Unit 4 Biology Study Guide: Energy, Photosynthesis, and Cellular Respiration

A complete set of vocabulary flashcards for Unit 4 Biology covering energy flow, thermodynamics, photosynthesis, cellular respiration, and fermentation.

Thermodynamics

The study of the flow and transformation of energy in the universe.

First Law of Thermodynamics

The law of conservation of energy, which states that energy can be converted from one form to another, but cannot be created or destroyed.

Second Law of Thermodynamics

The law stating that energy conversions always result in a loss of usable energy, increasing entropy (disorder).

Entropy

Disorder or unusable energy that increases whenever energy is converted from one form to another.

Metabolism

All of the chemical reactions that occur within a cell.

Catabolic Pathways

Metabolic pathways that break down larger molecules to release energy, such as cellular respiration.

Anabolic Pathways

Metabolic pathways that consume energy to build larger molecules, such as photosynthesis.

Adenosine Triphosphate (ATP)

The primary biological nucleotide molecule that stores and provides chemical energy for cellular processes, composed of an adenine base, a ribose sugar, and three phosphate groups.

ADP (Adenosine Diphosphate)

The molecule formed when the bond between the second and third phosphate groups of ATP is broken to release energy for cellular work.

Autotroph

An organism that makes its own food using energy from the Sun or inorganic substances.

Heterotroph

An organism that must ingest food to obtain energy.

Chlorophyll

Plant pigments (chlorophyll a and b) that absorb various visible wavelengths while reflecting green light, making plants appear green.

Carotenoids

Accessory plant pigments that reflect red and orange light.

Xanthophylls

Accessory plant pigments that reflect yellow light.

Photosynthesis

The process occurring in chloroplasts represented by the equation $6CO_2 + 6H_2O \xrightarrow{\text{Light}} C_6H_{12}O_6 + 6O_2$, in which autotrophs capture light energy to synthesize glucose.

Thylakoid

Chlorophyll-containing membrane structures inside chloroplasts where light-dependent reactions occur.

Grana

Stacks of chlorophyll-containing thylakoid membranes located inside chloroplasts.

Stroma

The fluid-filled space surrounding the grana inside a chloroplast where the Calvin cycle takes place.

Light-Dependent Reactions

The stage of photosynthesis occurring in the thylakoid that requires light and water, excites electrons to produce ATP, and splits water to release $O_2$ gas and provide $H^+$ ions.

NADP+ (in photosynthesis)

A carrier molecule that transports $H^+$ ions produced from splitting water in the light-dependent reactions to the Calvin cycle.

Calvin Cycle (Light-Independent Reactions)

The stage of photosynthesis occurring in the stroma that uses $6CO_2$, along with ATP and $H^+$ from the light reactions, to synthesize one molecule of glucose ($C_6H_{12}O_6$).

Aerobic Cellular Respiration

The process represented by $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP}$ that breaks down glucose in the presence of oxygen across three phases to generate ATP.

Glycolysis

The anaerobic and aerobic first phase of cellular respiration occurring in the cytoplasm that splits 1 glucose using 2 ATP into 2 pyruvate, 2 NADH, and 4 ATP (net yield of 2 ATP).

Pyruvate

A 3-carbon molecule produced by the splitting of glucose during glycolysis.

Krebs Cycle

The phase of cellular respiration occurring in the mitochondrial matrix that processes pyruvate to generate energetic electrons ($NADH$ and $FADH_2$), ATP, and $6CO_2$.

Mitochondrial Matrix

The inner space of the mitochondrion where the Krebs cycle processes pyruvate.

NADH

An energetic electron carrier molecule generated during glycolysis and the Krebs cycle.

FADH2

An energetic electron carrier molecule produced during the Krebs cycle in the mitochondrial matrix.

Electron Transport Chain

The stage of cellular respiration occurring in the mitochondrial inner membrane that converts energetic electrons into ATP and $6H_2O$.

Mitochondrial Inner Membrane

The membrane structure within mitochondria where the electron transport chain operates to generate ATP and $6H_2O$.

Net ATP Yield of Aerobic Respiration

The net yield of 36 ATP (from 38 total ATP) produced per glucose molecule when combining the Krebs cycle and the electron transport chain.

Fermentation

An anaerobic pathway following glycolysis that regenerates $NAD^+$ while producing either lactic acid or ethanol and carbon dioxide.

NAD+ (in fermentation)

The electron carrier molecule that anaerobic fermentation must regenerate to allow glycolysis to continue producing a net of 2 ATP.

Alcoholic Fermentation

An anaerobic pathway carried out by yeast, fungi, and bacteria that converts pyruvate into ethanol and $CO_2$ while regenerating $NAD^+$.

Lactic Acid Fermentation

An anaerobic pathway occurring in muscle cells during intense exercise that converts pyruvate into lactic acid, causing muscle soreness while regenerating $NAD^+$.

Where do Photosynthesis and Cell Respiration occur?

Photosynthesis occurs in chloroplasts.

Cell respiration occurs in mitochondria.

What are the reactants of Photosynthesis and Cell Respiration

The reactants of Photosynthesis are 6 carbon dioxide molecules (6CO2) and 6 water molecules (6H20).

The reactants of Cell respiration are glucose and 6 oxygen molecules (6O2).

What are the products of Photosynthesis and Cell respiration?

The products of Photosynthesis are 6 oxygen molecules (6O2) and 1 glucose molecule (C6 H12 O6)

The products of Cell respiration are 6 carbon dioxide molecules (6CO2), 6 water molecules (6H2O), and Adenosine triphosphate (ATP)

Are Photosynthesis and Cell respiration Endothermic or exothermic?

Photosynthesis is Endothermic

Cell respiration is Exothermic

Anaerobic Respiration

Cell Respiration that occurs in the absence of oxygen; also known as fermentation

Lactic acid: inside body

Alcoholic: outside body

Outputs:

Ethanol and CO2(from yeast, beer, bread){Alcoholic}

Lactic acid(in muscle cells){Lactic Acid}

Mitochondria Structure

Outer membrane

Inner membrane w/ cristae(folds) for more surface area

Matrix is the fluid inside the inner membrane.