Fall 2011 Midterm Exam

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Biology 105Midterm Examination II Version AFall 2011

This was the second midterm examination of the course in the Fall of 2011. Be mindful that one instructor was different, and the materials covered and emphasized were slightly different. Some questions here may concern areas not discussed in the current semester.

1. Bacteria typically have _______, whereas eukaryotes have _______.a. one chromosome that is circular; many chromosomes that are linear.b. several chromosomes that are circular; many chromosomes that are linear.c. one chromosome that is linear; many chromosomes that are circular.d. two chromosomes that are circular; eight chromosomes that are linear.e. None of the above.

2. Mature nerve cells, which are incapable of cell division, are most likely in:a. G1.b. the S phase.c. G2.d. mitosis.e. meiosis.

3. A typical cell cycle consists of:a. mitosis and meiosis.b. G1, the S phase, and G2.c. prophase, metaphase, anaphase, and telophase.d. interphase, mitosis, and cytokinesis.e. meiosis and fertilization.

4. The molecules that make up a chromosome are _______ and _______.a. DNA; RNAb. DNA; proteinsc. proteins; lipidsd. nucleotides; nucleosidese. proteins; phospholipids

5. The basic structure of chromatin has sometimes been referred to as beads on a string of DNA. These beads are called:a. chromosomes.b. chromatids.c. supercoils.d. interphases.e. nucleosomes.

6. The products of mitosis are:a. one nucleus containing twice as much DNA as the parent nucleus.b. two genetically identical cells.c. four nuclei containing half as much DNA as the parent nucleus.d. four genetically identical nuclei.e. two genetically identical nuclei.

7. Many chromosome abnormalities (trisomies and monosomies) are not observed in the human population because:a. they are lethal and cause spontaneous abortion of the embryo early in development.b. all trisomies and monosomies are lethal early in childhood.c. meiosis distributes chromosomes to daughter cells with great precision.d. they are so difficult to count.e. the human meiotic spindle is self-correcting.

8. Different forms of a gene are called:a. traits.b. phenotypes.c. genotypes.d. alleles.e. None of the above

9. In a(n) _______ cross, genes for two different characters separate.a. monohybridb. dihybridc. trihybridd. F1e. F2

10. Classical albinism results from a recessive allele. Which of the following is the expected ratio for the progeny when a normal pigmented male with an albino father has children with an albino woman?a. 34normal; 14 albinob. 34albino; 14 normalc. 12normal; 12 albinod. All normale. All albino

11. A pea plant with red flowers is test crossed, and one-half of the resulting progeny have red flowers, while the other half has white flowers. Therefore, the genotype of the test-crossed parent was:a. RR.b.Rr.c. rr.d. eitherRR orRr.e. This cannot be answered without more information.

12. The genetic disease blue sclera is determined by an autosomal dominant allele. The eyes of individuals with this allele have bluish sclera. These same individuals may also suffer from fragile bones and deafness. This is an example of:a. incomplete dominance.b. pleiotropy.c. epistasis.d. codominance.e. linkage.

13. A linkage group corresponds to:a. a group of genes on different chromosomes.b. the linear order of centromeres on a chromosome.c. the length of a chromosome.d. a group of genes on the same chromosome.e. None of the above

14. What is the pattern of inheritance for a rare dominant allele?a. Every affected person has an affected parent.b. Unaffected parents can produce children who are affected.c. Affected parents do not produce affected children.d. Unaffected mothers have affected sons and daughters who are carriers.e. None of the above

15. Chargaffs rule states that:a. DNA must be replicated before a cell can divide.b. viruses enter cells without their protein coat.c. only protein from the infecting phage can also be detected in progeny phage.d. only nucleic acids enter the cell during infection.e. the amount of cytosine equals the amount of guanine.

16. The strands that make up DNA are antiparallel. This means that:a. one strand is positively charged, and the other is negatively charged.b. the base pairings create unequal spacing between the two DNA strands.c. the 5-to-3 direction of one strand is counter to the 5-to-3 direction of the other strand.d. the twisting of the DNA molecule has shifted the two strands.e. purines bond with purines and pyrimidines bond with pyrimidines.

17. Mutations are:a. heritable changes in the sequence of DNA bases that produce an observable phenotype.b. heritable changes in the sequence of DNA bases.c. mistakes in the incorporation of amino acids into proteins.d. heritable changes in the mRNA of an organism.e. None of the above

18. At the end of DNA replication, two DNA molecules are produced, each one consisting of a parental DNA strand and a new DNA strand. This process is known as:a. semiconservative replication.b. conservative replication.c. dispersive replication.d. fission.e. the transforming principle.

