MCB 181 005/6 Exam 2 KEY Lyons/Beilstein150 pts. Questions are equally weighted

1. Which of the following statements represents a major difference between prokaryotic cells and eukaryotic cells?

A. Eukaryotes have cells while prokaryotes do not.B. Eukaryotes are generally larger in size than prokaryotes.C. Eukaryotic cells tend to have much more extensive inner membrane systems and larger

numbers of intracellular organelles than do prokaryotes.D. Prokaryotes are not able to carry out aerobic respiration, a process that requires a

complex inner-membrane system.E. both B and C

(E) Definition.

2. The small intestine is the site of digestion and absorption of nutrients. A single layer of epithelial cells lines the small intestine. In the duodenum (the first section of the small intestine), these epithelial cells secrete large quantities of digestive enzymes into the digestive tract. Which of the following features would you expect to find in these epithelial cells?

A. They would have an expanded nucleolus.B. They would contain large quantities of rough endoplasmic reticulum.C. They would have larger nuclei than cells that secrete large quantities of lipids.D. They would contain large numbers of lysosomes.E. They would have more smooth endoplasmic reticulum than rough endoplasmic

reticulum.(B) Site of protein synthesis.

3. You have a distant cousin, age 5, who is always tired and fatigued and is not able to play games and sports like other healthy children. He most likely has an enzyme deficiency or defect associated with which intracellular organelle?

A. Golgi apparatusB. mitochondriaC. ribosomesD. lysosomesE. smooth endoplasmic reticulum

(B) Mitochondria is site of ATP synthesis, ATP is energy currency of the cell.

4. Amoebae move by crawling over a surface (cell crawling). Which one of the following processes is part of this type of movement?

A. reinforcing the pseudopod with intermediate filamentsB. setting up microtubule extensions that vesicles can follow in the movement of cytoplasmC. growth of actin filaments to form bulges in the plasma membraneD. cytoplasmic streamingE. Both B and C

(C) Cell crawling is due to actin and myosin.

5. Researchers tried to explain how vesicular transport occurs in cells by attempting to assemble the transport components. They set up microtubular tracks along which vesicles could be transported, and they added vesicles and ATP (because they knew the transport process requires energy). Yet, when they put everything together, there was no movement or transport of vesicles. What was missing?

A. mitochondriaB. an axonC. myosin D. contractile microfilamentsE. motor proteins

(E) Microtubules use motor proteins such as dynein.

6. Viruses use the host's machinery to make copies of themselves. However, some human viruses, like dengue, require a type of replication that humans do not normally do. For example, humans normally do not have the ability to convert RNA into DNA. How can these types of viruses infect humans, when human cells cannot perform a particular role that the virus requires?

A. Viruses can stay in a quiescent state until the host cell evolves this ability.B. The virus infects only those cells and species that can perform all the replication roles

necessary.C. The virus has in its own genome the code for any specialized enzymes that the host

does not have.D. The virus causes mutations in the human cells, resulting in the formation of new

enzymes that are capable of performing these roles.E. The virus actually infects bacteria living inside the human body.

(C) Viral genome encodes proteins for reverse transcription.

7. Which of the following best illustrates the order of events that occurs during a viral infection?

A. (1) entry; (2) replication of viral genome; (3) transcription; (4) production of viral proteins; (5) assembly of new virions

B. (1) entry; (2) production of viral proteins; (3) replication of viral genome; (4) transcription; (5) assembly of new virions

C. (1) entry; (2) transcription; (3) production of viral proteins; (4) replication of viral genome; (5) assembly of new virions

D. (1) entry; (2) production of viral proteins; (3) transcription; (4) replication of viral genome; (5) assembly of new virions

E. none of the above accurately illustrates the order of events during viral infection(C)

8. Which statement best explains why the existence of multiple steps in a signal transduction pathway allows it to be regulated by several other pathways?

