Photosynthesis Biology (IB HL)

Photosynthesis

light to chemical energy as carbon compounds

Ecosystem

a community of living organisms interacting with nonliving organisms, interacting as a system

Photolysis

light energy absorbed by chlorophyll, splitting water into hydrogen ions and oxygen gas.

Chromatography

a strategy used to separate the pigments found on a leaf.

Pigments

chemical substances produced by living organisms, giving them their color through selective absorption of light wavelengths

Chlorophyll

the main light-absorbing pigment in leaves. Absorbs blue and red light best, reflects green.

Accessory Pigments

absorb different wavelengths of light than chlorophyll, giving leaves a red or orange color (carotene and xanthophyll)

Rf Values

measure of how far a pigment travels down a piece of paper in chromatography.

Absorption Spectrum

a graph showing the range of light wavelengths absorbed by a pigment (usually chlorophyll)

Action Spectrum

graph showing the overall rate of photosynthesis at each wavelength

Free-Air Carbon Dioxide Enrichment Experiments (FACE)

used to investigate the effect of carbon dioxide on plants on larger scales

Field Experiment

research studies manipulating variables in real-world settings

Independent Variable

variable x whose variation doesn’t depend on something

Dependent Variable

variable y whose value depends on another data set or set of information

Control Variable

any factor that a researcher intentionally keeps the same to prevent it from influencing results.

Light Dependent Reactions

reactions in photosynthesis that need light to function. Includes photoactivation, photolysis, the ETC, chemiosmosis, ATP synthesis, and reduction of NADP to NADPH

Light-Independent Reactions

photosynthesis reactions that can happen without light, including the Calvin cycle.

Calvin Cycle

carbon dioxide is fixed (CO2 attaches to RuBP) and converted into organic molecules, primarily glucose, utilizing the energy from ATP to NADPH.

Electron Transport Chain

a series of molecules within the thylakoid membrane that transfer electrons from one to another in a series of oxidation-reduction reactions.

Chemiosmosis

facilitated diffusion of protons across the membrane through ATP synthase

Photosystems

an array of chlorophyll molecules and accessory pigments located within membranes

Photoactivation

energy from light being used to excite electrons in a chlorophyll pigment so electrons can move through ETC.

Photolysis

breaking apart a water molecule, into protons (H) and oxygen (O) used as waste.

Chloroplast

molecule facilitating photosynthesis.

Stroma

area outside of the thylakoid membrane

Thylakoid Membrane

has ETC and ATP synthase for phosphorylation

Thylakoid Space

stacked pancakes inside of chlorophlast.

Phosphorylation

adding of a phosphate group to ADP to form ATP using energy derived from light

Cyclic Photophosphorylation

electrons being recycled back to the photosystem, generating ATP

Non-Cyclic Photophosphorylation

flow of electrons from water to NADP+ during photosynthesis

Oxidation

loss of electrons, usually with water

Reduction

gain of electrons

NADP

can be used as an electron acceptor and carrier in photosynthesis.

NADPH

redacted version of NADP, energy carrying molecule.

ATP Synthase

protons moving down ETC gradient create ATP

Carbon Fixation

adding carbon from an inorganic compound (co2) to an organic compound

Rubisco

speeds up the rate of the first step of carbon fixation in photosynthesis (RUBP)

RuBP

primary CO2 acceptor in the Calvin Cycle.

Glycerate 3-phosphate

main product of the Calvin cycle.

Triose Phosphate

converted from G3P using NADPH and ATP