FIRST NINE WEEKS EXAM(TAKE HOME)

DUE by 12pm on SATURDAY October 18. Please send to garamir1@episd.org. Your name must be in the subject line. Any tests submitted (time stamped after 12pm on due date will not be scored).

ALL EXAMS MUST BE SUBMITTED IN THE FOLLOWING FORMAT FOR SCORING: NO EXCEPTIONS!!!!

1. IN A WORD DOCUMENT2. ONE PAGE only. SEE the LAST page of this file.

1. The figure shown depicts the molecular structure of a typical phospholipid bilayer. Which of the following statements regarding phospholipid bilayers is false?

A. Phospholipids have both hydrophobic and hydrophilic regions.B. In water, phospholipids tend to aggregate to form a bilayer.C. Individual phospholipids are free to change sides of the bilayer.D. The hydrophobic interior of the membrane is an oil-like fluid.E. The inner and outer halves of a bilayer often differ in phospholipid composition.

2. In the accompanying figure of an integral membrane protein, which of the following groups of terms correctly describes the three labeled regions (1, 2, 3) of the protein?

A. 1 = hydrophilic; 2 = hydrophobic; 3 = hydrophilicB. 1 = hydrophobic; 2 = hydrophobic; 3 = hydrophilicC. 1 = hydrophilic; 2 = hydrophobic; 3 = hydrophobicD. 1 = hydrophobic; 2 = hydrophilic; 3 = hydrophobicE. 1 = hydrophobic; 2 = hydrophilic; 3 = hydrophilic

3. Which of the following statements regarding cell–cell adhesion (shown) is false?

A. Proteins on the surfaces of cells are the main mediators of cell–cell adhesion.B. Oligosaccharides attached to proteins may be the basis for cell–cell adhesion.C. Oligosaccharides may be attached to membrane lipids.D. Cell–cell adhesion is important in animal development.

E. Different cells may have different glycoproteins on their surfaces

4. The surface area-to-volume ratio of an object can be decreased bya. cutting it into smaller pieces.b. flattening it.c. stretching it.d. making it spherical.e. All of the above

5. How does the surface area-to-volume ratio of a 1-mm cube compare to the surface area-to-volume ratio of a 3-mm cube?a. The 3-mm cube has a higher ratio.b. The ratio decreases as the cube becomes smaller.c. An increase in the volume doubles the ratio.d. The ratio decreases as the cube becomes larger.e. The ratio does not change.

6. The role of organelles is toa. provide structural support for the cell.b. decrease the flow of materials into and out of the cell.c. increase the efficiency of cellular activities.d. provide a means of cellular reproduction.e. regulate the flow of materials inside the cell.

7.What is the difference between “free” ribosomes and “attached” ribosomes?a. Free ribosomes are in the cytoplasm, whereas attached ribosomes are anchored to the endoplasmic reticulum.b. Free ribosomes produce proteins in the cytosol, whereas attached ribosomes produce proteins that are inserted into the ER.c. Free ribosomes produce proteins that are exported from the cell, whereas attached ribosomes make proteins for mitochondria and chloroplasts.d. Both a and be. Both a and c

8. The organelle shown below is found in all cells but is most numerous in cells requiring a large amount of energy (e.g., liver cells). What is the name of this organelle?

a. Lysosomeb. Golgi apparatusc. Rough endoplasmic reticulum

d. Mitochondrione. Chloroplast

9. Which of the following proteins powers the movement of both cilia and vesicles within a cell?a. Myosinb. Actinc. Keratind. Dyneine. Kinesin

10. Cilia and eukaryotic flagellaa. propel cells by rotation of the structures.b. contain microfilaments.c. contain microtubules that are sufficient to drive movement.d. must have a motor protein that uses the energy of ATP hydrolysis to power movement.e. contain centrioles.

11. The presence of _______ means that substances must pass through, rather than between, the epithelial cells that form the lining of the small intestine.a. gap junctionsb. tight junctionsc. desmosomesd. plasmodesmatae. Both a and b

12. You fill two containers with identical amounts of reactants A and B and enzymes 1–4. In the reactions shown below, if product D inhibits enzyme 2 and product F is an allosteric stimulator of enzyme 1, what will be the final result if you add extra product D to the second container? (Assume that both containers are given enough time for the reactions to go to completion.)

a. The concentration of product C will increase and there will be no change in the concentration of product F compared to that of the first container.b. The concentration of reactants A and B will increase relative to the first container.c. The concentration of product F will increase in the second container because more of D is converted back to C.d. The concentration of products E and F will both increase in the second container, since D inhibits enzyme 2.e. The concentration of product F will increase relative to the first container, since enzyme 2 will have been inhibited from converting C into D.

13. You are investigating a newly-discovered species. This organism lives in acidic pools in volcanic craters where temperatures often reach 100°C and normally stay above 90°C. You determine that it has a surface enzyme that catalyzes a reaction leading to its protective coating, and you decide to study this enzyme in the laboratory. At which temperature would you most likely find optimal activity of this enzyme?a. 0°Cb. 37°Cc. 55°Cd. 95°Ce. 105°C

14. In the pathway A + B C + D, enzyme X facilitates the reaction. If compound D inhibits enzyme X, you would conclude thata. enzyme X is an allosteric inhibitor of the reaction.b. compound D is an allosteric stimulator of the reaction.c. compound D is a competitive inhibitor of the reaction.d. enzyme X is subject to feedback stimulation.e. compound D is a coenzyme in the reaction.