A. Multiple steps allow the signal to be amplified.B. Multiple steps provide a series of points where hormone can bind.C. Multiple steps convert the signal from one form to another.D. Multiple steps provide a series of points where cross-talk can occur.E. Multiple steps increases the number of targets in the nucleus.

(D) Cross talk occurs when signaling pathways interact. The more steps in the pathway, the more opportunity for cross-talk.

9. The most abundant protein found in the extracellular matrix of animal cells is _____.A. collagenB. pectinC. celluloseD. hemoglobinE. integrin

(A) ECM definition

10. Which of the following statements most accurately describes the function of plasmodesmata in plant cells or gap junctions in animal cells?

A. Gap junctions allow passage of proteins and small molecules between adjacent cells.B. Plasmodesmata allow passage of proteins and small molecules between adjacent cells.C. Plasmodesmata allow passage of only proteins between adjacent cells.D. Gap junctions allow passage of only proteins between adjacent cells.E. Both gap junctions and plasmodesmata allow passage of proteins and small molecules between

adjacent cells.(B) Plasmodesmata allow proteins to pass, gap junctions do not.

11. Put the steps of the process of signal transduction in the order they occur:1. A conformational change in the signal-receptor complex activates an enzyme.2. Protein kinases are activated.3. A signal molecule binds to a receptor.4. Target proteins are phosphorylated.5. Second messenger molecules are released.

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

(A) or (B)

12. A G-protein receptor with GTP bound to it _____.A. signals a protein to maintain its shape and conformationB. directly affects gene expressionC. will use cGMP as a second messengerD. is in its active stateE. is in an inactive state

(D)

13. Blood sugar is regulated by two pancreatic hormones, insulin and glucagon. When blood sugar rises, insulin is released; it binds to receptors and, through signal transduction, results in an increase in glucose uptake by cells, which effectively lowers blood glucose levels. When blood sugar decreases, glucagon is released, binds to cell receptors, and causes glucose to be released into circulation, thereby increasing blood glucose levels. Diabetes mellitus is a disorder that results from excessively high levels of blood glucose. Type II diabetics have normal to elevated levels of insulin. What, then, might be causing their elevated blood glucose levels?

A. defective receptorsB. defective second messengerC. overproduction of glucagonD. inadequate insulin productionE. none of the above reasons explain what might be causing elevated blood glucose levels

(A) Defective receptors are unable to receive the signal from insulin, which would result in glucose uptake by cells, thereby reducing blood glucose levels.

14. Which of the following statements is (are) inconsistent with the first and second laws of thermodynamics?

A. Living organisms can produce energy. B. Chemical energy may be converted to light energy. C. The total energy of a system is available to do work. D. Potential energy may be used to do work. E. Both a and c

(E) 15. Which of the following statements concerning energy transformations is true?

A. Increases in entropy reduce usable energy. B. Energy may be created during transformation. C. Potential energy increases with each transformation. D. Increases in temperature decrease total amount of energy available. E. Decreases in entropy reduce usable energy

(A)

16. When NAD+ is converted to NADH it is _____; When FADH2 is converted to FAD it is ____. Of these four molecules, _____ stores the most energy for use in oxidative phosphorylation.

A. Reduced; Oxidized; FADH2

B. Oxidized; Reduced; NADHC. Reduced; Oxidized; NADHD. Oxidized; Reduced; FADH2E. None of the above

(C)

The following three questions refer to the above diagram which depicts a metabolic pathway with substrates, intermediates and products indicated with letters A-I, and the enzymes mediating the reactions indicated with numbers 1-8. 17. If enzyme 2 is inactive, which of the following products would be produced from the metabolic pathway?

