Chapter 2: The Chemistry of Life

Which two types of particles are present in equal numbers in an atom, but not in an ion?

• protons and electrons

• protons and neutrons

• inner-shell electrons and outer-shell electrons

• protons and inner-shell electrons

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NGSS.HS-PS1-7

The elements sodium and chlorine react to form the chemical compound sodium chloride. How would you predict the properties of sodium chloride compare with those of its constituent elements?

• very different

• similar in most ways, but not identical

• identical in all ways

• an average or mixture of the two elements

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NGSS.HS-PS1-1

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What property of a water molecule allows hydrogen bonds to form among adjacent molecules?

• the strong covalent bonds that hold the oxygen atom to each hydrogen atom

• the ionic bonds that form after the molecule separates into a hydroxide ion (OH–) and hydrogen ion (H+)

• the small size of the two hydrogen atoms compared to the oxygen atom

• the polarity of the molecule, which involves a slightly negative oxygen atom and slightly positive hydrogen atoms

The results of the experiment are MOST USEFUL for explaining which of these functions of lipids in organisms?

• forming a waterproof covering on feathers, leaves, and fruits.

• providing energy for the cell

• allowing water to pass through the cell membrane

• replacing water in dry environments

The results of the experiment MOST STRONGLY support which conclusion about the polarity of lipid molecules?

• Lipid molecules are polar because they mix poorly with liquids, such as water.

• Lipid molecules are polar because they adhere tightly to smooth surfaces, such as paper.

• Lipid molecules are nonpolar because they repel water molecules, which also are nonpolar.

• Lipid molecules are nonpolar because they repel water molecules, which are polar.

Household bleach has a pH between 12 and 13. From this information, which of the following BEST describes the bleach solution?

• The solution is acidic, meaning it has more hydrogen (H⁺) ions than hydroxide (OH⁻) ions.

• The solution is basic, meaning it has fewer hydrogen (H⁺) ions than hydroxide (OH⁻) ions.

• The solution is neutral, meaning it has an equal number of hydrogen (H⁺) ions and hydroxide (OH⁻) ions.

• The solution is a buffer that reacts with solutions containing high concentrations of hydrogen (H⁺) ions.

The diagram shows the structure of starch, a complex carbohydrate. What best describes the relationship between starch and glucose?

• Starch and glucose are reactants that combine to form proteins.

• Starch is a monomer that is used to make glucose.

• Starch is a polymer made of glucose monomers.

• Starch and glucose are reactants that combine to form nucleic acids.

The diagram shows the general structure of an amino acid. Several different amino acids join together to form a protein. How do any two types of amino acids differ from one another?

• the number of amino groups in the molecule

• the number of carboxyl groups in the molecule

• the chemical structure of the R group in the molecule

• the number of chemical bonds formed by the central carbon atom

In a chemical reaction, which event ALWAYS occurs as the reaction proceeds?

• the rearrangement of electrons to break or form chemical bonds

• the release of energy to the environment

• the absorption of energy from the environment

• a change in total mass

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What is the effect of an enzyme on the energy of a chemical reaction?

• Enzymes increase the free energy of the products.

• Enzymes decrease the free energy of the reactants.

• Enzymes decrease the difference in energy between products and reactants.

• Enzymes decrease the activation energy of the reaction.

Tags

NGSS.HS-PS1-4