Biology Chapter 8 - Photosynthesis

Front 1

Photosynthesis

Back 1

- energy in light is captured and used to make carbs

- CO2 is reduced

- H2O is oxidized

- energy from light drives reaction

Front 2

Heterotroph

Back 2

must eat food to sustain life

Front 3

Autotroph

Back 3

makes organic molecules from inorganic sources

Front 4

Photoautotroph

Back 4

light used as a source of energy

Front 5

Chloroplast

Back 5

- organelle in which photosynthesis occurs

- Co2 enters and O2 exits leaf through pores called stomata

Front 6

Chlorophyll

Back 6

green, photosynthetic pigment

Front 7

Thykaloid membrane

Back 7

contains plant pigments

Front 8

Thykaloids

Back 8

flattened, fluid-filled tubules

Front 9

Granum

Back 9

stack of thykaloids

Front 10

Stroma

Back 10

region between thykaloid and inner membranes

Front 11

About Photosynthetic Pigments

Back 11

-having different pigments allows plants to absorb light at many different wavelengths

- after electrons absorb energy the become excited and unstable

- excited electrons are transferred to a more stable molecule

Front 12

Photosynthetic Pigments

Back 12

- chlorophyll

- carotenoids

Front 13

Chlorophyll

Back 13

- Chlorophyll (a) (primary photosynthetic pigment)

- Chlorophyll (b)

- both found in green plants and algae

Front 14

Carotenoids

Back 14

- yellow, red, orange, etc. pigments in leaves

- masked by the amount of chlorophyll in warmer seasons

- lower temp = less chlorophyll and more carotenoids showing

- different pigments give a larger range of light absorption

Front 15

Stages of Photosynthesis

Back 15

- Light Reactions

- Noncyclic Electron Flow

- Cyclic Electron Flow

Front 16

Light Reactions

Back 16

- pigments get energy from sunlight

- ATP, NADH, and O2 are generated

- oxidizes water

Front 17

Photosystem

Back 17

light-energy harvesting system

- Photosystem I (PSI)

- Photosystem II (PSII)

- light excites pigments in both of these

Front 18

Photosystem II

Back 18

- 1st step in photosynthesis

- excited electrons travel from here to PSI

- electrons pass thru ETC and release energy

Front 19

Photosystem I

Back 19

- occurs after PSII

- primary NADPH maker

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How is H+ Gradient Made?

Back 20

- increase [H+] in thykaloid lumen by splitting of water

- or increase [H+] by ETC pumping H+ into lumen

- or decrease [H+] in stroma from formation of NADPH

Front 21

Products of Light Reactions

Back 21

- Oxygen made in thykaloid lumen by oxidation of H2O

- NADPH made in stroma from electrons that are boosted in PSI

- ATP made in stroma

Front 22

Noncyclic Electron Flow

Back 22

- light excites electrons in pigment molecules

- excited electrons pass linearly from PSII to PSI

- NADP+ reducted to NADPH

Front 23

Cyclic Electron Flow

Back 23

- makes only ATP

- PSI electrons excited, release energy and return to PSI

Front 24

Steps of the Clavin Cycle

Back 24

- Carbon Fixation

- Reduction Phase and Carb Synthesis

- Regeneration of RuBP

Front 25

Calvin Cycle

Back 25

- uses more ATP than NADPH

- CO2 incorporated into carbs

- requires A LOT of energy.

- reduction by NADPH

Front 26

Carbon Fixation

Back 26

- CO2 incorporated into RubP (5-carbon sugar)

- requires rubisco

- product: 6-carbon molecule that splits into two 3-PG

Front 27

Reduction and Carbs Synthesis Phase

Back 27

-ATP and NADPH are used to convert 3PG to G3P

- 12 G3P molecules made in this step

Front 28

Regeneration of RuBP

Back 28

- keeps Calvin Cycle running

Front 29

Environmental Factors Affecting the Calvin Cycle

Back 29

- light intensity

- temperature

- water availability

Front 30

C4 Plants

Back 30

- have mechanism to minimize photorespiration

- C4 plants make oxalacetate (4-carbon molecule)

- leaves have two-cell layer organization

Front 31

C3 vs. C4

Back 31

- warm and dry climates: C4 plants

- cooler climates: C3 plants use les energy to fix CO2

- 90% of plants are C3