A. A and B B. C and G C. C and D D. E and F E. None of the above

(A) or (E)

18. Negative feedback regulation of synthesis of product I most likely involves _______ through _______ by product I.

A. reduction in levels of intermediate D; inhibition of enzyme 3 B. reduction in levels of intermediate C; inhibition of enzyme 2 C. reduction in levels of intermediate G; inhibition of enzyme 6 D. increase in levels of intermediate D; activation of enzyme 3 E. None of the above

(C)

19. Products I and F have to be kept at equal molar proportions in the cell. If there is an increase in levels of product I, a positive feedback regulation of synthesis of product F would most likely occur through

A. inhibition of enzyme 3 by product F. B. activation of enzyme 3 by product F. C. inhibition of enzyme 6 by product I. D. activation of enzyme 5 by product I. E. activation of enzyme 2 by product I.

(D)

20. In aerobic cells, ____ in usually the immediate source of energy, used in an _____ reaction, and primarily generated in _____.

A. glucose; exergonic; chloroplastsB. ATP; endergonic; mitochondriaC. Acetyl-CoA; exergonic; cytoplasmD. pyruvate; endergonic; mitochondriaE. None of the above

(E)

21. If you are treated with a drug that causes the inner mitochondrial membrane to become permeable to small ions, what will happen and why?

A. You will require more oxygen because more pyruvate is producedB. You will get hot because more entropy occurs during oxidative phosphorylationC. You will die because you cannot generate enough Acetyl CoAD. Your muscles will get sore because of the buildup of lactic acidE. None of the above

(E). You will die because you cannot generate enough ATP. Mitochondria require a hydrogen gradient between their innermembrane and matrix in order to generate ATP using ATP synthase.

22. What are the reactants and products during the conversion of the 3 carbon molecule produced by glycolysis to the 2 carbon molecule required by the TCA cycle?

A. Reactants: Acetyl CoA, NAD+, ADP, , Pi, FAD, H2O; Products: CO2, NADH, FADH2, ATPB. Reactants: Glucose, ADP, NAD+, Pi; Products: Pyruvate, H2O, ATP, NADHC. Reactants: Pyruvate, NAD+, Coenzyme-A; Products: NADH, CO2, Acetyl CoA D. Reactants: Glucose, ADP, Pi; Products: ATP, Ethanol, CO2E. None of the above

(C)

23. Two ATP molecules are expended in the energy investment phase of glycolysis. Why is this energy needed to begin the process of glucose catabolism?

A. It is needed because glycolysis is considered an exergonic process which always requires input of energy from ATP.

B. It is needed to generate the electron carrier NAD+.C. It is needed to induce the enzymes of glycolysis.D. Some energy must be invested to make the glucose molecule unstable and begin the

process of catabolism.E. None of the above.

(D)

24. If the above picture represents aerobic cellular metabolism, what are the items labeled A, B, C, D?

A. CO2, H2O, glucose, Calvin cycleB. glucose, lactate, ethanol, Krebs cycleC. pyruvate, acetyl-CoA, oxaloacetate, TCA cycleD. glucose, pyruvate, acetyl-CoA, the citric acid cycle E. None of the above

(D)

25. Humans extract about 18 times as much energy from glucose as do yeast. Which of the following best explains why?

A. Oxidative phosphorylationB. PhotophosphorylationC. Substrate-level phosphorylationD. All of the aboveE. None of the above

(A)

26. When used by the electron transport chain, which molecule ultimately generates more energy, NADH or FADH2. Why?

A. NADH; The H+ gradient made from electron transport using NADH is located in a different part of the mitochondrion than the H+ gradient made using FADH2.

B. FADH2; It takes more energy to make ATP from ADP and Pi using NADH than using FADH2.

C. NADH; FADH2 is made only in the citric acid cycle while NADH is made in glycolysis, acetyl CoA formation, and the citric acid cycle.

D. FADH2; Fewer protons are pumped across the inner mitochondrial membrane when NADH is the electron donor than when FADH2 is the electron donor.

E. None of the above(E)

27. During photosynthesis, the light energy from the Sun is captured and stored in the bonds of _____.

A. oxygenB. waterC. glucoseD. hemoglobinE. NADH

(C)

28. Based on what you know about the structure and function of the antenna complex, irradiating a leaf with which of the following light types would result in the release of the greatest quantities of oxygen?

