大学生物英语测试题.doc

Biol 212 Exam 3Spring 2014, Section 71. Which of the following is UNTRUE? In a multicellular organism different cells become specialized for different functions becauseA. Different cells express different transcriptional regulators.B. Transcriptional regulators are modified differently in different cells.*C. Different cells contain different genes.D. Chromatin conformation varies among different cells.E. DNA is chemically modified differently in different cells.F. None of the above.2. Which is a potential point of gene regulation in eukaryotes but not prokaryotes?A. Transcription*B. RNA processingC. TranslationD. Post-translationE. All are used in both prokaryotes and eukaryotes3. Which of the following is an example of post-translational regulation?A. Intron splicingB. DNA methylation*C. Histone methylationD. RNA polymerizationE. Transcriptional repression4. Which of the following is NOT DIRECTLY involved in transcriptional regulation?A. Enhancer elementsB. Transcriptional repressor proteinsC. DNA methylationD. Chromatin structure*E. G protein coupled receptor activation5. Glucocorticoid “target gene” expression is activated by glucocorticoid hormone becauseA. glucocorticoids activate a receptor kinase that phosphorylates transcription factors.*B. glucocorticoid is a small effector molecule that binds a transcription factor and activates it.C. DNA becomes glucosylated, triggering gene transcriptionD. glucorticoids degrade transcriptional repressorsE. All of the above6. How does DNA methylation usually effect transcription of a gene?A. Enhances transcriptionB. Delays transcription*C. Reduces transcription D. No effect on transcriptionE. Results in methylated mRNA7. If binding of a small effector molecule activates a transcriptional repressor, then increasing concentrations of the effector would result in A. Increased transcription of target genes*B. Decreased transcription of target genesC. Increased transcription of the repressorD. Decreased transcription of the repressorE. A & D8. Histone proteins A. form nucleosomesB. contain a “code” of posttranslational modifications that regulate gene transcriptionC. are important in determining chromatin structureD. interact with DNA to influence accessibility of transcriptional regulators to gene promoters*E. all of the above 9. Combinatorial regulation of gene transcription involves all the following EXCEPTA. chromatin structureB. repressor proteinsC. DNA methylationD. regulatory DNA sequences (elements) near genes*E. second messengers10. Induction of corpus luteum maintenance in the ovary by chorionic gonadotropin hormone from the uterus is an example of A. autocrine signalingB. paracrine signalingC. juxtacrine signaling*D. endocrine signalingE. direct signaling11. Steroid hormones can utilize intracellular receptors because*A. steroid molecules are small and apolar and can freely diffuse through membranesB. responsive cells contain steroid channels that allow the hormone into the cellC. responsive cells contain membrane transporter proteins that bring the hormone into the cellD. in response to a stimulus, steroids are produced inside the cell where they can bind their receptorsE. steroid hormones are transported from cell to cell primarily through gap junctions12. Which of the following is NOT an example of cell signaling?A. Plants changing growth direction in response to light.B. Species recognition among sperm and eggs of marine corals.C. Small effector molecules passing through gap junctions.*D. Formation of tight junctions between epithelial cells.E. Anterior pole specification by the bicoid morphogen in Drosophila13. During development of multicellular organisms, pattern formation involves all the following EXCEPTA. Local cell signaling B. Morphogen concentration gradientsC. Generating the spatial arrangement of cell types or body partsD. Positional information*E. Polycistronic intron splicing14. A protein that changes conformation upon interaction with a signal to trigger a cellular response is called aA. TransporterB. Enzyme*C. ReceptorD. Transcriptional activatorE. Transducer15. Signal transduction refers toA. the transport of hormones in the bloodstreamB. electron transport leading to oxidative phosphorylation*C. a series of events that occur upon receptor activation, leading to a cellular responseD. sequential modifications to the histone codeE. post-translational modifications to a signal ligand16. When activated, receptor kinases are likely toA. enter the cell*B. trigger a protein kinase cascadeC. generate ATPD. bind the extracellular matrixE. exchange GDP for GTP17. All but which of the following are involved in physically holding cells together?