Characteristics of Life, Biomolecules, and the Scientific Method Flashcards

Vocabulary flashcards covering the characteristics of living organisms, biological organization, biomolecules (carbohydrates, lipids, proteins, nucleic acids, ATP), and the steps and variables of the scientific method.

Biology

A natural science derived from the Greek words bios ("life") and logos ("study"), meaning "the study of life"; it examines living things, their interactions, structure, function, growth, evolution, and classification.

Atom

The smallest unit of an element, composed of protons, neutrons, and electrons.

Molecule

A union between 2 or more atoms, which can be of the same or different elements.

Cell

The smallest living unit, composed of many molecules; can be prokaryotic or eukaryotic.

Tissue

A group composed of many cells with the same structure, purpose, and function.

Organ

A group of tissues functioning together for a specific purpose.

Organ System

A group of organs functioning together for a specific purpose.

Organism

An individual composed of multiple organ systems.

Population

A group of organisms ONLY from the same species.

Community

Different interacting populations in a particular area.

Ecosystem

A community plus its non-living surroundings (community + physical environment).

Biosphere

All ecosystems combined.

Photosynthesis

The process by which plants use $CO_2$, $H_2O$, and solar energy to make their own food.

Cellular Respiration

The process by which humans and other organisms acquire materials and energy by eating food.

Homeostasis

The state of staying in the same conditions or maintaining internal equilibrium (e.g., blood sugar, temperature).

Growth

An increase in the size of an organism or in the number of cells.

Development

All the changes that take place between conception and death, including repairs following an injury.

Adaptation

A particular variation that allows certain species to survive in a new environment.

Fitness

The tendency of individuals of a species that are better adapted to their environment to live longer and produce more offspring.

Evolution through Natural Selection

The change in the frequency of traits in a population and species over time.

Inorganic Molecules

Molecules that make up nonliving matter but are important for life, such as water and salt.

Organic Molecules (Biomolecules)

Molecules that make up living matter, containing carbon and hydrogen atoms, where carbon forms 4 covalent bonds in chains or rings.

Monomer

A smaller molecular building block of biomolecules ("mono" means "one").

Polymer

A larger biomolecule made up of multiple linked monomers ("poly" means "multiple").

Dehydration Reaction

A chemical reaction in which monomers combine to make a polymer by removing water.

Hydrolysis Reaction

A chemical reaction in which polymers break down into monomers as water breaks the bonds between them.

Carbohydrates

Biomolecules with the atomic grouping $H - C - OH$ (2:1 hydrogen-to-oxygen ratio) that function as quick fuel, short-term energy storage, and organism structure.

Monosaccharides

Simple carbohydrate sugars containing 3 to 7 carbon atoms, such as glucose, fructose, and galactose.

Disaccharides

Simple carbohydrates composed of 2 monosaccharides linked by a glycosidic bond, such as sucrose, lactose, and maltose.

Polysaccharides

Complex carbohydrates composed of many monosaccharides linked together, such as starch, glycogen, and cellulose.

Lipids

Hydrophobic, hyper-caloric biomolecules containing $9\text{ cal/g}$ used for long-term energy storage, insulation, organ cushioning, and cell membranes.

Saturated Fatty Acid

A fatty acid containing only single bonds in its hydrocarbon chain.

Unsaturated Fatty Acid

A fatty acid containing at least one double bond in its hydrocarbon chain.

Trans Fatty Acid

A type of fatty acid resulting from the hydrogenation of unsaturated fatty acids.

Triglycerides

Lipids composed of 1 glycerol and 3 fatty acids joined by ester linkages; categorized into liquid plant oils and solid animal fats.

Phospholipids

Primary components of cell membranes composed of a polar, hydrophilic head group, a glycerol backbone, and two non-polar, hydrophobic fatty acid tails forming a bilayer.

Steroids

Lipids characterized by a backbone of 4 fused carbon rings, such as cholesterol, estrogen, and testosterone.

Proteins

Biomolecules made of amino acids yielding $4\text{ cal/g}$ that perform structural, enzymatic, transport, immune, regulatory, and contractile functions.

Polypeptide

A single chain of amino acids joined together through peptide bonds.

Nucleic Acids

Polymers made of nucleotide monomers composed of a sugar and phosphate backbone with nitrogenous bases projecting to one side.

DNA (Deoxyribonucleic Acid)

A double-stranded helical nucleic acid containing deoxyribose sugar and adenine, thymine, guanine, and cytosine bases that stores and transmits genetic information.

RNA (Ribonucleic Acid)

A single-stranded nucleic acid containing ribose sugar and adenine, uracil, guanine, and cytosine bases that carries genetic information specifically for making proteins.

ATP (Adenosinetriphosphate)

The cellular unit of energy composed of ribose sugar, adenine, and 3 phosphate groups that controls and powers most cellular work.

ATPase

An enzyme that catalyzes the conversion of ATP to ADP by removing a phosphate group to release energy for cellular work.

ATP Synthase

An enzyme that catalyzes the conversion of ADP to ATP by attaching a phosphate group to store energy.

Scientific Method

A way of acquiring knowledge by making observations, asking questions, proposing explanations, testing them, and drawing conclusions based on evidence.

Observation

The step of the scientific method involving gathering information using the senses or instruments, as well as studying previous data.

Independent Variable

The specific variable in an experiment that is intentionally changed or manipulated by the experimenter.

Dependent Variable

The variable in an experiment that is measured and changes as a result of manipulating the independent variable.

Control Variable

Any condition or factor in an experiment that is kept constant throughout the experiment.

Control Group

A group in an experiment that goes through all the standard steps but lacks the specific variable being tested.

Hypothesis

A testable statement usually formatted as "IF (…) THEN (…)" that predicts how one variable will affect another.

Data

The observable and objective results collected during an experiment, often displayed in graphs or tables.

Cell Theory

A biological theory stating that all organisms are composed of cells, and new cells only come from preexisting cells.

Homeostasis Theory

A biological theory stating that the internal environment of an organism stays relatively constant within a protective range.

Gene Theory

A biological theory stating that organisms contain coded information that dictates their form, function, and behavior.

Ecosystem Theory

A biological theory stating that organisms are members of populations that interact with each other and the physical environment in a particular locale.

Evolution Theory

A biological theory defined as a change in the frequency of traits that affect reproductive success in a population or species across generations.