Ch. 2 Biology study guide

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

protons and electrons

What event changes an atom into an ion?

the gain or loss of one or more electrons

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

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

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

the rearrangement of electrons to break or form chemical bonds

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

an amino group and a carboxyl group

Amino acids are named after two of their functional groups: the amino group (NH2), which acts like a base, and the carboxyl group (COOH), which acts like an acid. Amino acids also contain a third functional group, often called the R group. In alanine, the R group is a methyl group (CH3). In serine, the R group is a methyl alcohol (-CH2OH). What functional groups will be joined together if alanine and serine molecules combine to form a single molecule?

Human blood has a pH of 7.4. How do buffers in the blood affect the pH?

Buffers prevent small amounts of acid or base from changing the pH of blood.

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

Enzymes decrease the activation energy of the reaction.

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 decreases the activation energy.

Move the protons and neutrons to a small space in the center.

Lance draws the following model of a carbon atom. Which change to the model would improve its accuracy?

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 are polar.

the chemical structure of the R group in the molecule

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?

Starch is a polymer made of glucose monomers.

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

How do both the similarity and differences among amino acids allow them to form macromolecules with a wide variety of properties?

The presence of amino groups and carboxyl groups allow any combination of amino acids to join together to form a polypeptide. The R groups differ among amino acids, and they determine the properties of the polypeptide or protein.

Carbonic anhydrase is found in the bloodstream of the human body. The bloodstream is usually at a temperature of 37°C. How might an increase in a person's body temperature affect the function of carbonic anhydrase and other enzymes in the body? Be sure to explain any effects on the enzyme itself and the reaction that it catalyzes.

The shape of the enzyme is essential for binding the two substrates and positioning them properly to react and form carbonic acid. Changes to the shape therefore reduce the effectiveness of the enzyme.

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.

covalent bonds formed by shared electrons between atoms

Water covers most of Earth's surface. The diagram shows the structure of a water molecule. What allows the three atoms in a water molecule to stay together?

How does the structure of the water molecule help explain the ability of water to form beads on the wax?

Water is a polar molecule, meaning it has a positive and negative end. The polarity allows multiple hydrogen bonds to form among adjacent water molecules. The hydrogen bonds attract water molecules to one another, and account for the ability of water molecules to adhere, or stick together, such as by forming beads.

Which of these molecular structures could be found in a lipid, but not in a carbohydrate, protein, or nucleic acid?

a long chain made only of carbon and hydrogen atoms

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.

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 described above are MOST USEFUL for explaining which of these functions of lipids in organisms?

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

Which type of macromolecule has the function of storing and transmitting hereditary or genetic information?

nucleic acid

Choose words to complete the sentence Two amino acids unite by forming a(n) (oxygen / hydrogen / peptide / ionic) bond between them and releasing a molecule of (oxygen, carbon dioxide/ hydrogen / water). The union of many amino acids forms a macromolecule called a (protein / nucleic acid / carbohydrate/ lipid).

peptide, water, protein

A scientist is studying two isotopes of sodium, labeled A and B. In Isotope A, each of the atoms has 11 protons, 12 neutrons, and 11 electrons. What could be the atomic structure of Isotope B?

11 protons, 13 neutrons, and 11 electrons