids are arranged in stacks called grana.
• Proteins in the thylakoid membrane organize
  chlorophyll and other pigments into clusters
  known as photosystems.
• These photosystems are the light collecting units
  of the chloroplasts.

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• The reactions of photosynthesis is in two parts.
• 1. Light Dependent Reactions takes place in the
  thylakoid membranes
• 2. The Calvin Cycle Takes place in the stroma
  or the area outside the thylakoid membrane

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Electron Carriers

• When sunlight strikes the chlorophyll, the
  electrons gain energy.
• The high energy electrons require a special
  carrier.
• The electron carriers transport high energy
  electrons to transport high energy electrons from
  chlorophyll to other molecules.

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• One of the electron carriers in photosynthesis is
  NADP (nicotinamide adenine dinucleotide)
• NADP accepts and holds two high energy electrons
  along with a hydrogen ion (H)
• This converts NADP to NADPH is one way that some
  of the energy from sunlight can be trapped into
  chemical form.
• The NADPH and then carry high energy electrons
  produced in light absorption in chlorophyll to
  chemical reactions elsewhere in the cell.

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Figure 8-7 Photosynthesis An Overview
Section 8-3
Chloroplast
Chloroplast
NADP
ADP P
Light- Dependent Reactions
Calvin Cycle
ATP
NADPH
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Light Dependent Reactions

• Light dependent reactions require light
• Light dependent reactions produce oxygen gas and
  convert ADP and NADP into energy carriers ATP
  and NADPH.

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Calvin Cycle

• ATP and NADPH are formed by light dependent
  reactions and contain a tremendous amount of
  chemical energy.
• The Calvin Cycle uses ATP and NADPH from the
  light dependent reactions to produce high energy
  sugars.
• The Calvin Cycle was named after American
  scientist Melvin Calvin

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Factors Affecting Photosynthesis

• 1. Amount of water a shortage of water can slow
  or even stop photosynthesis.
• 2. Temperature Photosynthesis depends on
  enzymes that function best between 0C and 35C.
• 3. Intensity of light also affects the rate at
  which photosynthesis occurs.

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• The Calvin Cycle does not require light.
• The Calvin Cycle uses six molecules of carbon
  dioxide to produce and single carbon molecule
  sugar, which is glucose.
• The plant uses the glucose to meet its energy
  needs and to build more complex macromolecules
  such as cellulose that it needs for growth and
  development.
• Other organisms that eat the plants, they can
  also use the energy stored in carbohydrates.

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Figure 8-11 Calvin Cycle
Section 8-3
CO2 Enters the Cycle
Energy Input
ChloropIast
5-Carbon Molecules Regenerated
6-Carbon Sugar Produced
Sugars and other compounds
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