*A) G-protein coupled receptors B) anchoring junctionsC) extracellular matrixD) cell adhesion molecules E) middle lamella18. Normal Arabidopsis plants flower in response to long day photoperiods. Upon floral induction, the shoot apical meristem converts to a flower meristem. As shown in the figure, plants that are homozygous for a recessive loss-of-function mutation in the ft gene do not flower in response to photoperiod. What do these results indicate about the function of the normal FT gene? *A. FT is necessary for photoperiod induced flowering.B. FT is sufficient for photoperiod induced flowering.C. The FT gene is necessary AND sufficient for photoperiod induced flowering.D. No conclusion can be drawn from this result.19. In normal plants, expression of the FT gene is activated by long day photoperiod. When the FT coding sequence is placed under the control of a promoter that expresses all the time, the plants flower early, even under non-inductive short day photoperiod. What do these results indicate about the function of the normal FT gene? A. FT is necessary for photoperiod induced flowering.*B. FT is sufficient for photoperiod induced flowering.C. The FT gene is necessary AND sufficient for photoperiod induced flowering.D. No conclusion can be drawn from this result.20. Plants that are homozygous for another recessive loss-of-function mutation in the fd gene also fail to flower in response to photoperiod. Behavior of genetic mosaics with normal leaves and mutant shoot apical meristems (SAMs), or vice versa, is shown below where + indicates the normal gene while indicates mutant.Leaf GenotypeSAM Long day photoperiod responseFT+ft-Floweringft-FT+Does not flowerFD+fd-Does not flowerfd-FD+FloweringThe most likely interpretation of these results is that*A. FT encodes a signal molecule and FD encodes a receptorB. FD encodes a signal molecule and FT encodes a receptorC. FT and FD both encode signal moleculesD. these results indicate neither gene encodes a signaling moleculeE. nothing conclusive can be determined from these results21. Which cell junctions are most similar between plant cells and animal cells.A. tight junctions and middle lamellaB. anchoring junctions and plasmodesmataC. gap junctions and middle lamellaD. anchoring junctions and gap junctions*E. plasmodesmata and gap junctions22. Which of the following provides strong attachments among adjacent animal cells?*A. Anchoring junctionsB. pectinC. tight junctionsD. gap junctionsE. plasmodesmata23. Which of the following is NOT normally associated with the normal progression of development?A. Hierarchies of transcriptional regulationB. Progressive restriction in cell fate*C. Increasing levels of totipotencyD. Cell signaling E. Pattern formation24. Segment identity genesA. are found exclusively in Drosophila and other insects.B. when mutated cause Drosophila embryos to have 2 headsC. are morphogens *D. belong to the HOX gene clusterE. all of the above25. Which of the following is NOT a function for the ECM?*A. Cell secretion B. Cell signalingC. Tissue strengthD. Cell shapeE. Cell connections 26. Stem cells (pick all that are correct):A. produce one multipotent and one univalent daughter *B. are pluripotent in embryos and undergo progressive cell fate restrictionC. undergo programmed cell death*D. can sometimes be reprogrammed E. have not yet shown therapeutic value27. When embryonic stem cells are transplanted into different tissues of a host organism, they commonlyA. migrate to the site from which they were isolatedB. develop into entire embryosC. become hematopoetic*D. differentiate according to signals received from neighboring cellsE. All of the above28. In plant development, the following is NOT true of shoot apical meristems*A. they only occur in embryosB. they involve pattern formation, morphogens, transcriptional hierarchies, progressive restriction of cell fate C. they occur at the tips of shoots and rootsD. they are a self-renewing cell population (like animal stem cells)E. Continually produce organs, tissues, ect.29. Which of the following DOES NOT contribute to the differentiation of stem cell daughters?A. transcriptional hierarchyB. cell signalingC. progressive restriction of cell fate*D. altered genetic contentE. altered gene expression30. Plant development is