Biology Test 1 Chapter 3

Chemists often represent the structure of atoms using p, n, and e to indicate the number of protons, neutrons, and electrons. Which atom would have an atomic weight of 30? a. 15 p, 15 n, 15 e c. 15 p, 0 n, 15 e b. 10 p, 10 n, 10 e d. 0p, 15n, 15 e

a. 15 p, 15 n, 15 e

The chemical reaction that represents photosynthesis is 6 H2O --> 6 CO2 --> C6H12O6 --> 6 O2. What are the reactants? a. H2O and CO2 c. H2O and O2 b. C6H12O6 and CO2 d. C6H12O6 and CO2

a. H2O and CO2

Which of the following is likely to participate in ionic bonding? a. Li+ c. He b. H2O d. C6H12O6

a. Li+

When ammonia (NH3) is dissolved in a solution, it accepts hydrogen ions from its surroundings. Ammonia is therefore a. a base. c. a salt. b. an isotope. d. an acid.

a. a base

A solution with a pH of 3 is a. acidic. c. non-polar. b. basic. d. neutral.

a. acidic

In the chemical reaction that forms hydrogen peroxide (H2O2), hydrogen and oxygen share electrons creating ________ bonds between the two atoms. a. covalent c. hydrogen b. peptide d. ionic

a. covalent

Which of the following amino acids begins the construction of all proteins in the human body? a. methionine c. proline b. leucine d. tryptophan

a. methionine

The genetic material found in all living things is made of building blocks called a. nucleotides. c. phospholipids. b. monosaccharides. d. steroids.

a. nucleotides.

Which of the following solutions has the highest concentration of free H+ ions? a. pH 1 c. pH 7 b. pH 4 d. pH 14

a. pH 1

Neighboring water molecules are held together with hydrogen bonds because a. partially negatively charged oxygen atoms and partially positively charged hydrogen atoms on separate water molecules are attracted to one another. b. the hydrogen and oxygen atoms within a single water molecule share electrons equally. c. the oxygen and hydrogen atoms that participate in hydrogen bonding are sharing electons within a single valence shell. d. ionic interactions repel water molecules from hydrophobic oils that may be present in a solution.

a. partially negatively charged oxygen atoms and partially positively charged hydrogen atoms on separate water molecules are attracted to one another.

Macromolecules are typically formed by repetitively adding small monomers together. Which macromolecule is properly matched with the appropriate monomer? a. polypeptide—amino acid c. polysaccharide—nucleotide b. nucleic acid—amino acid d. triglyceride—cholesterol

a. polypeptide—amino acid

A disaccharide consists of two a. sugars. c. fatty acids. b. hydrocarbons. d. amino acids.

a. sugars.

Oil and water do not mix together well because a. water is polar and oil is non-polar. b. only identical molecules of the same chemical can easily mix together. c. water has hydrogen bonds and oil is polar. d. water and oil are covalently bonded together.

a. water is polar and oil is non-polar.

How many different amino acids are used to build proteins? a. 90 c. 19 b. 20 d. 4

b. 20

Based on the water molecule pictured below, which of the labeled areas possesses a partial negative charge? a. A only c. C only b. B only d. A and C **check picture

b. B only

Which of the following explains why ice floats on water? a. The crystal structure of ice is more regular than that seen in liquid water. b. The distance between water molecules in ice is greater than in liquid water. c. The cool temperature of ice reduces the extent of molecular motion relative to liquid water. d. When ice forms, the hydrogen bond in the water molecule becomes non-polar; ice behaves like oil.

b. The distance between water molecules in ice is greater than in liquid water.

Which of the following is a monomer that can be commonly made from components in Earth's atmosphere? a. nucleotides c. triglycerides b. amino acids d. monosaccharides

b. amino acids

The central element found in organic molecules is a. calcium. c. silicon. b. carbon. d. sodium.

b. carbon

Which of the following is an organic compound? a. water (H2O) c. ammonia (NH3) b. methane (CH4) d. carbon dioxide (CO2)

b. methane (CH4)

Nitrogen has seven protons, seven neutrons, and seven electrons. What is the atomic mass of nitrogen? a. 0 c. 14 b. 7 d. 21

c. 14

Which of the following factors explains carbon's prominence in living systems? a. Carbon forms weak reversible bonds. b. Carbon bonds with up to three other atoms. c. Carbon-based molecules can form long chains and rings. d. Carbon does not form small molecules.

c. Carbon-based molecules can form long chains and rings.

Which of the following statements is true of proteins, carbohydrates, and nucleic acids? a. All three are used to store genetic information. b. None of these macromolecules mixes well with water. c. Each of these molecules is built from a common set of monomers. d. All of these molecules are primarily used as energy-storage molecules.

c. Each of these molecules is built from a common set of monomers.

Which of the following distinguishes ionic bonds from covalent bonds? a. Ionic bonds form between the same two elements, whereas covalent bonds form between different elements. b. Ionic bonds hold together compounds that do not dissolve in water, whereas covalent bonds hold together molecules that dissolve in water. c. Ionic bonds hold together oppositely charged atoms, whereas covalent bonds hold together atoms that share electrons. d. Ionic bonds consist of atoms with partial charges, whereas covalent bonds consist of atoms with full positive and negative charges.

c. Ionic bonds hold together oppositely charged atoms, whereas covalent bonds hold together atoms that share electrons.

A group of astronauts returning from outer space studied samples taken from their lunar landing. They found that one of their samples was coated with organic compounds. Which of the following statements must be correct about their samples? a. The compounds must be covered with ammonia (NH3) and water vapor. b. The samples must lack water, but contain DNA. c. The samples must contain carbon atoms. d. The specimen must lack water, pesticides, and added hormones.

c. The samples must contain carbon atoms.

