AP Bio Unit 3

acetyl CoA

Intermediate step from pyruvate oxidation to the Krebs cycle, consisting of a two-carbon acetyl group attached to coenzyme A.

aerobic

Respiration that occurs in the presence of air.

alcohol fermentation

Anaerobic glycolysis that produces ethanol and carbon dioxide.

anaerobic

Process or activity that occurs without air.

cellular respiration

The process by which animal cells break down glucose to create ATP, including glycolysis, pyruvate oxidation, acetyl CoA formation, the Krebs cycle, and oxidative phosphorylation.

chemiosmosis

The process that uses energy from the electron transport chain to create an electrochemical proton gradient which drives ATP synthesis.

citric acid cycle/Krebs cycle

Cycle in which acetyl is fully oxidized, producing CO2, NADH, FADH2, and ATP.

electron transport chain

A series of protein complexes that transfer electrons derived from NADH and FADH2 to generate ATP.

facultative anaerobe

An organism that can perform aerobic respiration in the presence of oxygen and switch to anaerobic respiration without it.

fermentation

Anaerobic metabolic pathway that converts glucose into ATP.

glycolysis

The process of breaking down glucose into pyruvate, producing ATP and NADH.

lactic acid fermentation

An anaerobic metabolic pathway in animals that converts glucose into ATP and lactic acid.

NAD+

A reduced electron carrier used in all steps of cellular respiration.

oxidation

The loss of electrons.

oxidative phosphorylation

The process in which NADH and FADH2 donate electrons to the electron transport chain, generating large amounts of ATP.

oxidizing agent

A substance that donates electrons in a chemical reaction.

redox reaction

A chemical reaction that involves the transfer of electrons.

reducing agent

A substance that gains electrons in a chemical reaction.

reduction

The gain of electrons.

substrate-level phosphorylation

The production of ATP from ADP and a phosphate group without the electron transport chain, occurring during glycolysis and the Krebs cycle.

absorption spectrum

A graph that shows the amount of pigment absorbed at different wavelengths.

autotroph

An organism that makes its own energy by converting solar energy into glucose through photosynthesis.

C3 plant

A type of plant that uses rubisco to fix CO2 into a three-carbon molecule.

C4 plant

A type of plant that uses PEP to fix CO2 into a four-carbon molecule, which is more efficient in hot, dry conditions.

Calvin cycle

The second step of photosynthesis where CO2 is converted into glucose in the stroma, without light.

CAM plant

Plants that utilize crassulacean acid metabolism, an adaptation for photosynthesis in arid conditions.

carbon fixation

The process where rubisco catalyzes the conversion of CO2 into organic compounds, the first step in photosynthesis.

carotenoid

Pigments that capture light energy to support chlorophyll and protect plants from solar damage.

chlorophyll

The green pigment in plants that plays a key role in photosynthesis.

cyclic electron flow

A process whereby electrons are recycled back to photosystem I from the electron transport chain.

electromagnetic spectrum

The range of all types of electromagnetic radiation, including different wavelengths of light.

glyceraldehyde 3-phosphate (G3P)

A product of carbon fixation in the Calvin cycle.

heterotroph

An organism that obtains energy by consuming glucose through cellular respiration.

light-dependent reactions

The first stage of photosynthesis occurring in the thylakoid membranes, converting sunlight into ATP and NADPH.

NADP+

An electron carrier in photosynthesis that is reduced to NADPH.

non-cyclic electron flow

A linear process in photosynthesis where electrons move through both photosystems.

PGA

3-phosphoglycerate, the first stable product of carbon fixation.

photon

A particle of light.

photosystem I

The second protein complex in the thylakoid membrane involved in capturing light energy to synthesize ATP and NADPH.

photosystem II

The first protein complex in the thylakoid membrane that absorbs sunlight and initiates the photosynthetic process.

rubisco

The enzyme that catalyzes the reaction of CO2 and RuBP during carbon fixation.

spectrophotometer

An analytical instrument used to measure the intensity of light across different frequencies.

stomata

Pores located on the surface of plant leaves that facilitate gas exchange.

wavelength

The distance between successive peaks of a wave, important in the context of light.