15. Metabolism is organized into pathways that are linked in which of the following ways?a. All cellular functions feed into a central pathway.b. All steps in the pathway are catalyzed by the same enzyme.c. The product of one step in the pathway functions as the substrate in the next step.d. Products of the pathway accumulate and are secreted from the cell.e. Different substrates are acted on by the same enzyme.

16. Proteins consist of amino acids linked bya. noncovalent bonds.b. peptide bonds.c. phosphodiester bonds.d. van der Waals forces.e. Both a and b

17. The double-helix formation of DNA is caused bya. ionic bonds.b. covalent bonds.c. hydrogen bonds.d. hydrophobic side chains.e. None of the above

18. This figure shows the effect of pH on the activity of the enzymes pepsin, chymotrypsin, and arginase. Each enzyme has a different substrate. Consider a solution (solution 1) with equal concentrations of all three substrates for the three enzymes along with another solution (solution 2) containing all three enzymes. The fastest way to obtain a solution containing only pepsin substrate (removing the substrates for chymotrypsin and arginase) from solution 1 is to adjust the pH of solution 1 to _______ and add the enzyme solution (solution 2).

A. 2B. 5C. 7D. 8E. 10

19. Which statement about enzyme inhibitors and inhibition is true?

A. Noncompetitive inhibitors usually act by binding to the active site.B. Irreversible inhibition of enzyme activity is rare in cells.

C. A competitive inhibitor competes with the enzyme for substrate binding.D. An allosteric regulator affects enzyme activity using a mechanism similar to that seen in competitive inhibition.E. A competitive inhibitor usually binds covalently to the enzyme’s active site.20. Which of the following statements correctly explains why the reaction rate pattern shown in the graph for an enzyme–catalyzed reaction differs from the pattern without an enzyme?

A. With an enzyme, reaction rate initially increases rapidly due to increased substrate binding, but levels off once the enzyme is saturated.B. To obtain a curve as seen for the catalyzed reaction, the concentration of enzyme must be lower than substrate.C. The active site of an enzyme would be saturated with substrate at low substrate concentrations.D. The maximum rate of enzyme-catalyzed reactions is a measure of the enzyme’s catalytic efficiency.E. The rate of an uncatalyzed reaction is determined by the concentration of the substrate, but the rate of an enzyme-catalyzed reaction depends on the enzyme concentration.

21. Which of the following statements about the protein shown here is true?

A. Protein tertiary structure is primarily maintained by covalent bonds.B. This protein has a quaternary structure.C. The protein shown does not contain any -pleated sheets.D. The information necessary for correct protein folding is often present in a protein’s primary structure.E. Chemicals that disrupt hydrogen bonds and disulfide bridges leave proteins like ribonuclease permanently denatured.

22. Which of the following statements about the protein segment shown is true?

A. The structure shown is an example of tertiary structure.B. The structure shown is maintained by hydrogen bonding between amino acid side chains.C. Disulfide bridges and ionic interactions help maintain the structure shown.D. The type of structure shown always involves two polypeptides.E. A protein’s primary structure determines whether or not the structure shown will form.

23. Which of the five labeled bonds is formed by a condensation reaction between two amino acids?

A. 1B. 2C. 3D. 4E. 5

24. The diagram below shows three amino acids. Which of the following statements about these amino acids is true?

a. They have charged hydrophilic side chains.b. They have hydrophobic side chains.c. They have uncharged polar side chains.d. They form disulfide bridges.e. They are smaller than all other amino acids.

25. Consider the two labeled regions (1 and 2) of the phospholipid (phosphatidylcholine) shown here. Select the choice that makes the following statement true: Region 1 is _______ and would form the _______ of a cell membrane; region 2 is _______ and would form the _______ of a cell membrane.

A. hydrophobic; interior; hydrophilic; surfaceB. hydrophobic; surface; hydrophilic; interiorC. hydrophilic; surface; hydrophobic; surfaceD. hydrophilic; surface; hydrophobic; interiorE. hydrophilic; interior; hydrophobic; interior

26. Which of the following statements about polysaccharides or a polysaccharide is true?

A. Polysaccharides are polymers of monosaccharides connected by saccharide linkages.B. Glycogen is more branched than starch.C. Starches are polysaccharides of ribose.D. A starch molecule causes more osmotic pressure than would the unlinked monosaccharides that make it up.E. Cellulose is easily broken down because its linkages are not very stable.

27. Which statement about the reaction shown is true?

A. A hexose combines with a pentose to form a disaccharide.B. Two hexoses combine to form an oligosaccharide.C. This is a catabolic reaction.D. This is a condensation reaction.E. This is a hydrolysis reaction.

28. Macromolecules contain functional groups that affect the molecule’s chemical properties. Use your understanding of chemical bonds to determine which of the following functional groups could form hydrogen bonds with water.

