Chapter 10 Photosynthesis - Biolympiads

[Pages:72]Chapter 10 Photosynthesis

Photosynthesis

? Process by which plants use light energy to make food.

? A reduction process that makes complex organic molecules from simple molecules.

Ps General Equation

6 CO2 + 6 H2O ---> C6H12O6 + 6 O2

Requires: Chlorophyll Light

Early Question

? Does the Oxygen in sugar come from the CO2 or from the H2O ?

? Model: CO2 + 2 H2O ----> CH2O + O2

Proof

? Used 18O as a tracer. CO2 + 2 H2O ----> CH2O + O2 CO2 + 2 H2O ----> CH2O + O2 Both experiments confirm that water is split. ? O2 is a waste product of Ps that altered life

on earth.

Ps: a redox process

? Hydrogens are added to Carbons. ? Water is a source for the Hydrogens. ? Complex covalent bonds are made.

Ps

? Has two chemical reactions: 1. Light Reaction 2. Calvin Cycle Names are from "light" as a requirement, not

where or when they occur.

Light

? A form of electromagnetic radiation. ? Visible light has the right energy for use in Ps.

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