19. Ideally, PCR _______ increases the amount of DNA during additional cycles.a. additivelyb. graduallyc. linearlyd. systematicallye. exponentially

20. One strand of DNA has the sequence 5-ATTCCG-3 The complementary strand for this is:a. 5-TAAGGC-3b. 5-ATTCCG-3c. 5-ACCTTA-3d. 5-CGGAAT-3e. 5-GCCTTA-3

21. After irradiating Neurospora, Beadle and Tatum collected mutants that would:a. not grow on a minimal medium but would grow on a minimal medium with arginine.b. grow on any minimal medium.c. not grow on any minimal medium.d. grow on a minimal medium but would not grow on a minimal medium with arginine.e. None of the above

22. The central dogma of molecular biology states that:a. information flow between DNA, RNA, and protein is reversible.b. information flow in the cell is unidirectional, from protein to RNA to DNA.c. information flow in the cell is unidirectional, from DNA to RNA to protein.d. the DNA sequence of a gene can be predicted if we know the amino acid sequence of the protein it encodes.e. the genetic code is ambiguous but not degenerate.

23. Imagine that a novel life-form is found deep within Earths crust. Evaluation of its DNA yields no surprises. However, it is found that a codon for this life-form is just two bases in length. How many different amino acids could this organism be composed of?a. 4b. 8c. 16d. 32e. 64

24. Exons are:a. spliced out of the original transcript.b. spliced together from the original transcript.c. spliced to introns to form the final transcript.d. much larger than introns.e. larger than the original coding region.

25. The binding of snRNPs to consensus sequences is necessary for:a. gene duplication.b. the addition of a poly A tail.c. capping an hnRNA.d. RNA splicing.e. transcription.

26. What events must take place to ensure that the protein made is the one specified by mRNA?a. tRNA must read mRNA correctly.b. tRNA must carry the amino acid that is correct for its reading of the mRNA.c. Covalent bonding between the base pairs must occur.d. Both a and be. All of the above

27. mRNA is synthesized in the _______ direction, which corresponds to the _______ of the protein.a. 5 to 3; N terminus to C terminusb. 3 to 5; C terminus to N terminusc. 5 to 3; C terminus to N terminusd. 3 to 5; N terminus to C terminuse. Examples of all of the above have been found.

28. The three basic parts of an operon are the:a. promoter, the operator, and two or more structural genes.b. promoter, the structural genes, and the termination codons.c. promoter, the mRNA, and the termination codons.d. structural genes, the mRNA, and the tRNAs.e. None of the above

29. Which operon is turned off in response to molecules present in the environment of the cell?a. Repressibleb. Suppressiblec. Impressibled. Induciblee. Degraded

30. Which of the following is not a DNA binding motif?a. Helix-straight-helixb. Helix-turn-helixc. Helix-loop-helixd. Leucine zippere. Zinc finger

31. The drought stress response in plants is an example of:a. a transcription factor.b. coordinated gene expression.c. a way to increase water intake.d. Both a and be. None of the above

32. The interphase cells of normal female mammals have a stainable nuclear body called a Barr body. This body is:a. an inactive X chromosome.b. made of fat droplets.c. made of fragments of mRNA.d. made of extra chromosomal pieces.e. None of the above

33. A chemical modification that adds methyl groups to cytosine residues in some genes acts to:a. enhance transcription.b. amplify the gene.c. inactivate the gene.d. stabilize the mRNA.e. None of the above

34. What would happen initially to cells that lack a functional ubiquitin?a. Nothing would happen.b. Transcriptional initiation would increase.c. Protein degradation would decrease.d. Histone modifications would increase.e. Translation of proteins would be more efficient.

35. Which of the following is the correct ranking of stem cells with respect to the number of cell types into which they can differentiate (from greatest to least)?a. Multipotent> pluripotent > totipotentb. Pluripotent > totipotent >multipotentc. Pluripotent >multipotent> totipotentd. Totipotent > pluripotent >multipotente. Totipotent >multipotent> pluripotent

36. The process by which signaling molecules from one tissue (or group of cells) affect the development of adjacent tissue is called:a. determination.b. morphogenesis.c. placode.d. differentiation.e. induction.

37. The large amount of yolk in birds eggs results in:a. gradual metamorphosis.b. complete metamorphosis.c. incomplete cleavage.d. incomplete mitosis during cleavage.e. bicoid larvae.

