Big Idea 2 – The Chemical Context of Life, Water, Carbon and Macromolecules

Name: _________________________________Date: __________________

Multiple Choice – PART A: Chemistry, Water and Carbon (1pts each; TOTAL = 18 pts) Read each question carefully and choose the BEST answer. WRITE ALL ANSWERS ON THE ANSWER SHEET

____ 1. Which of the following statements about atoms is false?a. Atoms are mostly empty space.b. Protons, neutrons, and electrons have approximately the same mass.c. The nucleus is positively charged due to the presences of protons.d. The further an electron is from the nucleus, the greater its potential energy.

____ 2. The chemical behavior of an atom is determined most directly by the:a. atomic number. c. the number of valence electrons.b. number of energy levels. d. the total number of electrons.

____ 3. If atom “X” contains 14 protons, 13 electrons, and 12 neutrons, and atom “Y” contains 14 protons, 14 electrons, and 12 neutrons, then you conclude that:a. X and Y are isotopes of the same element.b. X and Y are atoms of the same element.c. X and Y both have filled valence shells.d. X is an ion, but Y is not.

____ 4. Van der Waals interactions result whena. a hydrogen atom loses an electron.b. electrons are not symmetrically distributed in a molecule.c. molecules held by ionic bonds react with water.d. two polar covalent bonds react.

____ 5. Which of the following best describes a dynamic chemical equilibrium, as is shown for the reversible chemical reaction below involving the salt barium chloride?

a. Forward and reverse reactions continue with no effect on the concentrations of the reactants and products.

b. Concentrations of products are higher than the concentrations of the reactants.c. Forward and reverse reactions have stopped so that the concentration of the reactants

equals the concentration of the products.d. Reactions reach equilibrium only when all reactants have been converted to products

____ 6. Which of the following drawings best represents a water molecule?

a. c.

b. d.

____ 7. In a lake, mineral nutrients accumulate at the bottom while the amount of dissolved oxygen is greater near the surface. What property of water accounts for the mixing of surface and bottom waters (turnover) during the annual temperature fluctuations as a result of the seasons? a. Individual water molecules move less rapidly as water cools.b. As warm water cools, it reaches its greatest density at 4°C; further cooling of

water (between 4 and 0°C) results in a decrease in density.c. Water changes from liquid to solid at 0°C.d. The distance between water molecules is greater in ice than in liquid form.

____ 8. What is the pH of a solution with a hydrogen ion [H ] concentration of 10 M?a. pH 2 c. pH 6b. pH 4 d. pH 8

____ 9. One liter of a solution of pH 2 has how many more hydrogen ions (H ) than 1 L of a solution of pH 6?a. 3 times more c. 1,000 times moreb. 100 times more d. 10,000 times more

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pH Values of Some Common Substances

Substance pHHydrochloric acid 1.0Sulfuric acid 1.2Tomatoes 4.2Rainwater 6.2Pure water 7.0Sea water 8.5Ammonium chloride 11.1Sodium hydroxide 13.0

____ 10. According to the pH values in the above table, the solution which has as many hydrogen ions (H+) as hydroxide ions (OH-) isa. hydrochloric acid c. sodium hydroxideb. pure water d. sea water

____ 11. The weakest acid listed in the above table isa. hydrochloric acid c. rainwaterb. tomatoes d. pure water

____ 12. A mole of table sugar and a mole of vitamin C are equal in theira. mass in daltons. c. number of molecules.b. mass in grams. d. number of atoms.

____ 13. Three of the following illustrations depict different structural isomers of the organic compound with the molecular formula . For clarity, only the carbon skeletons are shown; hydrogen atoms that would be attached to the carbons have been omitted. Which one is NOT a structural isomer of this compound?

a. c.

b. d.

