Test : Macromolecules and Enzymes

Name:

There are 35 questions on this test worth 2 points each for a total of 70 points. The in-class essays will be worth an additional 20 points (10 points for two essays) for a total of 90 points for this test.

Some answer choices require you to identify multiple “correct” answers in the form of “some or all of the above”. Read each question and ALL possible answers carefully before making your choice.

Water is a polar molecule. This means that:

a.	electrons are unequally distributed throughout the molecule, causing oxygen to have a partially negative charge and the hydrogens to have a partially positive charge.
b.	electrons are unequally distributed throughout the molecule, causing oxygen to have a partially positive charge and the hydrogens to have a partially negative charge.
c.	water is a charged molecule, allowing it to interact with other ions and charged substances.
d.	water is a charged molecule that only interacts with other polar molecules.
e.	both (a) and (c) are true statements.

A hydrogen bond is

a.	a sharing of a pair of electrons between a hydrogen and an oxygen nucleus.
b.	a sharing of a pair of electrons between a hydrogen nucleus and either an oxygen or a nitrogen nucleus.
c.	an attractive force that involves a partially positive hydrogen atom and a partially negative oxygen or a nitrogen atom.
d.	none of these
e.	all of these

Which of the following statements is false about the various chemical bonds significant to macromolecular structure?

a.	Covalent bonds are the strongest bond relative to H-bonds, ionic interactions, and hydrophobic interactions.
b.	Covalent bonds are responsible for the links between individual monomers building long polymers.
c.	Polar and nonpolar interactions contribute to the orientation of phospholipids in a cell membrane (phospholipid bilayer).
d.	Ionic interactions remain stable when temperature increases.
e.	Ionic interactions contribute to the three-dimensional structure of a protein.

The formation of large molecules from small repeating units is known as what kind of reaction?

a.	polar interaction
b.	dissolving
c.	dehydration synthesis
d.	hydrolysis
e.	All of the above.

Which of the following is not a proper monomer:polymer pair?

a.	Amino acid : Protein
b.	Fats : Oils
c.	Monosaccharide : Polysaccharide
d.	Glucose : Cellulose
e.	All of the above relationships are valid.

Although both cellulose and starch are made of glucose, the two polysaccharides have significantly different structures and functions because:

a.	They are made of two different glucose isomers, resulting in a different structure forming the two polymers.
b.	The same glucose molecule is bonded differently in the two polymers.
c.	They have different sidechains coming off the polysaccharide backbone.
d.	Glucose can either be bonded horizontally or vertically.
e.	None of the above choices are correct.

Which best describes the composition of a phospholipid molecule?

a.	One glycerol and three fatty acids.
b.	One glycerol, two fatty acids, and a phosphate group.
c.	Ring-shaped carbon structure with fatty acids.
d.	One glycerol and two fatty acids.
e.	A ring shaped structure with carbons and oxygens.

Triglycerides are

a.	carbohydrates.
b.	enzymes.
c.	proteins.
d.	fats.
e.	none of the above.

Which statements are true about saturated fatty acids?

a.	Saturated fatty acids have carbon atoms double bonded to another carbon atom.
b.	Triglycerides high in saturated fatty acids are normally liquids at room temperature.
c.	The carbon atoms in a saturated fatty acid carries its maximum capacity of hydrogen atoms.
d.	Both (a) and (c) are true.
e.	All of the above are true.

10.

A protein's function is dependent on its:

a.	Temperature
b.	Size
c.	Weight
d.	Structure
e.	All of the above

11.

Which of the following is able to denature a protein?

a.	Changes in pH.
b.	Increase in temperature.
c.	High salt concentration.
d.	Excess ions in solution.
e.	All of the above.

12.

Which of the following statements is false about the primary structure of proteins?

a.	It is the linear sequence of amino acids connected to each other through peptide bonds.
b.	It is the interaction of amino acids sidechains that folds the protein into its 3-dimensional structure.
c.	It is ultimately responsible for determining the final structure of a protein.
d.	It is hard to break because it is held together with covalent bonds.
e.	In our cells, it is made up of the combination of 20 different amino acids.

