Show Menu

Photos­ynt­hesis equation

6CO2+1­2H2­O+Light Energy­→C6­H12O6+ 6O2+6H2O

Process That Feeds The Biosphere

Photos­ynt­hes­is-­process that converts solar energy into chemical energy
Autotr­oph­-su­stain themselves without eating anything from other organisms
Photoa­uto­tro­ph-­obtain their organic material from other organisms

Converting light energy to chemical energy of food

Chloro­pla­sts-the sites of PS in plants
Leaves­-major locations of PS
Chloro­phy­ll-­green pigment within chloro­plasts
Stomat­a-m­icr­oscopic pores CO2 enters and O2 exits through the leaf
Mesoph­yll­-in­terior tissue of leaf
Thylak­oid­s-c­onn­ected sacs in the chloro­plast
Stroma-a dense fluid chloro­plasts contain

Photos­ynt­hetic Pigments

Absorption spectr­um-­graph plotting a pigment's light absorption versus wavelength
Action spectr­um-­pro­files the relative effect­iveness of different wavele­ngths of radiation in driving a process
Chloro­phyll A-main photos­ynt­hetic pigment
Chloro­phyll B-acce­ssory pigments that broadens the spectrum used for PS
Carote­noi­ds-­acc­essory pigments that absorb excess light that would damage chloro­phyll

The Splitting Of Water

Chloro­plasts split H2O into hydrogen and oxygen, incorp­orating the electrons of hydrogen into sugar molecules

Photos­ynt­hesis as a redox process

H2O is oxidized and CO2 is reduced

The light reactions (in the thylak­oids)

Split H2O
Release O2
Reduce NADP+ to NADPH
Generate ATP from ADP by Phosph­ory­lation

Calvin Cycle (in the stroma)

Forms sugar from CO2, using ATP and NADPH
Begins with carbon fixation, incorp­orating CO2 into organic molecules

Light to Chemical Energy

Thylakoids transform light energy into chemical energy using ATP and NADPH

Linear electron flow

Linear electron flow-p­rimary pathway, involves both photos­ystems and produces ATP and NADPH using light energy

A Photos­ystem

Photos­ystem- reacti­on-­center complex surrounded by light harvesting complexes
Primary electron accept­or-­rea­ction center accepts an electron from chloro­phyll A
Photos­ystem II (functions first)­-best at absorbing wavelength of 680 nm
Photos­ystem I (functions second­)-best at absorbing wavelength of 700 nm

C3 Plants

Most common and the most efficient at photos­ynt­hesis in cool, wet climates

C4 Plants

Minimize photor­esp­iration by incorp­orating CO2 into 4 carbon compounds in mesophyll cells
Requires PEP carbox­ylase (has a higher affinity for CO2 than O2)

CAM Plants

Open stomata at night, incorp­orating CO2 into organic acids and used in the calvin cycle

Importance of Photos­ynt­hesis

Energy entering chloro­plasts as sunlight gets stored as chemical energy in organic compounds
Plants store excess sugar as starch in structures such as roots, tubers, seeds, fruits
Produces O2 in our atmosphere

Importance of Photos­ynt­hesis

Energy entering chloro­plasts as sunlight gets stored as chemical energy in organic compounds

Cyclic Electron Flow

Uses only PS 1 and produces ATP but not NADPH
Generates surplus ATP, satisfying higher demand for calvin cycle
May protect cells from light induced damage

The Nature of Sunlight

Light is a form of electr­oma­gnetic energy that travels in rhythmic waves
Wavele­ngt­h-d­istance between crests of waves
Wavelength determines the type of electr­oma­gnetic energy
Electr­oma­gnetic Spectrum- entire range of electr­oma­gnetic energy or radiation
Visible light-­wav­ele­ngths that produce colors we can see
Photons- discrete particles light consists of


No comments yet. Add yours below!

Add a Comment

Your Comment

Please enter your name.

    Please enter your email address

      Please enter your Comment.

          Related Cheat Sheets

          AP Biology Unit 3: Energy and Metabolism Cheat Sheet