____ 14. Based on the five molecules displayed above (A-E), which one(s) contain(s) a carbonyl group?a. A c. Db. B and C d. E

____ 15. Based on the five molecules displayed above (A-E), which one(s) is (are) considered an organic acid?a. A c. Db. B and C d. E

____ 16. One of the buffers that contribute to pH stability in human blood is carbonic acid ( ). Carbonic acid is a weak acid that dissociates into a bicarbonate ion (HCO -) and a hydrogen ion (H+) according to the following chemical equation:

H2CO3 <--> HCO3- + H+

If the pH of the blood drops, one would expecta. the concentration of the hydroxide ion (OH-) to decrease.b. the concentration of the hydroxide ion (OH-) to increase.c. the H2CO3 to act as an acid and release H+ with the formation of HCO3

-.d. the HCO3

- to act as a base and remove excess H+ with the formation of H2CO3.

____ 17. Why are hydrocarbons insoluble in water?a. The majority of their bonds are polar covalent carbon-to-hydrogen linkages.b. The majority of their bonds are nonpolar covalent carbon-to-carbon linkages.c. They are hydrophilic.d. They exhibit considerable molecular complexity and diversity.

____ 18. Research indicates that Albuterol, a drug used to relax bronchial muscles, improving airflow and thus offering relief from asthma, consists only of one enantiomer, the R-form. Why is it important for this drug to consist of only one enantiomeric form, rather than a mixture of enantiomers?a. Different enantiomers may have different or opposite physiological effects.b. It is impossible to synthesize mixtures of enantiomers.c. It is much less expensive to synthesize one enantiomer at a time.d. Albuterol is an example of a compound for which only one enantiomer exists.

Multiple Choice – PART B: Macromolecules Read each question carefully and choose the BEST answer. WRITE ALL ANSWERS ON THE ANSWER SHEET

____ 1.The process illustrated in the picture on the right is called:

a. condensationb. denaturationc. hydrolysisd. polymerization

____ 2. The products of the process in the picture abovea. store amino acids.b. supply cells with energy and carbon skeletons.c. function as hormones.d. speed up chemical reactions.

____ 3. The molecule depicted in the above diagram is aa. polynucleotide c. polysaccharide

b. lipid d. polypeptide

____ 4. Each organism is uniquely adapted to its environment even at the molecular level. Human fats are about 3% polyunsaturated while that of cod, a fish living in cold ocean waters, is approximately 50% polyunsaturated. Which of the following contributes to the cod’s ability to survive in extremely cold waters? a. Unsaturated fats act as hormones activating genes for proteins that act as

insulators.b. Unsaturated fats dissolve in the aqueous portions of cells acting like antifreeze and

slow the formation of ice crystals.c. Unsaturated fats remain fluid at lower temperatures than saturated fats due to their

shape.d. Unsaturated fats can be assembled into thicker cell membranes providing

additional insulation against the cold

____ 5. Symbiotic protists in the gut of termites can hydrolyze the cellulose in wood. What molecule then becomes available to both host and symbiont?a. glucose c. glycerol and fatty acidb. glucose and fructose d. nucleotides

____ 6.What i What is the structure shown in the

picture on the right?a. cholesterolb. DNAc. hemoglobind. glycogen

____ 7. Molecular chaperones are proteins that mediate the folding process of:a. other proteins. c. lipids.b. amino acids. d. DNA.

____ 8. The structural level of a protein least affected by a disruption in hydrogen bonding is thea. primary level. c. tertiary level.b. secondary level. d. quaternary level.

____ 9.

The ester bond located within the molecule on the right is labeled:

a. Ab. B.c. C.d. D.

____ 10. The molecule above isa. saturated and liquid at room temperature.b. unsaturated and liquid at room temperature.c. saturated and solid at room temperature.d. unsaturated and solid at room temperature.

____ 11. The diagram above displays six different amino acids (1-6). Which R groups are considered to be both hydrophobic and nonpolar?a. 1 and 3 c. 3 and 6b. 2 and 4 d. 4 and 2

____ 12. Which of the following statements best summarizes the structural differences between DNA and RNA?a. RNA is a protein, whereas DNA is a nucleic acid.b. DNA is a protein, whereas RNA is a nucleic acid.c. DNA nucleotides contain a different sugar than RNA nucleotides.d. RNA is a double helix, but DNA is single-stranded.

____ 13.

[this region is outside the cell]

[this region is inside the cell]

The bilayer structure in the left figure represents a portion of a cell membrane and is composed of

a. structural proteins.b. polysaccharides.c. triacylglycerols (triglycerides).d. phospholipids.

