AP BIO Ch. 1-5 Vocab

Molecule

A chemical structure consisting of two or more atoms bonded together.

Organelles

Various functional components within a cell that perform specific tasks.

Cell

Life’s fundamental unit of structure and function; can be unicellular or multicellular.

Tissue

A group of cells working together to perform a specialized function.

Organ

A body part made up of multiple tissues that has specific functions.

Organism

An individual living thing.

Species

A group whose members can reproduce only with members of the same group.

Population

All individuals of a species living in a defined area that interbreed.

Community

Populations of different species living in a particular area.

Ecosystem

All living things in an area plus the nonliving components the organisms interact with.

Biosphere

All life on Earth and the places where life exists (land, water, air, sediments).

Producers

Photosynthetic organisms that capture energy from the sun.

Consumers

Organisms that obtain energy by feeding on other organisms.

Energy flow (in ecosystems)

Energy enters as light and flows in one direction; chemicals cycle and are reused.

DNA

Hereditary material; encodes information for building cellular molecules.

Cell membrane

The phospholipid bilayer that encloses a cell and regulates material passage.

Prokaryotic

Organisms without a nucleus or membrane-bound organelles, e.g., bacteria and archaea.

Eukaryotic

Cells with a nucleus and membrane-bound organelles.

Nucleus

Membrane-bound organelle that houses DNA in eukaryotic cells.

Gene

A unit of inheritance; a specific DNA sequence that encodes a product.

Darwin’s natural selection

Process where inherited traits that confer a reproductive advantage become more common.

Descent with modification

Over time, species accumulate differences from their ancestors.

Hypothesis

A testable explanation or educated guess based on observations.

Negative feedback

Regulatory loop where the output reduces the initial stimulus to maintain stability.

Positive feedback

Regulatory loop where the output speeds up its own production.

Quantitative data

Data expressed as numbers suitable for statistical analysis.

Qualitative data

Descriptive data expressed in words or observations.

Controlled experiment

An experiment comparing an experimental group with a control group, changing one variable.

Theory (scientific meaning)

A well-supported, evidence-based explanation that can be revised with new data.

Element

A substance that cannot be broken down into simpler substances by chemical means.

Compound

Substance containing two or more different elements in fixed ratios.

Essential elements

Elements organisms must have to live and reproduce.

Trace elements

Elements required in minute amounts; not all are essential for every organism.

C, H, O, N

Elements that make up about 96% of living matter.

Atom

The smallest unit of an element that retains its properties; consists of protons, neutrons, and electrons.

Proton

Positively charged subatomic particle in the nucleus.

Neutron

Electrically neutral subatomic particle in the nucleus.

Electron

Negatively charged subatomic particle in the electron cloud.

Atomic number

Number of protons in an atom; unique to each element.

Mass number

Total number of protons and neutrons in an atom.

Isotope

Different atomic forms of the same element with varying neutron numbers.

Radiometric dating

Technique that uses radioactive isotopes to estimate the age of materials.

Polarity

Unequal sharing of electrons leading to partially positive and negative regions.

Hydrogen bond

A weak attraction between a hydrogen atom and an electronegative atom (often O or N).

Cohesion

Attraction between water molecules due to hydrogen bonding.

Adhesion

Clinging of one substance to another, e.g., water to plant cell walls.

Surface tension

Tendency of a liquid surface to resist external force due to cohesive forces.

Specific heat

Amount of heat needed to raise the temperature of 1 g of a substance by 1°C; water has a high one.

Heat of vaporization

Energy required for water to change from liquid to gas.

Capillary action

Movement of water up narrow tubes due to cohesion and adhesion.

Solvent

Dissolving agent in a solution.

Solute

Substance dissolved in a solvent.

Solution

Homogeneous mixture of solute dissolved in solvent.

Hydrophobic

Water-fearing; nonpolar substances that repel water.

Hydrophilic

Water-loving; substances that readily interact with water.

Acid

Substance that increases H+ concentration in solution.

Base

Substance that reduces H+ concentration in solution.

pH

A measure of the hydrogen ion concentration of a solution.

Buffer

Substance that minimizes changes in pH by neutralizing added acids or bases.

Bicarbonate buffer system

Body’s major buffer maintaining blood pH by balancing carbonic acid and bicarbonate ions.

Carbon

Element with 4 valence electrons capable of forming diverse organic molecules.

Carbon skeleton

Foundations of organic molecules; can be straight, branched, or ringed.

Hydrocarbon

Molecule composed of only carbon and hydrogen; typically hydrophobic.

Isomer

Compounds with the same formula but different structures.

Structural isomer

Isomers differing in covalent arrangement of atoms.

Geometric (cis-trans) isomer

Isomers differing in spatial arrangement around a double bond.

Enantiomer

Mirror-image isomer; often only one form is biologically active.

Functional group

A specific group of atoms responsible for characteristic chemical reactions.

Hydroxyl (-OH)

Polar group capable of hydrogen bonding; common in alcohols.

Carbonyl (C=O)

Polar group; key in aldehydes and ketones.

Carboxyl (-COOH)

Acidic group that donates H+; found in organic acids.

Amino (-NH2)

Basic group that accepts H+; part of amino acids.

Sulfhydryl (-SH)

Group that can form disulfide bonds stabilizing protein structure.

Phosphate (-OPO3 2-)

Negatively charged group important in nucleotides and energy transfer.

Methyl (-CH3)

Nonpolar group that can affect gene expression when attached to DNA or proteins.

Monomer

Smallest unit that can join to form a polymer.

Polymer

Long molecule made of repeating monomer units.

Monosaccharide

Simple sugar; basic unit of carbohydrates (e.g., glucose).

Disaccharide

Two monosaccharides joined by a glycosidic linkage.

Polysaccharide

Polymers of glucose; used for energy storage or structure (e.g., starch, cellulose).

Glycosidic linkage

Covalent bond joining monosaccharides.

Alpha glycosidic linkage

Glycosidic bond in starch; easily hydrolyzed by amylase.

Beta glycosidic linkage

Glycosidic bond in cellulose; not easily digested by humans.

Starch

Plant storage polysaccharide with alpha linkages.

Glycogen

Animal storage polysaccharide with alpha linkages.

Cellulose

Structural polysaccharide with beta linkages; forms plant cell walls.

Chitin

Structural polysaccharide in arthropods and fungi.

Symbiosis

Close and long-term interaction between different species.

Fat

Glycerol with three fatty acids; a storage lipid; nonpolar.

Phospholipid

Lipid with glycerol, two fatty acids, and a polar phosphate head; forms membranes.

Steroid

Lipid with four fused rings (e.g., cholesterol).

Saturated fat

Fat with no double bonds; typically solid at room temperature.

Unsaturated fat

Fat with one or more double bonds; typically liquid at room temperature.

Cis fat

Hydrogens on the same side of a double bond; causes kinks.

Trans fat

Hydrogens on opposite sides of a double bond; can pack tightly.

Cholesterol

Steroid lipid essential for membranes and steroid synthesis.

Amino acid

Amino group, carboxyl group, central carbon, and R group; building blocks of proteins.

Peptide bond

Covalent bond linking amino acids in a polypeptide.

R-group

The variable side chain of an amino acid determining its properties.

Primary structure

Linear sequence of amino acids in a polypeptide.