CB Test 1

36. Select the three key ideas of the cell theory. (many choice, select all that apply) - Cells are the basic units (of structure and function) of life - All living beings are made of cells. - All contemporary cells come from other cells - Cells can only do one job - Cells are able to spontaneously generate from inanimate matter

- Cells are the basic units (of structure and function) of life - All living beings are made of cells. - All contemporary cells come from other cells

40. Which of the following are some of the functions of proteins (many choice, select all that apply) - Gene regulation - Hormone receptors - Storage of genetic information - Most concentrated storage form of energy in cells due to their long fatty acid tails - Membrane transport - Enzymes

- Gene regulation - Hormone receptors - Membrane transport - Enzymes

8. What characteristics do all eukaryotic cells share? (Select all correct answers.) - Nucleus surrounded by its own membranes - Flagella - Cell wall - Other internal membrane bound organelles - Chloroplasts

- Nucleus surrounded by its own membranes - Other internal membrane bound organelles

16. Evidence for RNA World Hypothesis? (Many choice, select all that apply.) - Synthesis of deoxyribonucleotides from ribonucleotides - Basic metabolites like acetyl CoA having a ribonucleotide part - Peptidyl transferase activity of ribosomal RNA - The use of cellulose by the cell walls of plants, bacteria and fungi - Self-splicing introns in Tetrahymena

- Synthesis of deoxyribonucleotides from ribonucleotides - Basic metabolites like acetyl CoA having a ribonucleotide part - Peptidyl transferase activity of ribosomal RNA - Self-splicing introns in Tetrahymena

18. Indicate which of the following pairs of reactions with the given ΔG0' values may be coupled usefully so that the overall reactions could be exergonic? (Useful or Not useful) -12.5 kcal/mol and + 15.0 kcal/mol +12.5 kcal/mol and + 15.0 kcal/mol -8.5 kcal/mol and +5.0 kcal/mol +8.5 kcal/mol and -5.0 kcal/mol -7.3 kcal/mol and +2.0 kcal/mol

-12.5 kcal/mol and + 15.0 kcal/mol: not useful +12.5 kcal/mol and + 15.0 kcal/mol: not useful -8.5 kcal/mol and +5.0 kcal/mol: useful +8.5 kcal/mol and -5.0 kcal/mol: not useful -7.3 kcal/mol and +2.0 kcal/mol: useful

17. Arrange the following molecules from 1 to 5 where: most reduced (least oxidized) =1 least reduced (most oxidized)=5 - Carbon dioxide - Methane - Formaldelyde - Methanol - Formic acid

1. Methane 2. Methanol 3. Formaldelyde 4. Formic acid 5. Carbon dioxide

38. In simple carbohydrates, the hydrogen and oxygen typically occur in a ratio of: - 2:1 - 3:1 - 1:2 - 2:2

2:1

41. The oxidation of glucose to carbon dioxide releases how much energy? 1200 kcal/mol 686 kcal/mol 221 kcal/mol 935 kcal/mol 150 kcal/mol

686 kcal/mol

29. Cells lining the small intestine are specialized for absorbing nutrients from food. What type of structure might you expect these cells to have? - A thick cell wall to keep out the toxic molecules - A highly folded cell membrane to increase surface area - Lots of mitochondria - Multiple nuclei - Lots of ribosomes

A highly folded cell membrane to increase surface area

31. Mark whether each of these statements are True or false. A ∆G of zero means the system is at equilibrium. A positive ∆G tells us about the rate of a reaction. A negative ∆G is considered non-spontaneous/unfavorable. Enzymes increase the activation energy of reactions and thereby make reactions to occur faster. Enzymes alter the free energy change of a reaction. Enzymes can facilitate free energy coupling in cells between reactions.