____ 14. The bilayer structure in the above figure is maintained becausea. of hydrogen bonding between the tails.b. of van der Waals forces between the heads.c. the tails are nonpolar and the heads are polar.d. the tails are hydrophilic and the heads are hydrophobic.

____ 15. Which of the following are storage polysaccharides?a. cellulose and chitin c. cholesterol and triacyglycerolb. glucose and sucrose d. glycogen and starch

____ 16.

Which arrow within the cartoon on the right is pointing towards van der Waals forces?

a. Ab. Bc. Cd. D

____ 17. Humans can digest starch but not cellulose becausea. the monomer of starch is glucose, while the monomer of cellulose is galactose.b. humans have enzymes that can hydrolyze the ester linkages of starch but not the

phosphodiester linkages of cellulose.c. humans have enzymes that can hydrolyze the alpha () glycosidic linkages of

starch but not the beta () glycosidic linkages of cellulose.

d. humans harbor starch-digesting bacteria in the digestive tract.

____ 18. What is the type of bond that forms between monomers thereby joining them into polymers?a. hydrogen c. covalentb. ionic d. peptide

____ 19. Which of the following best describes the flow of information in eukaryotic cells?a.b.c.d.

____ 20.The structure displayed in the picture on the right shows the

a. 1-4 linkage of the glucose monomers of starch.b. 1-4 linkage of the glucose monomers of cellulose.c. double helical structure of a DNA molecule.d. helix secondary structure of a polypeptide.

____ 21. All lipids a. are made from glycerol and fatty acids. c. are polymers.b. contain nitrogen. d. do not dissolve well in water.

____ 22. In the structural formula above the peptide bond is labeleda. A c. Cb. B d. D

____ 23. What happens to the shape and function of a protein if one of the amino acids is replaced with a different type of amino acid? a. The protein's quaternary structure will be damaged.b. The protein will not change; several amino acids must be altered to have any effect

on protein function.c. The protein will always denature and become entirely nonfunctional.d. Depending on the chemical nature of the amino acid the protein may lose its

function or there may be no measurable effect on the protein’s function.

____ 24. Which protein is mismatched to its function?a. antibody - protection for invading microoganismsb. keratin - structural support, ex. hairc. enzymes - transport oxygend. actin and myosin - muscle contraction

____ 25. A new organism is discovered in Indonesia. Scientists there determine that the polypeptide sequence of hemoglobin from the new organism has 72 amino acid differences from humans, 65 differences from a gibbon, 49 differences from a rat, and 5 differences from a frog. These data suggest that the new organism a. is more closely related to humans than to frogs.b. is more closely related to humans than to rats.c. may have evolved from gibbons but not rats.d. is more closely related to frogs than to humans.

____ 26. At a cooking demonstration, the speaker’s grand finale was sautéing mealworm (insect larvae) in butter and serving them to the audience. They were crunchy (like popcorn hulls) because their exoskeletons contain the polysaccharidea. collagen c. celluloseb. chitin d. glycogen

____ 27. There are 20 different amino acids. What makes one amino acid different from another?a. different carboxyl groups attached to an alpha () carbonb. different amino groups attached to an alpha () carbonc. different side chains (R groups) attached to an alpha () carbond. different alpha () carbons

____ 28. Lactose, a sugar in milk, is composed of a glucose molecule bonded to a galactose molecule. How is lactose classified?a. as a pentose c. as a disaccharideb. as a monosaccharide d. as a polysaccharide

ANSWER SHEET – Big Idea 2 Exam on The Chemical Context of Life, Water, Carbon and Macromolecules

Part A

1. __b___2. __c___3. __d___4. __b___5. __a___6. __a___7. __b___8. __d___9. __d___10. _b___11. _c___12. _c___13. _c___14. _b___15. __c__16. _d___17. _b___18. _a___

Part B

1. __c___2. __b___3. __a___4. __c___5. __a___6. __a___7. __a___8. __a___9. __b___10. _c____11. _c____12. _c____13. __d___14. __c___

Part B

15. __d___16. __b___17. __c___18. __c___19. __a___20. __d___21. __d___22. __c___23. __d___24. __c___25. __d___26. __b__27. __c___28. __c___