A. red and orange lightB. green and blue lightC. violet and red lightD. red and green lightE. red and blue light

(E)

29. Most of the enzymes of the Calvin cycle also function in other metabolic pathways. This should not be a surprising finding, because _____.

A. metabolic reactions are catalyzed by enzymes B. there is a close relationship between carbohydrate synthesis and carbohydrate

metabolismC. the Calvin cycle probably evolved at the same time as did glycolysisD. the Calvin cycle is nearly ubiquitous in cells, as are metabolic pathwaysE. metabolic processes require ATP and a molecule that can be reduced

(B)

30. In the carbon fixation step of the Calvin cycle, ribulose-1,5-bisphosphate (a five-carbon compound) is carboxylated to produce _____.

A. acetyl CoA (two carbons) and oxaloacetate (four carbons)B. glucoseC. 2 three-carbon compoundsD. 5 molecules of carbon dioxideE. 2 pyruvate molecules

(C) 6 carbon molecule is immediately broken down into two three carbon molecules

31. What is the difference between a chromatid and a chromosome?A. Chromatids consist of DNA, whereas chromosomes consist of proteins.B. Chromosomes are always replicated, whereas chromatids are not.C. A chromatid always consists of two linear DNA molecules, whereas a chromosome

always consists of just one linear DNA molecule.D. A chromatid is one half of a replicated chromosome, whereas a chromosome consists of

DNA wrapped around proteins in a highly organized manner.E. None of the above

(D) Definition

32. What is the final result of the mitosis of a 1n somatic cell?A. genetically identical 2n gamete cellsB. genetically different 2n somatic cellsC. genetically identical 1n somatic cellsD. genetically identical 2n somatic cellsE. genetically identical 1n gamete cells

(C)

33. Homologous chromosomes _____.A. carry the same allelesB. are found only in haploid cellsC. carry the same genesD. are identicalE. both A and D

(C)

34. For the male lubber grasshopper shown in the figure what are the (1) haploid number, (2) ploidy, and (3) total number of chromosomes?

A. (1) 12; (2) 2n; (3) 12B. (1) 12; (2) n; (3) 23C. (1) 23; (2) 2n; (3) 23D. (1) 12; (2) 2n; (3) 23E. (1) 12; (2) n; (3) 24

(D)

35. The diploid chromosome number of a roundworm species is 6. You have a male and a female roundworm that are planning a family. Assuming there is no crossover, and random segregation of homologues during meiosis, how many different possible combinations of chromosomes might there be in the offspring?

A. 2B. 4C. 8D. 16E. 64

(E) 2 X 2 X 2 = 8 total possible gametes in 1 parent. 8 X 8 = 64 possible combinations in offspring.

36. The variation among offspring, and the fact that they are genetically different from their parents, is not due to which of the following?

A. random alignment of homologues during prophase IB. crossing overC. random alignment of sister chromatids in metaphase IID. fertilizationE. both A and D

(A) random alignment of homologues occurs in metaphase I

37. In the figure, what major event is taking place during this phase of meiosis?A. anaphase IB. homologues separateC. separation of sister chromatidsD. both A and BE. both A and C

(D)

38. Adaptation to a changing environment occurs most efficiently through which of the following processes?

A. sexual reproduction in a selfing organismB. asexual reproduction and genetic recombinationC. sexual reproduction in an outcrossing organismD. mutationE. both A and D

(C)

39. Nondisjunction in meiosis produces _____.A. zygotesB. aneuploidsC. trisomy 21D. diploidsE. both B and C

(E)

40. Which of the following would enable you to detect aneuploidy?A. autosomyB. karyotypingC. synapsisD. syngamyE. none of these allow the detection of aneuploidy

(B)

41. An advantage of sexual reproduction is hypothesized to be _____.A. reducing genetic diversityB. increasing the chance that a parent will transmit all their genes to an offspringC. avoiding the transmission of harmful alleles to offspringD. the production of clonesE. both B and C

