Chapter 9 - Photosynthesis



SBI4U- Photosynthesis

2 Sets of Reactions in Photosynthesis

Light-Dependent Reactions

-The light-dependent reactions require _______

-These reactions occur in the ________________________

-They produce _________ and __________ which are needed

to produce glucose in the light-independent reactions

Light-Independent Reactions

-Light-independent reactions occur in stroma of the

chloroplast in light or dark conditions.

-They function to reduce CO2 to glucose.

How does a Plant turn light from the sun into useable Energy?

Photosynthetic pigments in the membrane of the thylakoid form a unit called an __________________________

A ___________________________ within the antenna absorbs a photon of light energy. The energy from that pigment molecule is passed to neighboring pigment molecules and eventually makes its way to pigment molecule called the ___________________________

The reaction center molecule becomes excited (energized), it loses an electron to an electron acceptor.

Photosystems

The antenna and the reaction center are called a _______________

There are two kinds of photosystems in plants:

13 Photosystem I: Contains a __________________ reaction center that absorbs ____________ light

14 Photosystem II: Contains a ______________ reaction center that absorbs ____________ light

The ________________________________________________ from the reaction center.

16 As a result of gaining an electron (reduction), the electron acceptor becomes a high-energy molecule.

17 Recall that oxidation is the loss of an electron and the ____________________. Reduction is the gain of an electron and energy. Energy is transferred with the electron.

Light Dependent Reactions

1. Pigments in Photosystem II absorb a _________________ of energy from __________

2. Energy is passed from these pigments to the ____________________________ (P680)

3. The reaction center passes the electron to the _________________________________

4. The electron carrier ________________ when it gains an electron and uses this energy to ________________________________________________

5. The electron is then passed to a second electron carrier

6. The second electron carrier also uses its energy to pump H+ ions into the thylakoid lumen

7. The electron is then passed to a third electron carrier

8. The third electron carrier also uses its energy to pump H+ ions into the thylakoid lumen

9. The H+ ions in the lumen want to get out! ____________________ pumps them into the ___________________, using the energy released to create __________ (This process is called chemiosmosis)

10. The electron is passed from the electron carrier to the _______________ complex in photosystem I

11. Pigments in Photosystem I gain energy from absorbing a photon of light and the energy is passed to the P700 reaction center

12. The excited electron from P700 is passed to an electron carrier

13. The electron is then passed to NADP+ (along with an H+ ion) to form a high energy NADPH molecule

14. The electron is then passed to __________________ (along with an H+ ion) to form a high energy NADPH molecule

15. The electron lost by Photosystem II needs to be replaced! Water is broken down to form 2 electrons (This reaction also produces Oxygen which will be released by the plant

SBI4U: Photosynthesis II

Light Independent Reaction- The Calvin Cycle

Purpose:

– To create _________________________ from _____________

– This reaction requires _______________________

– The energy required to power this reaction comes from _________ and _______________ created in the ___________________

Location:

– The __________________ of the plant cell

Calvin Cycle Terms:

1. CO2 Fixation: The bonding of ____________ to an ______________________ to make a larger molecule.

2. RuBP: A ______________ molecule found in the Calvin Cycle

3. RuBP Carboxylase: An ______________ that catalyzes the reaction between ________ and _____________

4. PGA: A _______________ molecule found in the Calvin Cycle

5. PGAL: A ________________ molecule found in the Calvin Cycle (2 PGALs join to make 1 __________________ molecule)

Steps of the Calvin Cycle:

CO2 binds to RuBP making a C6 molecule

The C6 molecule splits into 2 C3 compounds of PGA

The 2 molecules of PGA are reduced to PGAL

38 This reaction requires energy (the ATP and NADPH formed in the light reactions are used!)

2 molecules of PGAL are used to form photosynthesis

The remaining 10 molecules of PGAL are re-arranged into 6 molecules of RuBP

41 This reaction requires energy (the ATP and NADPH formed in the light reactions are used!)

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Overview of Reactions in Photosynthesis:

6CO2 + 6H2O + Energy ( C6H12O6 + 6O2

Homework: Draw your own diagrams of the electron transport chain!

-Make sure to label the 15 steps!

-You also must label (at least) the following components: thylakoid lumen, thylakoid membrane, stroma, electron carrier, Photosystem I and II, P700 & P680 reaction centers, ATP Synthase, pigments, antenna

thylakoid lumen

[pic]

Carbon Fixation

The Calvin Cycle

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