The Chemistry of Life

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

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

What best describes the relationship between starch and glucose?

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

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

• Starch is a polymer made of glucose monomers

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

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

• Enzymes decrease the free energy of the reactants

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

• Enzymes increase the free energy of the products.

• Enzymes decrease the activation energy of the reaction.

What event changes an atom into an ion?

• a chemical reaction that forms a molecule

• the gain or loss of one or more neutrons

• the sharing of electrons with another atom

• the gain or loss of one or more electrons

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

• protons and electrons

• protons and inner-shell electrons

• inner-shell electrons and outer-shell electrons

• protons and neutrons

A team of scientists and engineers is working together to develop a new cleaning product. The team has identified a species of bacteria that gets energy by breaking apart lipids and oils. The team wants to isolate the key substance that the bacteria use for this process, and then adapt the substance for the new cleaning product.

Which macromolecule should the team try to isolate from the bacteria?

• an amino acid that codes for the production of a lipid or oil

• a carbohydrate that is about the same size as a typical lipid or oil molecule

• a lipid or oil that is unique to the bacteria

• a protein that specifically binds lipids or oils

A teacher assigns the following experiment to a class. Draw an outline of a bird's feather, and color one half of the outline with a thick coat from a wax crayon. Leave the other half uncolored. Next, sprinkle a few drops of water on both halves of the feather. You will observe that the water soaks into the plain paper. The waxy coat, however, allows the paper to remain dry. Water forms tiny beads on top of the wax instead of soaking through it.

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

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

• 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 are polar.

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

• the rearrangement of electrons to break or form chemical bonds

• a change in total mass

• the release of energy to the environment

• the absorption of energy from the environment

Tags

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?

• similar in most ways, but not identical

• an average or mixture of the two elements

• very different

• identical in all ways

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

The enzyme carbonic anhydrase is a protein that binds to two small molecules: water and carbon dioxide. By holding the two molecules in the proper position, the enzyme allows the two molecules to react to form a product, carbonic acid. The enzyme then releases the product and becomes available to catalyze the same reaction once again.

How does carbonic anhydrase change the reaction between carbon dioxide and water?

• It increases the total energy released.

• It alters the structure of the product

• It decreases the activation energy.

• It decreases the total mass of the system.