Photosynthesis and Plant Physiology

Comprehensive vocabulary flashcards covering the process of photosynthesis, including pigments, leaf anatomy, chloroplast structure, and the light-dependent and light-independent cycles.

Photosynthesis

The process by which plants, some bacteria, and some protistans use energy from sunlight to produce glucose from carbon dioxide and water.

Chlorophyll

A complex green pigment molecule that converts sunlight energy into chemical energy, featuring a lipid-soluble hydrocarbon tail and a hydrophilic head with a magnesium ion.

Accessory Pigments

Pigments such as chlorophyll b, xanthophylls, and carotenoids that absorb light energy at wavelengths chlorophyll a does not.

Xylem Vessels

Specialized plant cells that transport water from the roots up to the leaves.

Stomata

Small openings on the leaf surface, flanked by guard cells, that allow gas exchange (CO2 and O2) but also result in water loss.

Cuticle

A protective waxy layer covering the leaf that prevents carbon dioxide and water from passing through.

Thylakoid

The structural unit of photosynthesis consisting of flattened sacs or vesicles containing photosynthetic chemicals.

Grana

Pancake-like stacks of thylakoids found within the chloroplast.

Stroma

The fluid-filled areas between the grana where the light-independent reactions (Calvin Cycle) occur.

Photoexcitation

The process where electrons in a chlorophyll molecule gain energy and move to higher energy levels upon absorbing light energy.

Photoionisation

The ionisation of a chlorophyll molecule when it absorbs enough energy to free an electron, leaving the molecule positively charged.

Photolysis

The light-dependent splitting of water molecules into oxygen, hydrogen ions, and free electrons.

Photosystem

A functional unit in the thylakoid membrane composed of a chlorophyll molecule, an electron acceptor, and an electron donor.

Z Scheme

A diagrammatic representation of the energy changes during the electron transfer process in the light-dependent reactions.

Chemiosmosis

The movement of H+ ions across a membrane down an electrochemical gradient, which drives the synthesis of ATP.

Cyclic Phosphorylation

A light-dependent process involving only Photosystem I that generates extra ATP without producing NADPH.

Carbon Fixation

The initial incorporation of carbon dioxide from the atmosphere into organic compounds.

Ribulose 1,5-biphosphate (RuBP)

A five-carbon sugar that reacts with carbon dioxide in the first step of the light-independent reactions.

Glycerate 3-phosphate (GP)

A three-carbon molecule formed by the breakdown of an unstable six-carbon intermediate during carbon fixation.

Glyceraldehyde 3-phosphate (GALP)

A three-carbon sugar (also known as PGAL) produced by the reduction of GP, used to form glucose or regenerate RuBP.

Limiting Factors

External factors such as light intensity, carbon dioxide concentration, and temperature that restrict the rate of photosynthesis.