Scientific Method, Cell Structure, and Bioenergetics Vocabulary

A complete set of vocabulary flashcards covering basic scientific principles, experimental design, cell structure, transport, photosynthesis, and cellular respiration directly based on lecture notes.

Science

A field based on cause-and-effect relationships and rational thinking about the physical world.

Galileo

A 17th-century scientist who used experiments instead of speculation and was an early figure in formalizing the scientific method.

Francis Bacon

An early figure who helped formalize the scientific method alongside Galileo.

Scientific Method Steps

The six steps in order: 1. Observe, 2. Question, 3. Hypothesis, 4. Predict, 5. Test prediction, 6. Draw a conclusion (O $\rightarrow$ Q $\rightarrow$ H $\rightarrow$ P $\rightarrow$ T $\rightarrow$ C).

Scientific Hypothesis

An educated guess that tentatively answers a question or solves a problem concerning the physical world; it must be testable, capable of being shown wrong, and follow the principle of falsifiability.

Falsifiability

The principle that there must be a possible test that could show a hypothesis is wrong.

Fact

Something that competent observers can observe and agree to be true.

Theory

A synthesis of facts and well-tested hypotheses that serves as a foundation of science and grows stronger and more precise as new information is added.

Law / Principle

A scientific hypothesis that has been tested repeatedly and has not been contradicted.

Discovery-Based Science

A branch of science that uses observational studies and detailed descriptions of events.

Qualitative Data

Data based on observation that does not use numerical values.

Quantitative Data

Data that uses numerical values, usually obtained through measurement.

Hypothesis-Based Science

Science that uses the scientific method to assess explanations about a natural phenomenon through experimental design and testing.

Null Hypothesis

A hypothesis stating that there is NO difference between treatments or NO cause-and-effect relationship.

Alternative Hypothesis

A hypothesis stating that there IS a difference between treatments or IS a relationship between variables.

Independent Variable

The variable being manipulated in an experiment.

Levels of Treatment

The different amounts or categories of the independent variable used in an experiment.

Dependent Variable

The variable being measured or observed in an experiment.

Standardized Variables

Variables that are kept the same throughout an experiment.

Control Group

A comparison group used to help determine whether an experimental treatment caused an effect.

Positive Control

A control group expected to produce a known or expected result.

Negative Control

A control group expected to produce no effect or result.

Replication

Repeating an experiment or trials to improve reliability.

Cell

The smallest unit of life.

Unicellular

Describing an organism made of one single cell.

Multicellular

Describing an organism made of many cells.

Prokaryotes

Unicellular organisms (Bacteria and Archaea) that appeared about $3.5$ billion years ago, usually $1\text{–}10\text{ }\frac{}{}\text{μm}$ in size, and lack a nucleus.

Eukaryotes

Organisms (Animals, Plants, Fungi, Protists) that appeared about $2$ billion years ago, contain a membrane-enclosed nucleus, and are about $10,000\times$ larger than prokaryotes by volume.

Anton van Leeuwenhoek

An early scientist who observed bacteria, sperm, and moving protists, coining the term animacules.

Robert Hooke

The scientist who coined the term "cell" (cellulae) after examining thin pieces of cork.

Schleiden & Schwann

The scientists who developed cell theory, establishing that all living things are composed of cells and cells arise from preexisting cells.

Cytoplasm

The cellular region between the plasma membrane and nuclear membrane, containing organelles suspended in cytosol and consisting of about $70\text{–}80$% water.

Plasma Membrane

A boundary found in all cells composed of a phospholipid bilayer and membrane proteins.

Phospholipids

Molecules that form the membrane bilayer with hydrophobic tails facing inward to prevent leaking and create a cell boundary.

Transmembrane Proteins

Membrane proteins that penetrate the entire lipid bilayer.

Surface Proteins

Membrane proteins located primarily on the inner or outer surface of the plasma membrane.

Diffusion

A type of passive transport where solute moves down a concentration gradient from HIGH to LOW concentration without energy.

Simple Diffusion

Passive transport where small, uncharged molecules like $O_2$ and $CO_2$ pass directly through the plasma membrane.