38. After gastrulation, the endodermal cells contribute predominantly to the developing:a. brain, nervous system, and nails.b. skeletal system and muscles.c. lining of the digestive and respiratory tracts.d. sweat glands and milk secretory glands.e. None of the above

39. If the blastopore dorsal lip is grafted from one frog embryo onto a second embryo, the second dorsal lip will:a. change the polarity of the adjacent segments.b. block gastrulation.c. change the developmental fate of the surrounding cells.d. change the prospective potency of the surrounding cells.e. cause rapidcell division.

40. The structure in birds and mammals that is most analogous to the dorsal lip of the frog blastopore is:a. the primitive streak.b. the archenteron.c. the yolk plug.d. Hensens node.e. the notochord.

41. Which if the following is an example of homeostasis?a. Blood meal stimulation of molting in Rhodnius.b. The evolution of big ears in elephants.c. A chipmunk hibernating in the winter.d. Inactivation of the lac operon when glucose is available.e. None of the above.

42. Animal A has a higher surface-area-to-volume ratio than Animal B. We are safe to conclude from this that:a. Animal B is likely to have a higher basal metabolic rate than Animal A.b. Animal A is likely to have a higher basal metabolic rate than Animal B.c. Animals A has larger ears than Animals B.d. Animal A is a tropical animal; Animal B is an arctic animal.e. Animal B has a higher tendency to gain heat from the environment than Animal A.

43. Heat is generated in brown fat by:a. the breakdown of ATP.b. the metabolism of thermogenin.c. an inefficient glycolysis pathway.d. the burning of stored fat as a source of energy.e. converting potential energy stored in proton gradient to thermal energy.

44. Which of the following statement regarding Q10 is incorrect?a. heterothermic animals tend to have higher Q10s than homeothermic animals.b. different metabolic activities may have different Q10s.c. a metabolic activity with a Q10 of 1 is temperature-independent.d. Q10 is a measure of how metabolic reactions depend on temperature.e. among animals, it is unusual to find Q10s greater than 4.

45. In response to an infection, the body usually generates a fever. The first step the thermoregulatory system takes is to:a. reduce blood flow to the skin.b. shut off internal cooling mechanisms.c. increase metabolic activity in brown fat.d. ramp up the basal metabolic rate.e. resetting the hypothalamic set point.

46. Which of the following observations is the strongest piece of evidence that the thermostat in homeotherms resides in the hypothalamus?a. When the hypothalamus is heated, body temperature increases.b. The temperature of the hypothalamus is always 37C.c. The temperature of the hypothalamus changes with the rest of the body.d. Heterothermic animals do not have hypothalamus.e. Direct cooling of the hypothalamus results in an increase in body temperature.

47. The thermoneutral zone is:a. the part of the body that is 37C.b. where heat gain equals heat loss.c. temperature between the freezing point of water and the denaturing temperature of proteins.d. the range of ambient temperature within which metabolic thermoregulation is not necessary.e. the range of ambient temperature within which the Q10 of most metabolic reactions is close to 2.

48. Which of Vincent Wigglesworths observations of Rhodnius supports the idea that molting is mediated by a diffusible substance?a. when two bugs are connected together, the unfed bug does not inhibit molting of the one that had been fed.b. when two bugs are connected, the feeding status of one can trigger molting in the other.c. if decapitated immediately following a blood meal, the bug will not molt.d. molting is independent of the age of the bug.e. when a bug is decapitated, it always molts into an adult.

49. Cortisol feedback inhibition of adrendocorticotropic hormone serves to:a. prevent excessive secretion of corticotrophin releasing hormone.b. maintain a steady state level of cortisol.c. reduce the stressful stimulus.d. inhibit the action of cortisol on its target cells.e. terminate the stress response.

50. A paracrine hormone is a hormone:a. that acts on adjacent target cells.b. that relies on the circulatory system for delivery.c. that is synthesized and released by the parathyroid gland.d. that does not need a hormone receptor in order to act.e. that has the same action on all its target cells.

51. Insecticide manufacturers invest heavily in discovering chemicals that mimic or antagonize the action of these hormones. What might be the effects of a chemical that mimics ecdysone?a. it will prevent insect molting.b. it will promote inappropriate molting.c. it will accelerate metamorphosis and produce miniature adults.d. it will produce large, immature insects.e. it will produce adults with larval features.

52. Hypercalcemia is an excess of plasma calcium. In a healthy individual, what is the principal mechanism(s) that prevents an elevation of calcium in circulation?a. calcitonin inhibits the release of parathyroid hormone.b. parathyroid hormone stimulation of calcium excretion by the kidne...

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