Photosynthesis LIght Reaction

Photosynthesis

The process that converts solar energy into chemical energy.

6CO2 + 6H2O + solar energy → C6H12O6 + 6O2

Autotrophs

Producers of the biosphere that produce organic molecules from carbon dioxide, water, and sunlight.

Heterotrophs

Consumers that obtain their organic material from other organisms.

Chloroplasts

Organelles present in plant cells, responsible for photosynthesis, likely evolved from photosynthetic bacteria.

Pores on the underside of leaves that allow gases like carbon dioxide and oxygen to enter and exit.

Stomata

Connected sacs in the chloroplast that compose a third membrane system and contain chlorophyll.

Thylakoids

Stacks of thylakoids in the chloroplast.

Grana

Endosymbiotic theory

The theory that explains the origin of eukaryotic cells, proposing that chloroplasts evolved from engulfed photosynthetic bacteria.

Light Reaction

The first stage of photosynthesis where solar energy is converted to chemical energy (ATP and NADPH) and oxygen is released.

Calvin Cycle

The second stage of photosynthesis that does not require light, using ATP and NADPH to synthesize sugars from carbon dioxide.

An electron carrier produced in the light reactions that provides reducing power for the Calvin cycle.

NADPH

A high-energy molecule produced during both the light reactions and the Calvin cycle, used for energy in cellular processes.

ATP

The process of light absorption by chlorophyll that elevates electrons to a higher energy state.

Photoexcitation

Photosystem II

The first photosystem in the light reactions, best at absorbing light at 680 nm, associated with the release of oxygen.

Cyclic electron flow

A type of electron flow in the light reaction that involves only photosystem I, producing ATP but not NADPH or oxygen.

Non-cyclic photophosphorylation

The linear electron flow involving both photosystems, producing ATP, NADPH, and oxygen.

The main photosynthetic pigment responsible for absorbing light, primarily in the blue and red wavelengths.

Chlorophyll

Electromagnetic Spectrum

The range of all types of electromagnetic radiation, including visible light, ultraviolet, and infrared.

Absorption Spectrum

A graph showing how a pigment absorbs light at different wavelengths.

Action Spectrum

A graph depicting the relative effectiveness of different wavelengths of light in driving photosynthesis.

Chemiosmosis

The process of generating ATP through the movement of protons across a membrane.

Cells that surround the stomata and regulate their opening and closing.

Guard cells

The main product of the Calvin cycle, formed from carbon dioxide.

Glucose

A byproduct of the light reactions of photosynthesis, released into the atmosphere.

Oxygen

Proton gradient

The difference in concentration of protons across a membrane, driving ATP synthesis.

Define the Calvin Cycle.

a light-independent stage of photosynthesis where ATP and NADPH are used to transform carbon dioxide into glucose.

Identify the location of the Calvin Cycle.

in the stroma of chloroplasts.

What are the key stages in the Calvin Cycle?

carbon fixation, reduction, and regeneration of ribulose bisphosphate (RuBP).

Explain the function of RuBP in the Calvin Cycle.

acts as the carbon dioxide acceptor in the Calvin Cycle.

What is the main product generated by the Calvin Cycle?

glucose, formed from carbon dioxide.

Chlorophyll a (Chl a)

The main photosynthetic pigment that participates directly in photosynthesis, absorbing predominantly blue-violet and red light.

Chlorophyll b (Chl b)

An accessory pigment that assists in capturing light energy for photosynthesis, absorbing blue and red-orange light.

What is oxidized and what is reduced in photosynthesis

In water (H2O) is oxidized to release oxygen (O2), while carbon dioxide (CO2) is reduced to form glucose (C6H12O6).

Photosystem 1

The second photosystem that operates after Photosystem II, primarily involved in producing NADPH during the light reactions.