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Lesson Overview Lesson Overview Photosynthesis: An Overview Photosynthesis: An Overview Lesson Lesson Overview Overview 8.2 8.2 Photosynthesis : An Overview

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Page 1: Lesson Overview Lesson Overview Photosynthesis: An Overview Lesson Overview 8.2 Photosynthesis: An Overview PhotosynthesisOverviewPhotosynthesisOverview

Lesson OverviewLesson Overview Photosynthesis: An OverviewPhotosynthesis: An Overview

Lesson OverviewLesson Overview8.2 8.2 Photosynthesis:

An Overview

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Lesson OverviewLesson Overview Photosynthesis: An OverviewPhotosynthesis: An Overview

Light

Energy from the sun travels to Earth in the form of light.

Sunlight is a mixture of different wavelengths, many of which are visible to our eyes and make up the visible spectrum.

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Lesson OverviewLesson Overview Photosynthesis: An OverviewPhotosynthesis: An Overview

Pigments

Plants gather the sun’s energy with light-absorbing molecules called pigments.

The plants’ principal pigment is chlorophyll.

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Lesson OverviewLesson Overview Photosynthesis: An OverviewPhotosynthesis: An Overview

Pigments

Page 5: Lesson Overview Lesson Overview Photosynthesis: An Overview Lesson Overview 8.2 Photosynthesis: An Overview PhotosynthesisOverviewPhotosynthesisOverview

Lesson OverviewLesson Overview Photosynthesis: An OverviewPhotosynthesis: An Overview

ChloroplastsChloroplasts contain saclike photosynthetic membranes called thylakoids, which are interconnected and arranged in stacks known as grana.

The fluid portion outside of the thylakoids is known as the stroma.

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Energy Collection

When chlorophyll absorbs light, a large fraction of the light energy is transferred to electrons. These high-energy electrons make photosynthesis work.

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High-Energy ElectronsThe high-energy electrons produced by chlorophyll are highly reactive and

require a special “carrier.”

Think of a high-energy electron as being similar to a hot potato. If you wanted to move the potato from one place to another, you would use an oven mitt —a carrier—to transport it.

Plants use electron carriers to transport high-energy electrons from chlorophyll to other molecules.

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High-Energy ElectronsNADP+ (nicotinamide adenine dinucleotide phosphate) is a carrier molecule.

NADP+ accepts and holds two high-energy electrons, along with a hydrogen ion (H+). In this way, it is converted into NADPH.

The NADPH can then carry the high-energy electrons to chemical reactions elsewhere in the cell.

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An Overview of PhotosynthesisPhotosynthesis uses the energy of sunlight to convert water and carbon dioxide into high-energy sugars and oxygen.

In symbols:

6 CO2 + 6 H2O C6H12O6 + 6 O2

In words:

Carbon dioxide + Water Sugars + Oxygen

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An Overview of Photosynthesis

Plants use the sugars generated by photosynthesis to produce complex carbohydrates such as starches, and to provide energy for the synthesis of other compounds, including proteins and lipids.

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Light-Dependent Reactions

Photosynthesis involves two sets of reactions.

The first set of reactions is known as the light-dependent reactions because they require the direct involvement of light and light-absorbing pigments.

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Light-Dependent ReactionsThe light-dependent reactions use energy from sunlight to produce ATP and NADPH.

These reactions take place within the thylakoid membranes of the chloroplast.

Water is required as a source of electrons and hydrogen ions. Oxygen is released as a byproduct.

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Light-Independent ReactionsDuring light-independent reactions, ATP and NADPH molecules produced in the light-dependent reactions are used to produce high-energy sugars from carbon dioxide.

No light is required to power the light-independent reactions.

The light-independent reactions take place outside the thylakoids, in the stroma.

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Lesson OverviewLesson Overview Photosynthesis: An OverviewPhotosynthesis: An OverviewQuestions1. In the process of photosynthesis, plants convert the energy of sunlight into

chemical energy stored in the bonds of _________. Carbohydrates

2. Photosynthetic organisms capture energy from sunlight with ________. Pigment

3. The plant’s principal pigment is _______. Chlorophyll

4. Photosynthesis takes place in ___________. Chloroplasts

5. T or F - Chloroplasts contain an abundance of saclike photosynthetic membranes called thylakoids. TRUE

6. T or F - The fluid portion of the chloroplast, outside of the thylakoids, is known as the matirx. FALSE - STROMA

7. Raising the energy levels of electrons on the chlorophyll molecule, light energy can produce a steady supply of _______________electrons, which is what makes photosynthesis work. High Energy

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Questions8. An electron _________is a compound that can accept a pair of high-energy

electrons and transfer them, along with most of their energy, to another molecule.Carrier

9. NADP+ is converted to ______________as it accepts and transfers electrons to chemical reactions elsewhere in the cell.NADPH

10. What is the overall equation of photosynthesis?6CO2 + 6H2O + light C6H12O6 + 6O2

11. The light- ______________reactions produce ATP and NADPH from sunlight in the thylakoid membranes.Dependent

12. The light-______________t reaction in the stroma, sugars are created from carbon dioxide using the ATP and NAPH from the light-dependent reactions.Independent

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Photosynthesis REVIEW

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Photosynthesis REVIEW

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Photosynthesis REVIEW

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What is the equation for photosynthesis?