Bil 150 June 1, 2005

Summer 2005 Test 1.

Part 1. Multiple Choice: Directions: Pick the BEST answer from those given. 01. Suppose that you had 5 bacterial cells, which of the following would you pick as the most likely structure that these cells would fit inside? a) a carbon atom b) a eukaryotic cell c) a viral particle d) a hydrogen bond e) none of these is correct 02. Which of the following substances is characteristic of ”all” phospholipid molecules, but is not found in ordinary triglycerides? a) inorganic phosphate b) fatty acids c) glycerol d) ester bonds e) choose this answer if all of these are characteristics 03. In general, of all the molecules found in living cells, by far the most abundant is (are)? a) protein b) various ions c) water d) nucleic acid e) none of above 04. Suppose that the pH within a mitochondrion is 7.25 and the pH within a plant cell vacuole is 6.25. Choose the ”correct” statement regarding this situation. a) vacuole is more basic b) mitochondria is more acidic than vacuole c) vacuole contains a greater number of OH ions than mitochondria d) the concentration of H+ is greater in the vacuole e) none of the above is correct 05. "Peptide bond" is to "amino acid" as ” _________” is to "monosaccharide". a) glycosidic bond b) phosphodiester bond c) hydrogen bond d) all of these e) none of these 06. Which of the following molecules would be classed as the most structurally unique in the sense of being species specificity? a) glycogen b) testosterone c) glycine d) phospholipid e) catalase 07. Which of the following statements is ”not” true of cells: a) all cells are surrounded by a membrane b) cells can arise spontaneously without pre-existing cells c) all known living systems are composed of cells d) cells operate by same general laws as non-living systems e) choose this answer if all of the are true ststements 08. Choose the one mostlikely to be a "glycosidic bond": a) H-N-C=O b) –S-Sc) C-O-C d) N-H2

e) –O-H

09. Which of the following is the strongest molecular force involved within tertiary structure in globular proteins? a) hydrophobic interactions b) alpha helix formation c) hydrogen bonds d) disulfide bridges e) none of these 10. Which of these is present in both metazoan or metaphytian cells and also present in prokaryotic cells? a) chloroplasts b) lysosomes c) cellulosic cell walls d) ribosomes e) none of these

Bil 150 ss 2005 – Test 1 – page 2

11. Protein X has 3 amino-ends and 3 carboxyl-ends with a total of 300 amino acids residues. Which of the following might you conclude with certainty about protein X ? a) it has a total of 299 peptide bonds b) it has quarternary structure c) it is composed of 3 equal length polypeptide chains d) the entire protein shows alpha helical structure e) none of the above is correct 12. Hydrogen bonds? a) can form between any chemical group having a hydrogen atom b) contain about the same energy (strength) as covalent bonds c) are required for the secondary level of protein structure d) must involve amine groups e) none of the above 13. Which of the following is incorrect? a) triglycerides are common storage forms of fat b) formation of a glycosidic bond releases H2O c) the CH3 group of fatty acids is bound to glycerol d) complete hydrolysis of glycogen yields only glucose e) choose this answer if all of these are correct 14. Which of the following is not correct concerning a plot of the rate of an enzyme reaction against substrate concentration? a) such a graphic plot shows saturation b) the plot reveals that the Ea is greater for enzyme reactions c) it reveals a maximum velocity for enzyme reactions d) choose this answer if all of these are correct statements 15. Which of these is not true of classical enzymes? a) all are proteins b) all show substrate specificity c) function by increasing reaction rate d) alter the thermodynamics of a reaction e) choose this if all of the above are true of enzymes 16. If a sample of homogenate containing peroxidase produced 318 umoles of O2 in 12 min at 37oC, then the reaction rate for this sample of peroxidase is? a) 15.6 gm/min b) 244.6 umoles/min c) 26.5 umoles/min d) 413.4 gm/umole e) undeterminable from this data 17. The smallest portion of an atom, the part which has the littlest mass of an atom, is? a) molecule b) electron c) proton d) neutron e) none of these is correct 18. Which of the following is a specific example of a true biological polymeric molecule ? a) protein b) lipid c) monosaccharide d) NutraSweet e) none of these

Bil 150 ss 2005 – Test 1 – page 3

19. Covalent bonds? a) form only between non-identical atoms b) involve the complete transfer of electrons from one atom to another c) involve the sharing of electrons between atoms d) a & c only are correct e) none of the above is correct 20. Which of the following properties of water is properly matched with its correct definition? a) adhesion - the tendency of unlike molecules to repel each other b) cohesion - tendency of water molecules to hydrogen bond and attract each together c) capillary action - the tendency of water to vaporize d) surface tension - the hydrogen bonding of water in ice e) choose this answer if not of these is correct 21. A buffer is a substance that resists changes in pH.

a) true

b) false

22. A scientist hypothesizes that drug X will prevent hair loss. She designs an experiment giving mice in group 1 a normal diet without drug X and mice in group 2 a normal diet with drug X. Which group is the control group? a) group 1 b) group 2 c) there is no control group 23. A hypothesis which, over a long time becomes supported by a large body of observations and experimental evidence, may often be referred to by scientists as a? a) placebo b) law c) theory d) hypothesis e) none of these 24. Which of these is (are) major unifying concept(s) of biology? a) that cells use the same laws of bioenergetics to function as the laws of the physical universe b) the theory of evolution c) the Cell Theory d) all of these are unifying concepts 25. The theory that life may have arisen by the seeding of Earth via meteorite bombardment is often known by the name? a) Special Creation b) Evolution c) Panspermia d) none of these 26. Under the current theories of chemical evolution, which came first protobionts or amino acid monomers? a) amino acids came first b) protobionts came first c) neither is correct 27. A most likely source for the origins of the pre-biotic chemicals of living systems was? a) meteorites or comets b) hydrothermal vents c) abiotic chemical synthesis (ala Miller) d) choose this answer if any of these may have been likely to have been an origin 28. There are very unique and special laws of chemistry and physics, which are applicable only to living cells, and no other forms of matter? a) true b) false 29. Biology 150 is required of all college students receiving a baccalaureate degree. You are a college student, therefore you must take Biology 150. This is an example of what type of scientific reasoning ? a) deductive reasoning b) a theory c) a hypothesis d) inductive reasoning e) none of these

