Cellular Respiration and Photosynthesis Test + Quiz Prep - Week 9

Comprehensive vocabulary flashcards covering the processes, structures, biochemical pathways, and terminology of cellular respiration and photosynthesis from the lecture notes and chapter glossary.

Absorption Spectrum

A graph of the amount of light at specific wavelengths that is absorbed as light passes through a substance; each type of molecule has a characteristic absorption spectrum.

Aerobic Respiration

The breakdown of glucose across four major stages—glycolysis, pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation—yielding about $36\text{–}38\text{ ATP}$ per glucose.

Alcohol Fermentation

An anaerobic pathway in yeast where pyruvic acid is converted to two-carbon acetaldehyde with the release of $\text{CO}_2$, and acetaldehyde is reduced while $\text{NADH}$ is oxidized to $\text{NAD}^+$.

Autotroph

An organism that synthesizes complex organic compounds from simple inorganic raw materials; also called producer or primary producer.

$\text{C}_3$ Plant

A plant that carries out carbon fixation solely by the Calvin cycle.

$\text{C}_4$ Plant

A plant that fixes carbon initially by a pathway in which the reaction of $\text{CO}_2$ with phosphoenolpyruvate is catalyzed by PEP carboxylase in leaf mesophyll cells; the products are transferred to bundle sheath cells where the Calvin cycle takes place.

Calvin Cycle

A cyclic series of reactions in the chloroplast stroma in photosynthesis; fixes carbon dioxide and produces carbohydrate.

CAM Plant / Crassulacean Acid Metabolism

A plant that carries out crassulacean acid metabolism; carbon is initially fixed into organic acids at night in the reaction of $\text{CO}_2$ and phosphoenolpyruvate catalyzed by PEP carboxylase, and during the day the acids break down to yield $\text{CO}_2$ for the Calvin cycle.

Carbon Fixation Reactions

Reduction reactions of photosynthesis in which carbon from carbon dioxide becomes incorporated into organic molecules, leading to the production of carbohydrate.

Chemiosmosis

The process by which phosphorylation of ADP to form ATP is coupled to the transfer of electrons down an electron transport chain; proton pumps produce a proton gradient across the membrane, and ATP is formed as protons diffuse through transmembrane channels in ATP synthase.

Chlorophyll

A group of light-trapping green pigments found in most photosynthetic organisms; chlorophyll a appears blue-green and chlorophyll b appears light green.

Chloroplasts

Membranous organelles that are the sites of photosynthesis in eukaryotes; occur in some plant and algal cells.

Citric Acid Cycle

A respiratory stage in the mitochondrial matrix that recycles acetyl groups; each recycled acetyl group yields $1\text{ ATP}$, $3\text{ NADH}$, and $1\text{ FADH}_2$ (totaling $2\text{ ATP}$, $6\text{ NADH}$, and $2\text{ FADH}_2$ per glucose), and regenerates oxaloacetate.

Cyclic Electron Transport

In photosynthesis, the cyclic flow of electrons through photosystem I; ATP is formed by chemiosmosis, but no photolysis of water occurs, and $\text{O}_2$ and NADPH are not produced.

Electron Transport System

A series of chemical reactions during which hydrogens or their electrons are passed along an electron transport chain from one acceptor molecule to another, with the release of energy.

Glycolysis

The first stage of cellular respiration, literally the 'splitting of sugar'; the metabolic conversion of glucose into pyruvate, accompanied by the net production of $2\text{ ATP}$ and $2\text{ NADH}$.

Granum

A stack of thylakoids within a chloroplast (plural: grana).

Lactic Acid Fermentation

An anaerobic pathway in muscles and certain bacteria where pyruvate plus $\text{NADH}$ and $\text{H}^+$ forms lactic acid plus $\text{NAD}^+$, regenerating $\text{NAD}^+$ to keep glycolysis running and yielding $2\text{ ATP}$.

Light-Dependent Reactions

Reactions of photosynthesis in which light energy absorbed by chlorophyll is used to synthesize ATP and usually NADPH; includes cyclic electron transport and noncyclic electron transport.

Light-Independent Reactions

The stage of photosynthesis that uses ATP, NADPH, and carbon dioxide to synthesize glucose and carbohydrates.

