Biology Key Terms & Concepts

Principles in Biology 1: Fall 2026

Biology

The scientific study of life and living organisms and their interactions

Discovery Science

Describes nature and focuses on verifiable observations and recorded measurements

Hypothesis-Driven Science

Explains nature, seeks explanation for the data collected during discovery science, involves the scientific method

Inductive Reasoning

Derives general principles from specific observations, often used in discovery science to form hypotheses.

Deductive Reasoning

Uses general principles to deduce specific predictions, often employed in hypothesis-driven science to test hypotheses.

Scientific Method Steps

1. Form a hypothesis

2. Test your hypothesis

3. Analyze the results against your hypothesis

4. If hypothesis stands up to repeated tests it becomes a theory or law

Natural Sciences

Disciplines that study the natural world through observation and experimentation, including biology, chemistry, and physics.

Life Sciences

a branch of natural sciences that studies living organisms, their life processes, interactions, and ecosystems.

Physical Sciences

Disciplines that study the physical world, including physics, chemistry, and astronomy.

Basic Sciences

Seeks to expand knowledge

Applied Sciences

Seeks to solve real world problems

Properties of Life

1. Order

2. Responsiveness

3. Reproduction

4. Adaption

5. Growth & Development

6. Regulation & Homeostasis

7. Energy Processing

8. Evolution

Domains of Life (2)

Vertical Domain: hierarchy of organization of complexity

Horizontal Domain: diversity of life

Main Domains (3)

1. Bacteria

2. Archaea

3. Eukarya

Kingdoms of Eukarya (4)

1. Kingdom Protista

2. Kingdom Fungi

3. Kingdom Plantae

4. Kingdom Animalia

Humans need __ elements

25

The four major elements humans need are

Oxygen, Carbon, Hydrogen, and Nitrogen

Electron shell #1 can hold _ electrons.

2

Electron shell #2 can hold _ electrons.

8

Electron shell #3 can hold _ electrons.

8

An atom with an unfilled valance shell is called a

Free Radical

What particle changes in an isotope?

Neutrons

What is an Ionic Bond?

A bond where electrons are donated and oppositely charges ions are attracted to each other

What is Covalent Bond?

A bond where electrons are shared between atoms

What is a Compound?

Chemical structure that contains two or more elements

What is a Molecule?

chemical structure in which atoms share electrons

Positive Ions are called:

Cations

Negative Ions are called:

Anions

What does non-polar mean?

electrons are shared equally

What does polar mean?

electrons spend more time rotating around one atom than the other

What are some key characteristics of Hydrogen?

1. too weak to create molecules, but can help facilitate a chemical change

What are some key characteristics of Water?

1. It's a polar molecule

2. Less dense when frozen

3. High heat capacity

4. High heat of vaporization

5. Cohesive

6. Adhesive

7. Effective Solvent

What acts as a heat bank

water

What is a heat bank?

A substance that absorbs and stores heat from warmer air, and gives off heat to cooler air

What is evaporative cooling?

Process in which water absorbs heat from its surroundings when it evaporates, leading to a cooling effect

What is surface tension?

Measures how difficult it is to break the surface of a liquid

What is an aqueous solution?

Any solution in which water is the solvent

What does hydrophilic mean?

a substance will dissolve in water

What does hydrophobic mean?

a substance will NOT dissolve in water or will be repelled by water

What is an Acid?

Any substance that increases the number of hydrogen ions (H+) in a solution; pH of less than 7.

What is a Base?

Any substance that decreases the number of hydrogen ions (H+) in a solution; pH of greater than 7.

What is hydrocarbon?

An organic molecule consisting of hydrogen and carbon

What is an Isomer?

Molecules that share the same chemical formula but differ in their placement of atoms or chemical bonds

What is a Structural Isomer?

An isomer that differs in the placement of covalent bonds

What is a Geometric Isomer?

An isomer that differs in the spatial arrangement of atoms

What is enantiomer?

An isomer that is a mirror image of another molecule

What are functional groups?

Groups of atoms that occur within molecules and confer specific properties

What are Biological Molecules?

large, organic molecules

Four types of biological molecule:

Carbohydrates, proteins, lipids, nucleic acids

Formation of polymers is caused by:

Subunits are joined together by dehydration synthesis

Breakdown of polymers is caused by:

Broken down by hydrolysis; adding water

What are carbohydrates made of?

sugars, and polymers of sugars

Types of Saccharides

Monosaccharides

Disaccharides

Trisaccharides

Polysaccharides

What elements make up Carbohydrates?

Carbon, Hydrogen, Oxygen

What are carbohydrates used for in the body?

as energy

Chemical Composition of Lipids

C, H, O

Fats are important for:

energy, insulation, and cooling

Fats consist of:

one glycerol and three fatty acids

What are unsaturated fats?

a single covalent bond between the fatty acid carbons

What are unsaturated fats?

One or more double bonds between the fatty acid carbons.

What are monounsaturated fats?

fats that have one double bond

What are polyunsaturated fats?

Fats that have two or more double bonds

What are trans fats?

Fats that are produced when we create partially hydrogenated fats

What are phospholipids and what do they do?

They consist of one glycerol, two fatty acid chains and a phosphate-containing group.

They are important components of cell membranes and as structural lipids; they are also partially hydrophobic and partially hydrophillic

What are steroids?

Flat molecules formed of four interlocking hydrocarbon rings

What elements do proteins contain?

C, H, O, N and often sulfer

What are amino acids:

Protein monomers

What are amino acids joined by?

peptide bonds

Peptides are proteins with __ - __ amino acids linked together

4-9

Proteins contain more than __ amino acids

10

Protein Structure

Primary: amino acid sequance

Secondary: alpha helix or beta pleated sheet; held in position by hydrogen bonding

Tertiary: overall 3D shape, determined by side chain interactions

Quaternary: two or more polypeptide chains assembling together

What is denaturation? What causes it? What is the effect?

1. when hydrogen bonds and disulfide bonds break causing protein to unravel and lose its 3D shape

2. Changes in the environment; pH or temperature

3. Effects how proteins work and interact with other molecules

What elements does nucleic acid contain?

C, O, N, P

What are the three parts of a nucleotide?

Nitrogenous Base: ring molecule containing nitrogen

Pentose Sugar: either ribose or deoxyribose

Phosphate Group: phosphorus with four oxygen atoms bonded to it

Purine vs Pyrimidine Nitrogenous Bases

1. Adenine & Guanine

2. Thymine, Cytosine & Uracil

Nitrogen Base Pairs for DNA

Adenine & Thymine

Guanine & Cytosine

Nitrogen Base Pairs for RNA

Adenine & Uracil Guanine & Cytosine

Where is RNA located?

Inside or outside the nucleus

Four types of RNA

Messenger RNA (mRNA)

Transfer RNA (tRNA)

Ribosomal RNA (rRNA)

Micro RNA