Bil 150 ss 2005 – Test 1 – page 4

30. Which of the following statements about cells is (are) correct ? a) all cells contain membranes b) all living things are composed of cells c) all cells arise from pre-existing cells d) choose this answer if all of the above are correct 31. Which of the following sequences is in the most likely correct order of increasing complexity? a) cell --> tissue --> organ --> organ system b) macromolecule --> atom --> cell --> organelle c) population --> ecosystem --> organism --> community d) cell --> chemical --> organism -- > tissue e) choose this answer if none of these is a correct sequence 32. A molecule is a group of atoms held together by energy in the form? a) chemical bonds b) electrostatic repulsion c) enzymes d) none of these is correct 33. The chemical formula which lists only the elemental composition of a molecule is called its? a) empirical (molecular) formula b) structural formula c) monosaccharide formula d) branched formula e) choose this answer if none of these is correct 34. The hydrophobic portion of a triglyceride is which end this fat/lipid? a) fatty acid end b) glycerol end c) phosphate end d) none of these is correct 35. A functional group [OH] can make a molecule containing it an alcohol. The group OH is called? a) a hydroxyl group b) a carboxyl group c) a methyl group d) a sulfhydryl group e) choose this answer if none of these is correct 36. From the list of proteins given below, pick the one that is most likely a complex protein? a) albumins b) globulins c) histones d) nucleoproteins e) none of the above is correct 37. Enzymes which possess different amino acids sequences, but have the same catalytic function, especially when compared between different species are? a) polymorphic b) invariant c) site specific d) only simple proteins e) none of these 38. The portion of the structure of an enzyme where a inhibitor or regulator molecule binds is called? a) product site b) active site c) allosteric site d) levorotatory site e) none of these 39. Current predictions of the ‘Carrying Capacity’ of Earth have human populations reaching a maxima of about? a) 1 million b) 1 billion c) 10 billion d) 100 billion e) none of these 40. Which of the following is a “greenhouse gas” ? a) oxygen b) nitrogen d) argon e) choose this answer if all of the above are correct

c) methane

Bil 150 ss 2005 – Test 1 Essay – page 1

Part 2. Short answer/essay. 1. GIVEN: A series of enzymes catalyzing this reaction: A ---w---> B ---x---> C ---y---> D ---z---> E a. What is substance A _substrate (reactant)__? What is E ___product___________? and What is x ? ___an enzyme______________? (3 pts) b. Using this pathway as a model, describe how feedback inhibition would work (3 pts)? product E would go back and ‘bind’ to enzyme w, an initial enzyme, altering its activity and reducing the rate of conversion of substrate A toward product E. and how allosteric modulation would work? (3pts) allosteric modulation works by having a regulator molecule (enhancer or inhibitor) binding to an allosteric site (non active site region) and altering the shape of the enzyme, thereby reducing or enhancing its ability to bind its substrate.

2. During the running of a marathon a distance runner's body temperature can rise up to 105oC and blood plasma volume can decrease by 10% to 15%. By continuous sweating a runner can dissipate some of this heat. What is the physical property of water that allows heat dissipation and by sweating off 500 cubic centimeters of water, how many calories of heat energy can this runner dissipate. (Reminder: density of water 1 cc = 1 gm). (6 points)

Heat of vaporization – releases 540 cal per cc (gm) of water, thus 500 ml (cc) of water would release 500 x 540 = 270,000 calories of heat or 270 Calories (kilocalories)

3. This diagram is a portion of a polypeptide chain. (10pts) 3a. IDENTIFY the type of molecular interaction (forces) at each of the specific labels. A. ___hydrophobic interactions__________ B. ___hydrogen bonds____________________ C. ___disulfide bond (bridges)__________ D. ___ionic bond________________________ 3b. At what level of protein structure are the above forces commonly functional ? E. ___teritary level ___________________

Bil 150 ss 2005 – Test 1 – page 2

4. In the figures to the left we see plots of the rate of enzyme reaction vs. temperature and pH. (9 points) a.

Which curve (#1 to #5) was generated using an enzyme which likely from a bacterium that lives in hot springs at temps above 70oC ____3______?

b.

The temperature optima for enzyme 1 is _____37 C___?

c.

Which curve was most likely generated from an enzyme of the human stomach where conditions are highly acid? _______4_________?

5. Answer each question about the functional groups depicted in the figure below (8pt). a. Which molecules holds a sulfhydryl __B___? b. Which molecule contains a hydroxyl group ___E_____? c. Which holds an aldehyde ___C______? d. A phosphate is seen in which molecule ______D__________?

7. Use figure 1, which is a plot of rate of hexokinase vs. its substrate concentration under 2 different conditions (diamonds is the rate without an inhibitor and squares with an inhibitor) to answer these questions. (8 points - remember the units)

Fig 1. - Hexokinase umol glucose-6-P per min

25 20 15 10

A. What is the Vmax of the native (without inhibitor) reaction? __20 umol glu-6-P_?

5 0 0.5

1

1.5

2

4

8

16

umol glucose

32 40 60 80

B. What is the Km of the inhibited enzyme reaction? ____1 umol glucose________? C. What kind (type) of enzyme inhibition is being shown by this enzyme __non-competitive_?