Chemical Basis of Biology — Practice Quiz

A Biology cheat sheet for Chemical Basis of Biology — every key formula with its symbols defined — plus a medium-level practice quiz to test recall.

Formulas & key concepts

The basic unit of matter.

Atom

The center of an atom, which contains the protons and neutrons.

Nucleus

A negatively charged particle; located in the space surrounding the nucleus.

Electron

A pure substance that consists entirely of one type of atom.

Element

One of several forms of a single element, each of which contains the same number of protons but different numbers of neutrons.

Isotope

A substance formed by the chemical combination of two or more elements in definite proportions.

Compound

A chemical bond formed when one or more electrons are transferred from one atom to another.

Ionic Bond

A type of bond between atoms in which the electrons are shared.

Covalent Bond

The smallest unit of most compounds that displays all the properties of that compound.

Molecule

The attraction between molecules of the same substance.

Cohesion

The force of attraction between different kinds of molecules.

Adhesion

A type of mixture in which all the components are evenly distributed.

Solution

A mixture of water and nondissolved material.

Suspension

A compound that releases hydrogen ions (H+) in solution; a solution with a pH of less than 7.

Acid

A compound that releases hydroxide ions (OH–) in solution; a solution with a pH of more than 7.

Base

A compound that prevents sharp, sudden changes in pH.

Buffer

A scale ranging from 0 to 14 that measures the approximate concentration of hydrogen ions of a substance.

pH Scale

A biological macromolecule in which the ratio of carbon to hydrogen to oxygen is 1:2:1; serves as energy sources and structural support.

Carbohydrate

A class of macromolecules that are nonpolar and insoluble in water (fats, oils, waxes, steroids).

Lipid

A biological macromolecule composed of one or more chains of amino acids.

Protein

A biological macromolecule that carries the genetic information of a cell (DNA and RNA).

Nucleic Acid

A monomer of a protein.

Amino Acid

A monomer of nucleic acids; contains a pentose sugar, a phosphate group, and a nitrogenous base.

Nucleotide

A catalyst in a biochemical reaction that is usually a complex or conjugated protein.

Enzyme

Practice quiz

  1. Which subatomic particle is negatively charged and orbits the nucleus of an atom?

    • Proton
    • Neutron
    • Electron
    • Nucleus

    Answer: Electron

  2. Two atoms are identified as isotopes of the same element. Which of the following must be true about them?

    • They have the same number of neutrons but different numbers of protons.
    • They have the same number of protons but different numbers of neutrons.
    • They have different numbers of both protons and neutrons.
    • They have the same total number of protons and neutrons.

    Answer: They have the same number of protons but different numbers of neutrons.

  3. The smallest unit of water ($H_2O$) that still displays all the properties of water is called a:

    • Atom
    • Element
    • Molecule
    • Compound

    Answer: Molecule

  4. Which type of chemical bond involves the sharing of electrons between atoms?

    • Ionic bond
    • Hydrogen bond
    • Covalent bond
    • Metallic bond

    Answer: Covalent bond

  5. The phenomenon where water molecules are attracted to other water molecules is known as:

    • Adhesion
    • Cohesion
    • Capillary action
    • Surface tension

    Answer: Cohesion

  6. A solution with a $pH$ of $2$ would be classified as a(n):

    • Strong base
    • Weak base
    • Acid
    • Neutral solution

    Answer: Acid

  7. What is the primary function of a buffer in a biological system?

    • To increase the rate of chemical reactions.
    • To prevent sharp, sudden changes in $pH$.
    • To dissolve nonpolar substances.
    • To store genetic information.

    Answer: To prevent sharp, sudden changes in $pH$.

  8. Which type of macromolecule is primarily responsible for carrying the genetic information of a cell?

    • Carbohydrate
    • Lipid
    • Protein
    • Nucleic Acid

    Answer: Nucleic Acid

  9. Amino acids are the monomers that make up which larger biological macromolecule?

    • Lipids
    • Carbohydrates
    • Proteins
    • Nucleic Acids

    Answer: Proteins

  10. A biological catalyst that speeds up biochemical reactions, typically a protein, is known as a(n):

    • Hormone
    • Enzyme
    • Vitamin
    • Lipid

    Answer: Enzyme

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