A ∆G of zero means the system is at equilibrium. = True A positive ∆G tells us about the rate of a reaction. = False A negative ∆G is considered non-spontaneous/unfavorable. = False Enzymes increase the activation energy of reactions and thereby make reactions to occur faster. = False Enzymes alter the free energy change of a reaction. = False Enzymes can facilitate free energy coupling in cells between reactions. = True

20. What advantageous uses have viruses been shown to have? - They can be used as a means to introduce foreign genes into human cells, which may serve as a basis for treatment of human diseases by gene therapy. - The activities of viral genes mimic those of host genes so they are useful for studying mechanisms of DNA replication and gene expression in their much more complex hosts. - Insect-killing viruses may play an increasing role in the war against insect pests. - All are correct. - Bacteria-killing viruses may play an increasing role in the war against bacterial pathogens.

All are correct

5. Energy for metabolic purposes can be derived from which of the molecules in our diet: - Nucleic acids - Fats - All are possible - Carbohydrates - Proteins

All are possible

42. Why are cells so small? - As a cell gets bigger, its surface area increases much slower than its volume, reducing its ability to efficiently import nutrients and export wastes. - Very large cells would be unable to divide. - Because that's their place in the larger scheme of things in nature. - Because their components are microscopic. - As a cell gets bigger, its volume increases much slower than its surface area, spreading the cell's resources too thinly to confer any benefit.

As a cell gets bigger, its surface area increases much slower than its volume, reducing its ability to efficiently import nutrients and export wastes.

21. You are conducting an experiment by trying to reproduce the work performed in 1891 by Hans Driesch, a German embryologist. You are working with a fertilized sea urchin egg and allow it to complete the first cell division after fertilization. You then carefully separate the two cells of the embryo and allow their development to continue. Based on Driesch's experiment, which result below would you expect to happen? - Both of the cells will die. - One cell develops into half an embryo; the other develops into the other half of the embryo. - One cell develops into a defective embryo and the other dies. - One cell develops into a normal, though smaller, embryo; the other dies. - Both cells develop into complete and normal embryos that are somewhat smaller.

Both cells develop into complete and normal embryos that are somewhat smaller.

11. Why is butter solid at room temperature, whereas vegetable oil is liquid? - Butter is a polar molecule and vegetable oil is a nonpolar molecule - Butter is an unsaturated fat and vegetable oil is a saturated fat - Butter is a saturated fat and vegetable oil is an unsaturated fat - Butter is a nonpolar molecule and vegetable oil is a polar molecule

Butter is a saturated fat and vegetable oil is an unsaturated fat

50. Which of the following statements apply to bacteria but not to viruses. - Have genes that can be counted by the fingers on one hand - Can be infected by bacteriophages - Contain genetic material in the form of DNA or RNA - All apply

Can be infected by bacteriophages

24. Not a tenet of Cell theory? - Cells can arise only by division from a preexisting cell. - Cells divide only by fission. - The cell is the structural unit of life. - All organisms are composed of one or more cells.

Cells divide only by fission.

9. Which of the following is not considered a high energy compound? - CoA - ATP - NADPH - NADH - All are high energy compounds

CoA

27. Purines contain two rings. Pyrimidines contain one ring. The number of hydrogen bonds between certain base pairs is two or between certain base pairs is three. Use the above hints and your knowledge of what are purines and what are pyrimidines to answer the question pertaining to the figure below. The base-pairs in DNA shown below are between ______ and __________.

Cytosine (left), Guanine (right)

33. Which of the following is false about energy, its availability, and its sources? - All of the above are correct - All biological energy input for Earth comes from the Sun - Energy is captured by plants then transformed and transferred - Energy is lost as heat and radiated out into space - Energy can easily be created without the need for transference

Energy can easily be created without the need for transference

23. Virtually all chemical changes that take place in cells require ________, molecules that greatly increase the rate at which a chemical reaction occurs.

Enzyme

13. Apart from absence and presence of nucleus respectively another main feature distinguishes prokaryotic cells from eukaryotic cells. Select the best statement that represents this difference. - Eukaryotes are bacteria. All other living things are prokaryotes. - Eukaryotes have extensive membrane-bound organelles which divide the cell up into "rooms" which can specialize in different functions or contain different substances. - Eukaryotes are photosynthetic. Prokaryotes are not. - Eukaryotes do not have the elaborate internal structures of prokaryotes. - Eukaryotes have DNA, enzymes, and ribosomes, which prokaryotes do not.