A. The hydroxyl groupB. The aldehyde groupC. The carboxyl groupD. The phosphate groupE. All of the above

29. Which example shown (A–E) depicts the correct distribution of charge and hydrogen bonding between two water molecules?

A. Example AB. Example BC. Example CD. Example DE. Example E

30. In order to survive, cells musta. obtain and process energy.b. convert genetic information into proteins.c. replicate.d. Both a and be. All of the above

31. What is the major distinction between a prokaryotic and a eukaryotic cell?a. A prokaryotic cell does not have a nucleus, whereas a eukaryotic cell does.b. A prokaryotic cell does not have DNA, whereas a eukaryotic cell does.c. A prokaryotic cell is larger than a eukaryotic cell.d. Prokaryotic cells have not prospered, whereas eukaryotic cells are evolutionary “successes.”e. A prokaryotic cell cannot obtain energy from its environment.

32. Prokaryotic cells generally are smaller than eukaryotic cells becausea. prokaryotes have more diverse energy sources.b. prokaryotes have a capsule that limits cell growth.c. the rigid cell wall of prokaryotes limits cell size.d. prokaryotes lack the genetic material needed for protein synthesis.e. only eukaryotes have compartmentalization, which allows for specialization.

33. The role of organelles is toa. provide structural support for the cell.b. decrease the flow of materials into and out of the cell.c. increase the efficiency of cellular activities.d. provide a means of cellular reproduction.e. regulate the flow of materials inside the cell.

34. Which of the following is not a component of the endomembrane system?a. Rough endoplasmic reticulumb. Smooth endoplasmic reticulumc. Golgi apparatusd. Lysosomese. Plastids

35. Steroids such as cholesterol are synthesized bya. chloroplasts.b. lysosomes.c. the smooth ER.d. the Golgi apparatus.e. mitochondria.

36. Cells that perform little protein synthesis but are involved with the modification of molecules that enter the body through the digestive system typically have large amounts ofa. RER.b. mitochondria.c. ribosomes.d. smooth ER.e. lysosomes.Answer: dTextbook Reference: Concept 4.3 Eukaryotic Cells Have a Nucleus and Other Membrane-Bound Compartments

37. Lysosomes are important to eukaryotic cells because they contain

a. photosynthetic pigments.b. starch molecules for energy storage.c. their own DNA molecules.d. the cells’ waste materials.e. digestive enzymes.Answer: e

38. The folds of the inner mitochondrial membranea. increase the volume of the mitochondrial matrix.b. create a large membrane surface for reactions within the mitochondrion.c. increase the number of ribosomes within the membrane.d. anchor the mitochondrial DNA.e. have no known purpose.

39. In the mitochondria, the energy from “food” molecules (such as glucose) that are partially broken down in the cytosol are converted toa. ATP.b. CTP.c. GTP.d. TTP.e. UTP.

40. How would the surface area-to-volume ratio of eight 1-mm cubes compare to the surface area-to-volume ratio of one 2-mm cube? (See diagram shown.)

A. They would be equal.

B. The 2-mm cube would have a greater surface area-to-volume ratio.

C. The 1-mm cubes would have a greater surface area-to-volume ratio.

D. The 2-mm cube would have a greater surface area; the 1-mm cubes would have a greater volume.

E. Cannot determine with the information provided.

41. Which of the following correctly lists the order in which this newly synthesized membrane moves through the endomembrane system?

A. Rough ER, smooth ER, Golgi, plasma membrane

B. Smooth ER, rough ER, Golgi, plasma membrane

C. Golgi, smooth ER, rough ER, plasma membrane

D. Plasma membrane, smooth ER, rough ER, Golgi

E. Golgi, rough ER, smooth ER, plasma membrane

42. Use your knowledge of eukaryotic cell components and their functions to identify the genetic disease described here that is most likely to affect lysosomes.

A. Congenital disorders of glycosylation (CDGs) Type II—includes defects in genes that code for enzymes that make the carbohydrate part of glycoproteins.

Symptoms vary depending on the specific enzyme affected.

B. Cystic fibrosis—a genetic disease caused by a mutation in a gene for an ion channel protein that is important in making cell secretions like sweat and mucus.

C. Acatalasia—a disorder in which no catalase is made. This enzyme catalyzes reactions that produce hydrogen peroxide. Acatalasia symptoms include increased periodontal infections.

D. Gaucher’s disease—a defective gene prevents formation of an enzyme important in the recycling of worn-out cells. In the absence of this enzyme, the lipid glucocerebroside accumulates, causing enlargement of the spleen, liver, and bone marrow.

E. Leber’s hereditary optical neuropathy (LHON)—a genetic disease caused by defects in genes that code for polypeptides in a membrane-embedded protein complex important in energy metabolism. Symptoms include loss of central vision.

43. Which of the following is a function of animal tight junctions (shown)?

A. Facilitating communication between cells

B. Forcing substances to pass through epithelial cell membranes rather than intercellular spaces

C. Providing a mechanism for transmission of electric signals between cells

D. Providing mechanical stability via a direct link to cytoskeleton filaments

E. Allowing passage of dissolved molecules between cells

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