Facilitated Diffusion

Passive movement of molecules across a membrane down their concentration gradient using transport proteins.

Osmosis

The diffusion of water across a membrane from high to low water concentration to equalize concentration.

Aquaporins

Hydrophilic transmembrane proteins that act as water channels to allow most water flow through the membrane.

Tonicity

The relationship between the concentration of solutes inside versus outside the cell.

Nucleoid

The region inside a prokaryotic cell where DNA is located.

Peptidoglycan

The component of the bacterial cell wall that provides protection and prevents dehydration.

Nucleus

A membrane-enclosed structure in eukaryotic cells containing linear DNA.

Chromatin

Long, thin fibers made of DNA and proteins that prevent DNA from tangling and coil into chromosomes during cell division.

Rough ER

Endoplasmic reticulum studded with ribosomes, connected to the nuclear envelope, that folds and packages proteins and produces membrane.

Smooth ER

Endoplasmic reticulum without ribosomes that forms part of the endomembrane system.

Ribosomes

Structures made of large and small subunits responsible for protein synthesis; found free in cytoplasm or bound to ER/nuclear envelope.

Golgi Apparatus

The cell's packaging center, consisting of flattened stacks of membranes that process/package proteins and lipids, and synthesize carbohydrates.

Lysosomes

Acid-filled, membrane-enclosed vesicles containing digestive enzymes that act as the cell's digestion and recycling center.

Mitochondria

Organelles responsible for energy processing and ATP production with a structure that maximizes surface area.

Cell Wall

A structural layer surrounding the plasma membrane, made of cellulose in plant cells.

Vacuole

A prominent plant cell organelle occupying $50\text{–}90$% of the cell interior that provides physical support.

Turgor Pressure

Fluid pressure pushing against the cell wall that allows plant stems and flowers to remain upright.

Chloroplast

A double-membrane organelle found in plants and eukaryotic algae responsible for photosynthesis.

Stroma

The fluid filling the interior of a chloroplast where the light-independent Calvin Cycle ("synthesis") takes place.

Thylakoids

Interconnected membranous structures inside a chloroplast where light-dependent ("photo") reactions take place.

Grana

Stacks or arrangements of thylakoids within a chloroplast.

Energy

The capacity to do work.

Kinetic Energy

Energy of motion, such as heat and light.

Potential Energy

Stored energy resulting from an object's location or position, such as concentration gradients.

ATP

Adenosine Triphosphate; the cellular energy source produced when organisms break down glucose and carbohydrates.

Catalysts

Substances that lower activation energy without being changed themselves during chemical processes.

Chlorophyll

Abundant pigments (types a and b) in leaves that reflect green light and break down in autumn to expose carotenoids.

Light-Dependent Reactions

The photosynthetic stage in thylakoids that uses sunlight to produce $O_2$ and convert energy into ATP and NADPH.

Light-Independent Reactions

Also called the Calvin Cycle; the photosynthetic stage in the stroma that uses ATP and NADPH to fix $CO_2$ into glucose.

Cellular Respiration

An oxygen-requiring process summarizing C_6H_{12}O_6 + 6O_2 + \text{\textasciitilde}}38ADP \rightarrow 6CO_2 + 6H_2O + \text{\textasciitilde}}38ATP to produce cellular energy.

Oxidation

The removal of electrons (remembered by "OIL" - Oxidation Is Loss).

Reduction

The gain of electrons (remembered by "RIG" - Reduction Is Gain).

Redox Reaction

A chemical reaction combining an oxidation reaction with a reduction reaction.

NAD

An electron carrier that accepts electrons and hydrogen during biological oxidation to become NADH.

NADH

A reduced electron carrier holding high-energy electrons.

Glycolysis

The first step of cellular respiration.

Krebs Cycle

A stage of cellular respiration in the mitochondria that extracts energy from acetyl-CoA to produce ATP, NADH, and $FADH_2$.

Electron Transport Chain (ETC)

The final mitochondrial stage of cellular respiration where NADH and $FADH_2$ are used to build about $90$% of the ATP harvested from glucose.