Eukaryotes have extensive membrane-bound organelles which divide the cell up into "rooms" which can specialize in different functions or contain different substances.

12. Due to large amounts of ATP available in a cell for hydrolysis, the linear forms of glucose monomers in cells can directly undergo dehydration reactions with each other to form glycosidic linkages producing glycogen, without having to isomerize into the ring forms of glucose monomers. True or False

False

2. Anabolic pathways release energy via breaking down materials to form building blocks whereas catabolic pathways release energy by constructing macromolecules from building blocks. True or False

False

25. The four amino acid residues from the N to C direction, shown in the image below are Phe, Tyr, Asn, Lys. True or False

False

4. Both the first and the last reactions of glycolysis require the input of energy using ATP molecules as a major reactant. True or False

False

48. Within cells, the only known pathway that leads to Acetyl CoA formation, is the breakdown of carbohydrates such as glucose and therefore the cellular concentrations of this important metabolite is very low. True False

False

1. Which of the following amino acids has a net negative charge at physiologic pH (~7.4)? - Glutamic acid - Asparagine - Histidine - Lysine

Glutamic acid

46. Only one amino acid has two identical groups attached to its central carbon atom. Which of the following amino acids is it? - Cysteine - Valine - Alanine - Glycine

Glycine

19. Secondary structures such as alpha helix or beta-sheets are formed due to _______ bonding between the carbonyl and the amide functional groups of the _________ linkages along the ________ of the polypeptide. - Hydrogen; Peptide; R groups - Disulfide; Ester ; R groups - Peptide; Phosphodiester; Backbone - Peptide; Glycosidic; R groups - Hydrogen; Peptide; Backbone

Hydrogen; Peptide; Backbone

34. Which lipid would likely be a liquid at room temperature? - Oleic acid (an 18-carbon monounsaturated fatty acid) - Stearic acid (an 18‐carbon saturated fatty acid) - Palmitic acid (a 16-carbon saturated fatty acid) - Lauric acid (a 12-carbon saturated fatty acid)

Oleic acid (an 18-carbon monounsaturated fatty acid)

45. Which one of the following statements best describes the structure of a cell's plasma membrane? - Proteins embedded in two layers of phospholipid - A layer of protein coating a layer of phospholipids - Proteins sandwiched between two layers of phospholipids - Phospholipids sandwiched between two layers of proteins

Proteins embedded in two layers of phospholipid

15. Enzymes that break down DNA catalyze the hydrolysis of the covalent bonds that join nucleotides together. What would happen to DNA molecules treated with these enzymes? - No answer text provided. - The phosphodiester bonds between deoxyribose sugars would be broken. - The pyrimidines would be separated from the deoxyribose sugars - The two strands of the double helix would separate.

The phosphodiester bonds between deoxyribose sugars would be broken.

35. Match the relationship between the total free energies of reactants and products in a system at an instance and the value for ΔG at that instance, and the expected net direction of reaction at that particular instance. Total free energy of reactants is greater than total free energy of products present: Total free energy of reactants equal to total free energy of products present: Total free energy of reactants is smaller than total free energy of products present:

Total free energy of reactants is greater than total free energy of products present: ΔG>0, reaction tends to move toward products Total free energy of reactants equal to total free energy of products present: ΔG = 0, reaction is at equilibrium Total free energy of reactants is smaller than total free energy of products present: ΔG<0, reaction tends to move toward reactants

44. Non-competitive inhibitors result in ______ Km values but _____ Vmax values. - Increased; decreased - Unchanged; increased - Unchanged; unchanged - Decreased; increased - Unchanged; decreased

Unchanged; decreased

10. Kinetics of competitive inhibition in comparison with a control non-inhibited enzyme catalyzed reaction? - Vmax increases, Km is unchanged - Vmax stays the same, Km increases - Vmax stays the same, Km is unchanged - Vmax stays the same, Km decreases - Vmax decreases, Km is unchanged

Vmax stays the same, Km increases

22. For a given value of [S] in terms of Km, for an enzyme catalyzed reaction (each experiment has the same amount of enzyme), estimate the initial velocities of the reaction in terms of Vmax and match with the choices provided. Hint: use the Michaelis Menten equation given within the instructions of this exam. [S]=Km [S]= 2Km [S]= 3 Km [S]= (1/2) Km

