Biology Unit 2: Cell Energy Vocabulary

A complete set of vocabulary flashcards covering photosynthesis, cellular respiration, and energy production for the Biology Unit 2 Quiz.

carbonic acid

A weak acid formed when carbon dioxide dissolves in water, often monitored in cellular respiration experiments.

pH

A measure of the acidity or basicity of an aqueous solution, determined by the concentration of hydrogen ions ($H^+$).

wavelength

The distance between consecutive crests or peaks of a wave, which determines the color and energy of light waves.

electromagnetic spectrum

The full range of all types of electromagnetic radiation, organized by wavelength or frequency, which includes visible light.

visible light

The segment of the electromagnetic spectrum detectable by the human eye that provides the light energy absorbed to drive photosynthesis.

Enzyme

A biological protein catalyst that accelerates metabolic chemical reactions by lowering the activation energy.

photopigments

Light-absorbing molecules within photosynthetic cells, such as chlorophyll, that absorb specific wavelengths of light.

chloroplasts

Membrane-bound organelles found in plant and algal cells where photosynthesis takes place.

mitochondria

Membrane-bound organelles where cellular respiration occurs to generate ATP for cellular processes.

vacuole

A membrane-bound cell organelle used for storing nutrients, wastes, and water, helping support cell structure.

reflected

Light waves that bounce off a surface or pigment rather than being absorbed, determining the perceived color of an object.

transmitted

Light waves that pass completely through an object or medium without being absorbed.

absorbed

Light energy that is captured by photopigments to be transformed into chemical energy during photosynthesis.

photosynthesis

The process by which autotrophic cells capture light energy and convert it into chemical energy stored in glucose.

Light-dependent reactions

The first stage of photosynthesis occurring in thylakoid membranes that uses light energy and water to generate ATP, NADPH, and oxygen.

Calvin cycle (light-independent reaction)

The phase of photosynthesis taking place in the stroma that utilizes ATP and NADPH to synthesize glucose from carbon dioxide.

glucose

A six-carbon simple sugar ($C_6H_{12}O_6$) produced by photosynthesis and broken down during cellular respiration to yield energy.

photon

A discrete packet or fundamental unit of light energy absorbed by pigment molecules.

photolysis

The process of splitting water molecules using light energy into electrons, protons, and oxygen during the light-dependent reactions.

NADPH

An electron carrier molecule formed in the light-dependent reactions that provides high-energy electrons and hydrogen to power the Calvin cycle.

cellular respiration

The process of breaking down chemical bonds in organic molecules like glucose to generate ATP energy for cellular reactions.

electron transport chain

A sequence of membrane-embedded protein complexes that transfer electrons to create a proton gradient across a membrane.

protons

Positively charged hydrogen ions ($H^+$) that are concentrated across a membrane to establish an electrochemical gradient for ATP synthesis.

chemiosmosis

The movement of protons across a selectively permeable membrane down their electrochemical gradient to drive the synthesis of ATP.

ATP synthase

A membrane-bound enzyme complex that uses the flow of protons across a membrane to attach a phosphate group to ADP, synthesizing ATP.

ADP

Adenosine diphosphate, a low-energy molecule composed of adenine, ribose, and two phosphate groups that is phosphorylated to form ATP.

ATP

Adenosine triphosphate, the cellular energy currency that supplies energy for chemical reactions in cells.

thylakoids

Flattened, disk-like membrane compartments inside chloroplasts where the light-dependent reactions take place.

stroma

The fluid-filled space within chloroplasts that surrounds the thylakoids and serves as the site for the Calvin cycle.