• All matter is composed of elements, each having one type of atom.
• Atoms react with one another, forming ions, molecules, and compounds.

1. How is an atom organized?
   Answer
2. What are radioactive isotopes and how can they be used for the biological benefit of humans?
   Answer
3. What are the two basic types of bondings between atoms?
   Answer

Essential Study Partner

• Atoms
• Bonds

Art Quiz

• Periodic Table
• Electron Energy Levels

Animation Activities

• Atomic Structure
• Covalent Bond
• Ionic Bond

• The existence of living things is dependent on the characteristics of water.
• The hydrogen ion concentration in water changes when acids or bases are added to water.

1. What characteristics of water help support life?
   Answer
2. How does the hydrogen ion concentration change among water, acids, and bases?
   Answer

Essential Study Partner

• Water
• pH

Art Quiz

• Molecular Structure of Water
• Water as a Solvent
• pH Scale
• Formation of Acid Precipitation

• Macromolecules are polymers that arise when their specific monomers (unit molecules) join together.
• The molecules found in cells are carbohydrates, lipids, proteins, and nucleic acids.

1. What are the four classes of molecules unique to cells?
   Answer
2. What individual subunits make up carbohydrates, fats, proteins, and nucleic acids?
   Answer

Essential Study Partner

• Organic Chemistry

• Carbohydrates function as a ready source of energy in most organisms.
• Glucose is a simple sugar; starch, glycogen, and cellulose are polymers of glucose.
• Cellulose lends structural support to plant cell walls.

1. What is the usual function of carbohydrates in organisms?
   Answer
2. What are some examples of different types of carbohydrates?
   Answer

Essential Study Partner

• Carbohydrates

• Lipids are varied molecules.
• Fats and oils, which function in long-term energy storage, are composed of glycerol and three fatty acids.
• Sex hormones are derived from cholesterol, a complex ring compound.

1. What is the function of fats and oils, and of what are they composed?
   Answer
2. What are the uses of steroids in the body?
   Answer

Essential Study Partner

• Lipids

Art Quiz

• Unsaturated Fat

• Proteins help form structures (e.g., muscles and membranes) and function as enzymes.
• Proteins are polymers of amino acids.

1. What are the major functions of proteins in organisms?
   Answer
2. How do proteins illustrate the principle that the shape of a molecule influences its function?
   Answer

Essential Study Partner

• Proteins

Art Quiz

• Peptide Bonds

• Nucleic acids are polymers of nucleotides.
• Genes are composed of DNA. RNA serves as an intermediary during protein synthesis.

1. What is the function of DNA in cells?
   Answer
2. Howis the function of RNA related to the function of DNA?
   Answer
3. What does it mean to say that DNA is a double helix?
   Answer

Essential Study Partner

• Nucleic Acids

Art Quiz

• DNA Base-Pairing and Hydrogen Bonds