[S]=Km -- V= (1/2) Vmax [S]= 2Km -- V= (2/3) Vmax [S]= 3 Km -- V= (3/4) Vmax [S]= (1/2) Km -- V= (1/3) Vmax

14. Which of the following best describes the composition of a nucleotide? - a carbon atom joined to hydrogen and three functional groups - four rings that are connected to one another - a five-carbon sugar attached to a phosphate group and nitrogenous base - two strands running in parallel orientation - a chain of carbon atoms with a carboxyl group bonded to one end - a pair of six-carbon rings attached to each other

a five-carbon sugar attached to a phosphate group and nitrogenous base

6. The molecule below:

an unsaturated fatty acid

30. Beta-lactam antibiotics such as penicillin acts as an irreversible inhibitor of a critical enzyme for cell wall synthesis from which organism and thereby killing it? - bacterium - viroid - virus - prion - fungus - mammalian cells

bacterium

26. Phospholipids have hydrophilic heads and hydrophobic tails. What does this indicate about the phospholipid structure? - phospholipids contain three fatty acids - the heads are polar and the tails are nonpolar - phospholipids are ionic in both regions - the heads are nonpolar and the tails are polar

the heads are polar and the tails are nonpolar

49. Doubling the concentration of enzyme will ______ the Vmax and _____ the KM. - halve, halve - not change, not alter - double, not alter - double, double - not alter, double

double, not alter

43. When an electron is transferred from one atom to another, that causes them to have opposing charges and leads to the formation of which type of bond? - ionic bond - nonpolar covalent bond - polar covalent bond - hydrophobic interactions - hydrogen bond

ionic bond

3. What are enantiomers? Choose the most accurate response. - molecules that have different molecular formulas but same structures. - groups of atoms covalently bonded to a carbon backbone that give properties different from a C-H bond. - substances with the same arrangement of covalent bonds, but the order in which the atoms are arranged in space is different. - molecules that are mirror images of each other and that cannot be superimposed on each other.

molecules that are mirror images of each other and that cannot be superimposed on each other

47. Your body extracts energy from the food you ingest by catalyzing reactions that essentially "burn" the food molecules in a stepwise fashion. What is another way to describe this process? - oxidation - dehydration - reduction - solvation

oxidation

37. You and your close friend have isolated a novel bacterium from the Sargasso Sea and cloned its pyruvate kinase gene. You want to test whether it can really catalyze the very last reaction of glycolysis which is a substrate phosphorylation reaction. You must provide which of the following substrates to test your idea, in addition to ADP and other components? - glucose 6-phosphate - lactate - ethanol - glyceraldehyde 3-phosphate - phosphoenol-pyruvate

phosphoenol-pyruvate

39. Entropy is associated with the _______ movement of particles of matter, which because they are _____ cannot accomplish a directed work process. - random, random - rapid, directed - random, slow - slow, rapid - rapid, random

random, random

28. A cell's reservoir of NADPH composes its __________. - backbone reservoir - structural stability - reducing power - oxidizing power

reducing power

32. Although there are a limited number of amino acids, many different types of proteins exist since the: - same amino acid can have many different properties - sequence and number of amino acids is different - size of a given amino acid can vary - chemical composition of a given amino acid can vary

sequence and number of amino acids is different

7. For the reaction B⟶A started at standard conditions with [B] = 1 M and [A] = 1 M in a test tube with the specific enzyme added to catalyze it. ΔG is initially a large negative number. As the reaction proceeds, [B] decreases and [A] increases until the system reaches equilibrium. How do the values of ΔG and ΔG°' change as the reaction moves toward equilibrium? - ΔG becomes positive and ΔG°' becomes positive - both ΔG and ΔG°' stay the same - ΔG stays the same and ΔG°' becomes less negative - ΔG becomes less negative and ΔG°' stays the same - ΔG reaches zero and ΔG°' becomes more negative

ΔG becomes less negative and ΔG°' stays the same