Antibodies are an important class of human proteins that function in immune defense. If scientists fragmented antibodies under laboratory conditions, what chemical building blocks would they recover? a. monosaccharides c. amino acids b. phospholipids d. nitrogenous bases

c. amino acids

In the laboratory you identify protein in a food item that you've tested. Which of the following must the food item also contain? a. glucose c. amino acids b. lipids d. nucleotides

c. amino acids

Carbon, hydrogen, and nitrogen are all examples of a. compounds. c. elements. b. macromolecules. d. amino acids.

c. elements

Individual water molecules orient toward each other because of the ________ bonds that form between them. a. covalent c. hydrogen b. peptide d. ionic

c. hydrogen

In making your morning tea, you drop a sugar cube into some hot water. You stir the mixture but no longer see the sugar cube at the bottom of your mug. Based on your observation of sugar dissolving in hot water, you properly conclude that the sugar is a. hydrophobic. c. hydrophilic. b. non-polar. d. inert.

c. hydrophilic.

Which of the following types of bonds hold hydrogen and oxygen atoms together within an individual water molecule? a. hydrogen bond c. polar covalent bond b. peptide bond d. ionic bond

c. polar covalent bond

The pH scale measures a. the amount of water in a solution. b. the likelihood that a solution will evaporate. c. the concentration of hydrogen ions in a solution. d. the number of atoms found within a molecule.

c. the concentration of hydrogen ions in a solution.

Which of the following pieces of evidence would best demonstrate that a bacterium found on an asteroid originated in outer space? a. the presence of volcanic ash on the outside of the bacterial cell b. the absence of common gases found in Earth's atmosphere c. the presence of right-handed amino acids in the bacterium's proteins d. the absence of hydrogen bonds between water molecules in the bacterial cell

c. the presence of right-handed amino acids in the bacterium's proteins

In living systems, a critical component of many reactions is a. carbon dioxide. c. water. b. calcium. d. hydrogen sulfide.

c. water.

Of the following values, which indicates the most basic pH? a. 5 c. 8 b. 7 d. 10

d. 10

How many atoms are present in a single molecule of C8H10N4O2? a. 4 c. 12 b. 8 d. 24

d. 24

If iodide ions (I-) were dissolved in water, they would be attracted to a. A only c. C only b. B only d. A and C

d. A and C

O2, also termed atmospheric oxygen, is considered to be a molecule but not a compound. Why not? a. It contains no covalent bonds. b. It contains a double covalent bond but not a single covalent bond. c. To be considered a compound there must be a minimum of three atoms; atmospheric oxygen is too small. d. Compounds are defined as molecules constructed from two or more different elements.

d. Compounds are defined as molecules constructed from two or more different elements.

A carwash attendant offers to treat your windshield with a protective agent. This substance coats the glass, causing beads of water to easily roll off during a rain shower. Which of the following must be correct about the protective agent? a. It resists temperature changes well. c. It is a polar substance. b. It must be an acid. d. It must be hydrophobic.

d. It must be hydrophobic.

18. Which of the following is correct about hydrogen bonds? a. Individually, hydrogen bonds are very strong. b. They form between neighboring oxygen atoms. c. They do not involve binding with a hydrogen atom. d. They form due to partial positive and partial negative charges on atoms.

d. They form due to partial positive and partial negative charges on atoms.

In making your morning tea, you drop a sugar cube into the hot water. You stir the mixture but no longer see the sugar cube at the bottom of your mug. In this scenario, the sugar is a. non-polar. c. an acid. b. the solvent. d. a solute.

d. a solute.

After adding a small amount of Solution A to Solution B, the pH of Solution B declines from 8 to 3. Solution A must contain a. a salt. c. water only. b. a base. d. an acid.

d. an acid.

Nucleotides a. are the building blocks of proteins. b. are involved in every chemical reaction in the cell. c. form physical structures such as hair. d. are the building blocks of nucleic acids.

d. are the building blocks of nucleic acids.

Carbon atoms are bound to each other by a. ionic bonds. c. hydrogen bonds. b. polar bonds. d. covalent bonds.

d. covalent bonds.

You are given an unknown substance and asked to determine whether it is polar or non-polar. The easiest way to do this would be to a. determine whether the compound is held together by hydrogen bonds. b. determine the number of electrons in the compound's outer shell. c. mix the compound with an ionic substance to see whether its bonds can withstand the pressure. d. determine whether the compound dissolves in water.

d. determine whether the compound dissolves in water.

An acid is a polar substance that dissolves in water and a. becomes non-polar. b. leaves behind an OH- ion. c. accepts hydrogen ions from the solution. d. donates hydrogen ions to the solution.

d. donates hydrogen ions to the solution.

The subatomic particles that possess a single negative charge and surround the nucleus are the a. isotopes. c. neutrons. b. protons. d. electrons.

d. electrons.

When calcium (Ca++) and chloride (Cl-) interact with one another they bond using ________ bonds. a. hydrogen c. covalent b. peptide d. ionic

d. ionic

When sodium chloride (Na+Cl-) is dissolved in water, the sodium ion a. is attracted to the hydrogen atoms of water molecules. b. is repelled by the oxygen atoms of water molecules. c. is attracted to other sodium ions that are being dissolved. d. is attracted to the oxygen atoms of water molecules.

d. is attracted to the oxygen atoms of water molecules.

Which of the following could be built solely from glucose molecules? a. fatty acids c. oils b. DNA d. starch

d. starch