13.

The secondary structure of proteins is:

a.	the result of the interaction of the protein backbone with adjacent backbones.
b.	the result of the interaction of amino acid sidechains.
c.	held together by weak interactions.
d.	both (a) and (c) are correct.
e.	both (b) and (c) are correct.

14.

You tested a carbohydrate solution with Benedict's solution and you observed a positive result. Which of the following statements are true?

a.	The color of the solution turned from blue to a bright orange after heating in a water bath.
b.	You can conclude that the solution contains a monosaccharide.
c.	You can conclude that the solution contains a polysaccharide.
d.	The solution may contain glucose.
e.	(a), (b), and (d) are all true.

15.

Recall how you were able to observe the effects of salivary amylase and catalase in the classroom. Which of the following statements is false?

a.	Salivary amylase breaks down polysaccharides, a macromolecule that can be identified using IKI.
b.	Since the salivary amylase in your saliva broke down the starch on the starch plate, staining with IKI produced a “negative” zone that did not stain black.
c.	Catalase breaks down hydrogen peroxide, releasing oxygen gas and water.
d.	When catalase was cooled to low temperatures using ice, less oxygen was produced because there was probably less kinetic energy available for the enzyme to be functional.
e.	When catalase was heated to high temperatures (80 degrees Celsius), the increase in kinetic energy caused an increase in enzyme’s activity.

Answer the following questions based on the diagram below:

16.

The small ion above (seen surrounded by water in the top left) must be:

a.	a positively charged ion.
b.	a negatively charged ion.
c.	a nonpolar molecule.
d.	a neutral (uncharged) atom.
e.	There is not enough information on the diagram to determine.

The following four diagrams show the structures of different molecules. Answer the following questions based on your ability to identify them.

17.

Which diagram represents the monomer units of proteins?

a.	1.
b.	2.
c.	3.
d.	4.
e.	Both (2) and (4)

18.

Which diagram shows a structural isomer of cellulose?

a.	1.
b.	2.
c.	3.
d.	4.
e.	None of the above.

19.

Which macromolecule is best associated with the terms saturated and unsaturated?

a.	1.
b.	2.
c.	3.
d.	4.
e.	All molecules have saturated and unsaturated structures.

Identify the diagram below and answer the following questions.

20.

This molecule is a _____, which belongs to the _____ group of macromolecules.

a.	amino acid... protein.
b.	phospholipid... polysaccharide.
c.	phospholipid... lipid.
d.	monomer... polymer.
e.	monosaccharide... polysaccharide.

21.

“The predicted nature of the labeled area _____ is _____ due to _____.” Which of the following accurately complete this statement?

a.	1... polar... due to the large phosphate group with multiple oxygen atoms.
b.	2... nonpolar... the large number of C-H bonds that tend to share electrons evenly.
c.	4... hydrophilic... double bonds within the fatty acid tail.
d.	Both (a) and (b)
e.	All of the above.

The following diagram shows a sequence of a reaction. The numbers 1through 4 identify different parts of the overall structure.

22.

Numbers 1-4 highlight different parts of the structures show in the diagram. Which part is directly involved in the tertiary interactions (tertiary structure) that determine the three dimensional structure of this macromolecule?

a.	1.
b.	2.
c.	3.
d.	4.
e.	Both (1) and (2)

23.

Which of the following is true?

a.	2 is the protein backbone.
b.	3 is a peptide bond, a type of covalent bond.
c.	4 is the monomer unit of a protein.
d.	Only (a) and (c) are true.
e.	All of the above are true.

The following diagram shows the different levels of structure for a type of macromolecule. Answer the questions based on your understanding of how these structures are maintained.

24.

Which diagram above, 1-5, represents the interactions of multiple polypeptides?

a.	1
b.	2
c.	3
d.	4
e.	5

25.