(C)

42. Which statement is FALSE concerning gametes produced by meiosis?A. Gametes contain nonrandom combinations of maternal and paternal chromosomes.B. Gametes contain a random assortment of maternal and paternal alleles.C. Gametes contain half as many chromosomes as the parent cell.D. Gametes contain a random assortment of maternal and paternal chromosomes.E. all of the statements are true

(A)

43. Flagella are found in both eukaryotic cells and prokaryotic cells. Despite the functional similarities of all flagella, scientists suspect that eukaryotic and prokaryotic flagella have evolved independently. Why don't they think there is a common evolutionary origin for prokaryotic and eukaryotic flagella?

A. Prokaryotic flagella do not protrude outside the cell wall, whereas eukaryotic flagella are membrane-bound extensions of cytoplasm.

B. Prokaryotic flagella do not require energy in the form of ATP as eukaryotic flagella do.C. Prokaryotic flagella are an adaptation to scarce nutrient supplies, whereas eukaryotic

flagella are designed to protect.D. Prokaryotic flagella undergo an undulating motion and are covered by a plasma membrane;

eukaryotic flagella move by rotating and lack a plasma membrane.E. None of the above.

(E)

As a hamster geneticist, you have identified two characters of interest, nose color and tail color, each of which has two traits, white and black. In mice, a dihybrid cross yields a ratio of phenotypes of: 9: black nose; black tail 3: black nose; white tail 3: white nose; black tail 1: white nose; white tailHowever, in your hamsters, you observe a ratio of phenotypes of: 1: black nose; black tail 99: black nose; white tail 99: white nose; black tail 1: white nose; white tail.

Using these data, answer the following questions:

44. What best explains these data?A. Mendel’s first and second laws of geneticsB. The genes in mice are on the same chromosome; the genes in hamsters are on different

chromosomesC. The genes in mice are on different chromosomes; the genes in hamsters are on the

same chromosomeD. A and CE. None of the above

(C)

45. If T/t is used for the tail character and N/n is used for the nose character, what are the genotypes of your parental hamsters and, following strict Mendelian genetics, the expected gametes they would produce?

A. NnTt, NnTt; Tn, NtB. NnTt, NnTt; TT, Tn, Nt, ttC. N_T_, NnTt; TT, Tn, Nt, tt D. N_T_, N_T_; TT, Tn, Nt, tt E. None of the above

(E) Parent genotypes are: NnT,; nntt. Gametes are Nt, nT, nt

46. How far away from one another are the hamster genes controlling nose and tail color?A. 0.1 cMB. 1cMC. 10cMD. On different chromosomesE. None of the above

(B)

This human pedigree tracks a disease occurrence through three generations. Please use this pedigree to answer the following two questions:

47. In this human pedigree for a disease, what kind of genetic disease is it most likely to be?

A. Autosomal dominantB. Autosomal recessiveC. Sex-linked dominantD. Sex-linked recessiveE. None of the above

(D)

48. Of people A, B, C, D, who may be carriers for the disease?A. A, BB. B, CC. C, DD. A, DE. None of the above

(B)

49. Alleles recombine during _____ and segregate during _____ in meiosis.A. Metaphase I; Metaphase IIB. Telophase I; Metaphase IIC. Anaphase I; Metaphase ID. Anaphase I; Anaphase IE. None of the above

(E)

50. Snapdragons are flowers that come in a variety of colors, including red, pink, and white. A series of crosses with snapdragons having flowers of different colors produced the following results:

pink × pink: 27 pink, 13 red, 14 whitered × red: all redwhite × white: all whitepink × white: 29 pink, 26 whitepink × red: 28 pink, 27 redwhite × red: all pink

Based on the results, what is the most reasonable explanation for the inheritance of these flower colors?

A. pleiotropic effectsB. incomplete dominanceC. qualitative effectsD. codominanceE. more than two alleles

(B)