Mesophyll

Photosynthetic tissue in the interior of a leaf; sometimes differentiated into palisade mesophyll (tightly packed cells) and spongy mesophyll (airy, spaced-out cells).

$$\text{NADP}^+/\text{NADPH}$$

Oxidized and reduced forms, respectively, of nicotinamide adenine dinucleotide phosphate; a coenzyme that acts as an electron (hydrogen) transfer agent, particularly in anabolic pathways, including photosynthesis.

Noncyclic Electron Transport

In photosynthesis, the linear flow of electrons, produced by photolysis of water, through photosystems II and I; results in the formation of ATP (by chemiosmosis), NADPH, and $\text{O}_2$.

Oxaloacetate

A four-carbon compound that is an important intermediate in the citric acid cycle and in the $\text{C}_4$ and CAM pathways of carbon fixation in photosynthesis.

P680

Chlorophyll a molecules that serve as the reaction center of photosystem II, transferring photoexcited electrons to a primary acceptor; named by their absorption peak at $680\,\text{nm}$.

P700

Chlorophyll a molecules that serve as the reaction center of photosystem I, transferring photoexcited electrons to a primary acceptor; named by their absorption peak at $700\,\text{nm}$.

Phosphoenolpyruvate (PEP)

A three-carbon phosphorylated compound that is an important intermediate in glycolysis and is a reactant in the initial carbon fixation step in $\text{C}_4$ and CAM photosynthesis.

Phosphoglycerate (PGA)

A phosphorylated three-carbon compound that is an important metabolic intermediate.

Photoautotroph

An organism that obtains energy from light and synthesizes organic compounds from inorganic raw materials; includes plants, algae, and some bacteria.

Photoheterotroph

An organism that can carry out photosynthesis to obtain energy but cannot fix carbon dioxide and therefore requires organic compounds as a carbon source; includes some bacteria and archaea.

Photolysis

The photochemical splitting of water in the light-dependent reactions of photosynthesis; catalyzed by a specific enzyme.

Photon

A particle of electromagnetic radiation; one quantum of radiant energy.

Photophosphorylation

The production of ATP in photosynthesis.

Photorespiration

The process that reduces the efficiency of photosynthesis in $\text{C}_3$ plants during hot spells in summer; consumes oxygen and produces carbon dioxide through the degradation of Calvin cycle intermediates.

Photosynthesis

The biological process that captures light energy and transforms it into the chemical energy of organic molecules (e.g., carbohydrates) manufactured from carbon dioxide and water; summarized as $6\text{CO}_2 + 12\text{H}_2\text{O} + \text{light energy} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 + 6\text{H}_2\text{O}$.

Photosystem

One of two photosynthetic units responsible for capturing light energy and transferring excited electrons; photosystem I strongly absorbs light of about $700\,\text{nm}$, whereas photosystem II strongly absorbs light of about $680\,\text{nm}$.

Phototroph

An organism that uses light as a source of energy.

Pyruvate Oxidation

The stage of aerobic respiration where three-carbon pyruvate crosses the mitochondrial membrane into the matrix, releasing $\text{CO}_2$ and $\text{NADH}$ to form two-carbon acetyl groups for the citric acid cycle.

Reaction Center

The portion of a photosystem that includes chlorophyll a molecules capable of transferring electrons to a primary electron acceptor, which is the first of several electron acceptors in a series.

Ribulose Bisphosphate (RuBP)

A five-carbon phosphorylated compound with a high energy potential that reacts with carbon dioxide in the initial step of the Calvin cycle.

Rubisco

The common name of ribulose bisphosphate carboxylase/oxygenase; the enzyme that catalyzes the fixation of carbon dioxide in the Calvin cycle.

Stomata

Small pores located in the epidermis of plants that provide for gas exchange for photosynthesis; each stoma is flanked by two guard cells responsible for opening and closing.

Stroma

A fluid space of the chloroplast, enclosed by the chloroplast inner membrane and surrounding the thylakoids; site of the reactions of the Calvin cycle.

Thylakoids

An interconnected system of flattened, saclike, membranous structures inside the chloroplast; contains an internal space termed the thylakoid lumen.

Wavelength

The distance from one wave peak to the next; the energy of electromagnetic radiation is inversely proportional to its wavelength.