Unit 3 Review Questions

AP Biology

1. What was the first organic molecule to be synthesized in the laboratory?

• A. ammonium cyanate• B. hydrogen cyanide• C. urea• D. acetic acid• E. methane

2. Carbon is an unusual atom in that it can form multiple bonds. Which statement is NOT true?

a) A carbon-to-carbon cis double bond is the type found in nature and is associated with cardiovascular health.

b) A carbon-to-carbon trans double bond is made artificially in food processing and is associated with poor cardiovascular health.

c) Multiple carbon-to-carbon double bonds located near each other can absorb light, so they are found in molecules in the eye or in chloroplasts.

d) Multiple carbon-to-carbon bonds are stronger than single bonds.

e) Saturated fats are those that have a carbon-to-carbon double bond and are associated with good health.

3. What type of chemical bond joins a functional group to the carbon skeleton of a large molecule?

A. covalent bond

B. hydrogen bond

C. ionic bond

D. double bond

E. disulfide bond

4. Which of the following is NOT one of the seven functional groups found in biological molecules?

A. amino

B. hydroxyl

C. carboxyl

D. cyanate

E. phosphate

5. Which functional group behaves as a weak acid in organic molecules?

A. amino

B. carboxyl

C. carbonyl

D. sulfhydryl

E. hydroxyl

6. Which functional group behaves as a weak base in organic molecules?

A. amino

B. carboxyl

C. carbonyl

D. sulfhydryl

E. hydroxyl

7. Which type of molecule always contains phosphate groups?

A. carbohydrates

B. lipids

C. proteins

D. nucleic acids

E. none of the above

8. What type of isomer is propanal compared to acetone?

A. cis-trans isomer

B. structural isomer

C. enantiomer

D. none of the above; these are not isomers

9. Which type of molecule may contain sulfhydryl groups?

A. carbohydrateB. lipidC. proteinD. nucleic acidE. all of the above

10. Which functional group is best known for its ability to change the shape of a molecule without affecting its

reactivity?

A. aminoB. carboxylC. sulfhydrylD. phosphateE. methyl

11. The table below gives the molar ratios of some of the products from Stanley Miller’s

abiotic synthesis of organic molecules experiment. What is the molar ratio of serine?

A. 1 mole of serine per mole of glycine

B. 3.0 x 102 moles of serine per mole of glycine

C. 3.0 x 102 moles of glycine per mole of serine

D. 1 mole of serine per 3.0 x 102 moles of glycine

12. The table below gives the molar ratios of some of the products from Stanley Miller’s abiotic synthesis of organic molecules experiment. Which amino acid is

present in higher amounts than glycine?

A. serine

B. methionine

C. alanine

D. serine and methionine

13. The synthetic atmosphere in this experiment contained H2S instead of water vapor. Which of

these amino acids could not have been produced in Miller’s original abiotic

synthesis experiment?

A. serine

B. methionine

C. alanine

D. glycine

14. What are the four emergent properties of water that are important for life?

A. cohesion, expansion upon freezing, high heat of evaporation, capillarity

B. cohesion, moderation of temperature, expansion upon freezing, solvent properties

C. moderation of temperature, solvent properties, high surface tension, capillarity

D. heat of vaporization, high specific heat, high surface tension, capillarity

E. polarity, hydrogen bonding, high specific heat, high surface tension

15. Water shows high cohesion and surface tension and can absorb large

amounts of heat because of large numbers of which of the following bonds between water molecules?

A. strong ionic bondsB. nonpolar covalent bondsC. polar covalent bondsD. hydrogen bondsE. weak ionic bonds

16. Water has an unusually high specific heat. What does this mean?

A. At its boiling point, water changes from liquid to vapor.

B. More heat is required to raise the temperature of water.

C. Ice floats in liquid water.D. Salt water freezes at a lower

temperature than pure water.E. Floating ice can insulate bodies of water.

17. Surfactants reduce surface tension of a liquid. Which of the

following would result if water was treated with surfactants?A. Surfactant-treated water droplets

would form a thin film instead of beading on a waxed surface.

B. Surfactant-treated water would form smaller droplets when dripping from a sink.

C. Water striders would sink.D. All of the above would occur.E. Only A and C would occur.

18. In a glass of old-fashioned lemonade, which is the solvent?

A. lemon juiceB. sugarC. waterD. lemonade mixtureE. ice

19. Skin is coated with a hydrophobic glycolipid. What would happen if this was not present?

A. Water would be lost from skin cells more quickly.

B. Skin would swell when swimming.C. Skin would wrinkle more.D. A and B onlyE. A, B, and C

20. Compared to an acidic solution at pH 5, a basic solution at pH 8 has

A. 1,000 times more hydrogen ions.B. 1,000 times less hydrogen ions.C. 100 times less hydrogen ions.D. the same number of hydrogen ions

but more hydroxide ions.E. 100 times less hydroxide ions.

21. Which of the following acts as a pH buffer in blood?

A.carbonic acidB.bicarbonate ionC.carbonate ionD.hydroxide ionE. A and B

22. Scientists predict that acidification of the ocean will lower the concentration of dissolved carbonate ions (CO3

2), which are

required for coral reef calcification. To test this hypothesis, what would

be the independent variable?

