Chapter 7 - Plant Phys

Photosynthesis

Process converting light energy into chemical energy.

Light Reactions

Initial phase of photosynthesis using light energy.

Chloroplasts

Organelles where photosynthesis occurs in plants.

Photosystems

Complexes of proteins and pigments for light absorption.

Electron Transport

Movement of electrons through proteins in thylakoid membrane.

ATP Synthesis

Production of ATP using energy from light reactions.

Electromagnetic Radiation

Energy waves including visible light and others.

Visible Light

Part of EM spectrum visible to the human eye.

Wavelength

Distance between successive wave crests.

Frequency

Number of wave crests passing a point per second.

Photon

Quantum of light, exhibiting particle-like properties.

Planck's Constant

Value of h = 6.62 x 10^-34 J s.

Energy of Photon

E = hn, where h is Planck's constant.

Blue Light Energy

E = 4.56 x 10^-19 J for 435 nm.

Red Light Energy

E = 3.01 x 10^-19 J for 660 nm.

Einstein

Energy of 1 mole of photons.

Solar Output

Distribution of solar energy: UV, visible, IR.

Ozone Layer

Blocks most UV radiation below 300 nm.

Chlorophyll

Primary pigment in plants for light absorption.

Chl a

Essential chlorophyll type found in all higher plants.

Chl b

Accessory chlorophyll in higher plants and green algae.

Carotenoids

Pigments that absorb light and protect from damage.

Absorption Spectrum

Range of wavelengths absorbed by a pigment.

Action Spectrum

Response of photosynthesis vs. wavelength.

Light-Harvesting Complex

Group of pigments capturing light energy.

Reaction Center

Special chlorophyll molecule where energy transfer occurs.

Energy Transfer

Process of passing energy between pigment molecules.

Quantum Yield

Efficiency of converting absorbed light to chemical energy.

Palisade Cells

Leaf cells maximizing light absorption with chloroplasts.

Photosynthesis Equation

6CO2 + 12H2O + hn → C6H12O6 + 6O2.

Hill Reaction

Light-driven water splitting producing oxygen.

Red Drop Effect

Decrease in photosynthesis efficiency with far-red light.

Photosystem I

Absorbs light at 700 nm, produces NADPH.

Photosystem II

Absorbs light at 680 nm, oxidizes water.

Z Scheme

Model of electron transport in photosynthesis.

Thylakoids

Membrane structures in chloroplasts where light reactions occur.

Cytochrome Complex

Protein complex involved in electron transport.

Plastocyanin

Copper-containing protein transferring electrons to PSI.

Cyclic Electron Flow

Electron flow only through PSI, producing ATP.

Noncyclic Electron Flow

Electron flow from H2O to NADPH, involving both photosystems.

Photophosphorylation

ATP production driven by light energy.

Proton Motive Force

Energy generated by H+ gradient across membranes.

ATP Synthase

Enzyme synthesizing ATP from ADP and inorganic phosphate.

Electron Transfer

Movement of electrons through the photosynthetic pathway.

Oxygen-Evolving Complex

Enzyme complex that splits water to release oxygen.

FRET

Fluorescence resonance energy transfer in light harvesting.

Chlorophyll Structure

Porphyrin head and phytol tail components.

Accessory Pigment

Pigment aiding in light absorption and protection.

Light Guide Effect

Mechanism enhancing light capture in leaves.

Sieve Effect

Arrangement of cells optimizing light penetration.

Energy Funneling

Process ensuring energy reaches the reaction center.

Fluorescence

Re-emission of absorbed light, often as heat.

Thermal Energy

Energy lost as heat during light absorption.

Photochemistry

Chemical reactions driven by absorbed light energy.