Which of the following levels of structure is most likely NOT to be affected by high temperature, changes in salt concentration, and changes in pH?

a.	1
b.	2
c.	3
d.	4
e.	5

Answer the following questions based on the diagram below:

26.

If the protein above is placed into boiling water, which of the following will most likely happen?

a.	The protein will remain functional.
b.	The polar sidechains of the protein will interact with the water and maintain the shape of the protein.
c.	All four chemical bonds shown above will break.
d.	All chemical bonds except the bond labeled (2) will break.
e.	All chemical bonds except the bond labeled (3) will break.

27.

Which of the following statements are true regarding the characteristics of a protein shown in this diagram?

a.	These interactions are collectively called tertiary interactions.
b.	These interactions occur between amino acid sidechains on a single polypeptide.
c.	Once made, these interactions are strong enough to allow the protein to keep its shape permanently.
d.	Both (a) and (b) are true.
e.	All of the above are true.

Answer the following questions based on the diagram below:

28.

This diagram shows a:

a.	Dehydration synthesis reaction.
b.	hydrolysis reaction.
c.	Formation of a peptide bond.
d.	Both (a) and (c) above.
e.	None of the above.

29.

What molecule should be identified in place of (3).

a.	Inhibitor.
b.	Enzyme.
c.	Water.
d.	Inhibitors.
e.	None of the above.

30.

Which statement(s) are true?

a.	Enzymes facilitate reactions by lowering activation energy.
b.	Competitive inhibitors would bind the region labeled (2).
c.	This single enzyme is able to catalyze various reactions.
d.	Once an enzyme catalyzes a reaction, it is disabled.
e.	Both (a) and (b) above.

The two images below both show the structure of the cell membrane composed of two layers of phospholipids. Recall the chemical characteristics of a phospholipid and its role in the function of the membrane. The labels (numbers 1 through 5) for the two diagrams correspond to the same “part” of the two diagrams.

31.

Which of the labeled regions identifies a single phospholipid molecule?

a.	1
b.	2
c.	3
d.	4
e.	5

32.

Which region of the lipid bilayer is responsible for preventing polar molecules from freely passing through? Choose the answer that identifies the correct region along with the best explanation for this characteristic of the lipid bilayer.

a.	3. The nonpolar fatty acids chains prevent polar molecules from passing through.
b.	3. The polar phosphate heads interact with polar molecules, preventing them from passing through.
c.	3. The polar fatty acids chains interact with polar molecules, preventing them from passing through.
d.	4. The polar phosphate heads interact with polar molecules, preventing them from passing through.
e.	4. The polar fatty acids chains interact with polar molecules, preventing them from passing through.

The diagram below shows a transmembrane protein (a protein embedded in the lipid bilayer) that acts as a channel to transport molecules across the membrane. You should recognize the parts of the lipid bilayer by comparing them to an earlier question which shows the membrane in the same view.

The boxed area highlights details of the protein chain that sits in the membrane. Each “R” represents a separate sidechain and is labeled 1 through 5. Answer the following questions based on your understanding of the structure and characteristics of amino acids, proteins, and the lipid bilayer.

33.

This protein exhibits secondary structure characteristics called:

a.	backbones.
b.	hydrophilic.
c.	beta sheets.
d.	disulfide bonds.
e.	alpha helices.

34.

The sidechains labeled 4 and 5 can possibly belong to which of the following amino acids?

a.	Aspartic acid, glutamic acid, and valine.
b.	Alanine, glycine, and proline.
c.	Asparagine, glutamine, and threonine.
d.	Both (a) and (b) above.
e.	None of the above.

35.

Which of the following statements must be true about the amino acid sidechain labeled 1?

a.	This sidechain must have similar chemical characteristics to that of fatty acid chains.
b.	This sidechain must be able to interact with nonpolar molecules.
c.	This sidechain must be able to interact with water.
d.	Both (a) and (b) above can be true.
e.	Both (a) and (c) above can be true.