A. ocean pHB. the rate of calcificationC. the amount of atmospheric CO2

D. time

E. volume of seawater

23. Based on this graph, what is the relationship between carbonate ion concentration and calcification rate?

A. As the acidity of the seawater increased, the rate of calcification decreased.

B. As the rate of calcification increased, the concentration of carbonate ions increased.

C. As the concentration of carbonate ions increased, the rate of calcification decreased.

D. As the concentration of carbonate ions increased, the rate of calcification increased.

24. If the seawater carbonate ion concentration is 250 µmol/kg, what is the approximate rate of calcification

according to this graph? A. 5 mmol CaCO3 per m

2 per day

B. 10 mmol CaCO3 per m

2 per day

C. 15 mmol CaCO3 per m

2 per day

D. 20 mmol CaCO3 per m

2 per day

25. Polymers are made of connected monomer subunits that are joined by what type of bonds?

A. ionic bondsB. covalent bonds C. hydrogen bondsD. hydrophobic bonds

26. Silicon (atomic number 14, atomic weight 28) is in the same column as carbon in the periodic table of the

elements (group IV). Why isn’t life on Earth based on silicon, instead of carbon?

A. Silicon is far more rare in the Earth’s crust than carbon.

B. Silicon cannot form polar covalent bonds with oxygen.

C. Silicon has a different valence than carbon.D. Silicon compounds often have very

different physico-chemical properties than the analogous carbon compounds.

27. Which polysaccharide has the greatest number of branches?

A. celluloseB. chitinC. amyloseD. amylopectinE. glycogen

28. A polysaccharide you are studying is found to contain unbranched β glucose molecules and cannot be

digested by humans. Which polysaccharide are you studying?

A. celluloseB. DNAC. chitinD. starchE. glycogen

29. Lipids cannot be considered polymers because

A. they contain polar covalent bonds.B. their structure includes carbon

rings.C. they can be artificially created.D. their monomers are connected via

ionic bonds.E. they are not composed of monomer

subunits.

30. All lipids

A. are made from glycerol and fatty acids.

B. contain nitrogen.C. have low energy content.D. are acidic when mixed with water.E. do not dissolve well in water.

31. Sickle-cell disease is caused by a mutation in the -hemoglobin gene that changes a charged amino acid, glutamic acid, to valine, a hydrophobic amino acid. Where in the protein would you expect to

find glutamic acid?

A. on the exterior surface of the proteinB. in the interior of the protein, away

from waterC. at the active site, binding oxygenD. at the heme-binding site

32. Which is not a function of proteins?

A. help make up membranesB. carry the code for translation from

the nucleus to the ribosomeC. bind to hormones (hormone

receptor)D. can be hormonesE. speed chemical reactions

33. How does RNA differ from DNA?

A. DNA encodes hereditary information; RNA does not.

B. DNA forms duplexes; RNA does not.C. DNA contains thymine; RNA

contains uracil.D. all of the above

34. DNA and polypeptide sequences from closely related species are more similar to each other than sequences from more distantly related species. For the remaining questions, you will look at amino acid sequence data for the β polypeptide chain of hemoglobin, often called β-globin. You will then interpret the data to hypothesize whether the monkey or the gibbon is more closely related to humans.

In the alignment shown below, the letters give the sequences of the 146 amino acids in β-globin from humans, rhesus monkeys, and gibbons. Because a complete sequence would not fit on one line, the sequences are broken into segments. The sequences for the three different species are aligned so that you can compare them easily. For example, you can see that, for all three species, the first amino acid is “V” (valine) and the 146th amino acid is “H” (histidine).

Scan along the aligned sequences, letter by letter, noting any positions where the amino acids in the monkey or gibbon sequences do not match the human sequence.

34. How many amino acids differ between the monkey and the human sequences?

A. 2B. 6C. 8D. 10

35. How many amino acids differ between the gibbon and the human sequences?

A. 1B. 2C. 6D. 8

36. What percent of monkey β-globin amino acids are identical to the human sequence? (This is called the percent

identity between the monkey and human β-globin sequences. Note: 146 amino

acids total.)A. 5.48%B. 94.5%C. 95.9%D. 98.6%

37. Based on the β-globin alignment, identify the best hypothesis about how humans are related to

monkeys and gibbons.

A. Monkeys are more closely related to humans than gibbons are because monkeys’ β-globin sequence has the lower percent identity with humans.

B. Both monkeys and gibbons are equally unrelated to humans because neither monkeys nor gibbons have the exact same β-globin sequence as humans.

C. Both monkeys and gibbons are equally related to humans because they both have less than a 10% difference in β-globin sequence with humans.

D. Gibbons are more closely related to humans than monkeys are because the gibbon β-globin sequence is a closer match with the human sequence.

38. What other evidence could you use to analyze evolutionary relatedness among gibbons,

monkeys, and humans?

A. the amino acid sequences of other proteins from gibbons, monkeys, and humans

B. the amount of habitat overlap among gibbons, monkeys, and humans

C. the β-globin amino acid sequence from gorillas

D. the frequency of albinism (mutants that lack hair and skin pigment) in populations of gibbons, monkeys, and humans