Learn: Biology: Key Concepts, Scientific Method, and Data Analysis

Science

The process of studying the natural world by making observations, asking questions, testing ideas, and using evidence.

Goals of science

Describe the natural world, explain why things happen, predict what may happen, and understand patterns in nature.

Observation

What you directly notice or measure.

Inference

An explanation or conclusion based on observations.

Hypothesis

A testable explanation or prediction.

Qualitative data

Data that describes qualities, such as color, smell, or appearance.

Quantitative data

Data that uses numbers or measurements.

Independent variable (IV)

The variable the scientist changes.

Dependent variable (DV)

The variable the scientist measures.

Controlled variables

Things kept the same throughout an experiment.

Experimental group

The group that receives the variable or treatment being tested.

Control group

The comparison group that does not receive the experimental treatment.

Skepticism

Questioning claims and asking for evidence.

Objectivity

Using evidence without allowing personal opinions or feelings to influence results.

Bias

A personal preference or influence that can affect interpretation.

Transparency

Clearly explaining how research was performed and where information came from.

Peer review

Other scientists in the same field examine a scientist's work before publication.

Scientific theory

A well-supported explanation of natural phenomena that has been repeatedly tested and supported by evidence.

Primary source

Original research by the scientists who conducted the study.

Secondary source

A source that summarizes or discusses research done by others.

Line graph

A graph good for showing change over a period of time.

Scatter plot

A graph good for showing a relationship or correlation between two variables.

Bar graph

A graph used for comparing distinct categories or groups.

Pie/circle graph

A graph used for showing parts of a whole, often as percentages.

Biology

The study of life.

Cell

The basic unit of life.

Autotroph

An organism that makes its own food; also called a producer.

Heterotroph

An organism that gets food or energy by consuming other organisms or organic material; also called a consumer.

Metabolism

All chemical reactions occurring within an organism.

Stimulus

A change in the environment that causes a response.

Homeostasis

Maintaining a stable internal environment.

Evolution

Change in populations over generations.

Adaptation

A characteristic that helps an organism survive and reproduce in its environment.

Reproduction

The process of producing offspring.

Prokaryotic cell

A simpler cell that lacks a nucleus.

Eukaryotic cell

A more complex cell that has a nucleus.

Asexual reproduction

Reproduction involving one parent that produces genetically similar offspring.

Sexual reproduction

Reproduction that combines genetic material from two parents and produces more variation.

Spontaneous generation

The old idea that living things could arise from nonliving matter.

Biogenesis

The idea that living things come from other living things.

Atom

The basic unit of matter.

Proton

A positively charged subatomic particle found in the nucleus.

Neutron

A subatomic particle with no charge found in the nucleus.

Electron

A negatively charged subatomic particle found in the electron cloud.

Atomic number

The number of protons in an atom.

Mass number

The number of protons plus neutrons.

Atomic mass

The weighted average of the masses of an element's naturally occurring isotopes.

Isotopes

Atoms of the same element with the same number of protons but different numbers of neutrons.

CHON

Carbon, Hydrogen, Oxygen, and Nitrogen.

Molecule

Two or more atoms chemically bonded together.

Compound

A molecule containing two or more different elements.

Ion

An atom or molecule with a charge, formed when electrons are gained or lost.

Ionic bond

A bond formed when electrons are transferred, producing oppositely charged ions that attract.

Covalent bond

A bond in which atoms share electrons.

Water formula

H₂O.

Polarity of water

Water is polar; oxygen is slightly negative and the hydrogen side is slightly positive.

Cohesion

Water sticking to water.

Adhesion

Water sticking to other substances.

Hydrophilic

Attracted to water.

Hydrophobic

Avoids water.

Capillary action

Movement of water through narrow spaces due to cohesion and adhesion.

Specific heat of water

Water takes a relatively large amount of energy to change temperature, helping stabilize temperatures.

pH scale

A scale from 0 to 14.

Acidic

pH 0-6.9.

Neutral

pH 7.

Basic

pH 7.1-14.

Buffer

A solution that resists large changes in pH.

Carbohydrates

Biomolecules mainly made of C, H, and O; functions include quick energy, energy storage, and structure.

Lipids

Biomolecules mainly made of C, H, and O; functions include long-term energy storage, cell membranes, insulation, and some signaling.

Proteins

Biomolecules usually made of C, H, O, and N; functions include enzymes, transport, structure, movement, defense, and signaling.

Nucleic acids

Biomolecules made of C, H, O, N, and P; include DNA and RNA.

Monomer

A basic building block of a larger molecule.

Polymer

A larger molecule made of repeating monomers.

Monosaccharide

A simple sugar and the monomer of carbohydrates.

Amino acid

The monomer of proteins; amino acids are connected by peptide bonds.

Nucleotide

The monomer of nucleic acids; made of a sugar, phosphate group, and nitrogen-containing base.

DNA

A nucleic acid usually double-stranded that stores genetic information.

RNA

A nucleic acid usually single-stranded that helps use genetic information to make proteins.

Saturated fatty acid

A fatty acid with no carbon-carbon double bonds.

Unsaturated fatty acid

A fatty acid with one or more carbon-carbon double bonds.

Chemical reaction

A process in which substances are rearranged to form new substances.

Reactants

Substances present before a chemical reaction.

Products

Substances produced after a chemical reaction.

Activation energy

The minimum energy needed to start a chemical reaction.

Catalyst

A substance that speeds up a reaction by lowering activation energy and is not used up by the reaction.

Enzyme

A biological catalyst, usually a protein.

Active site

The specific region of an enzyme where the substrate binds and the reaction occurs.

Substrate

The molecule acted on by an enzyme.

Denaturation

When a protein changes shape and can no longer function properly.

Factors affecting enzymes

Temperature and pH are major factors; substrate concentration and enzyme concentration can also affect reaction rate.