Biology Chapter 11

1) The term "gene expression" refers to the

D) process by which genetic information flows from genes to proteins.

2) A gene operon consists of

D) transcribed genes, an operator, and a promoter.

3) In a prokaryote, a group of genes with related functions, along with their associated control sequences, defines

A) an operon.

4) The lac operon in E. coli

C) prevents lactose-utilizing enzymes from being expressed when lactose is absent from the environment.

5) Proteins that bind to DNA and turn on operons by making it easier for RNA polymerase to bind to a promoter are called

D) activators.

6) The lac operon of E. coli is ________ when the repressor is bound to lactose.

A) active

7) The expression of the tryptophan operon is controlled by

D) a repressor that is active when it binds to tryptophan.

8) Which of the following is likely to occur in E. coli cells that are grown in skim milk?

D) The trp repressor is activated and the cells will produce lactose-utilizing enzymes.

9) A single cell, the zygote, can develop into an entirely new organism with many different specialized cells. Which of the following statements about this process is false?

B) Additional genetic information for the formation of specialized cells is passed on to the developing embryo via the placenta.

10) The basis of cellular differentiation is

A) selective gene expression.

11) The genes for the enzymes of glycolysis

A) are active in all metabolizing cells, but the genes for specialized proteins are expressed only in particular cell types.

12) Which of the following statements regarding DNA packing is false?

C) DNA packing tends to promote gene expression.

13) The relationship between DNA and chromosomes is most like

B) thread wrapped around a spool.

14) In female mammals, the inactive X chromosome in each cell

B) becomes a Barr body.

15) The tortoiseshell pattern on a cat

B) results from X chromosome inactivation.

16) Both prokaryotic and eukaryotic cells use ________ to turn certain genes on or off.

D) proteins

17) Enhancers are

A) DNA sequences to which activator proteins bind.

18) Silencers

C) bind to DNA sequences and inhibit the start of transcription.

19) RNA splicing involves the

A) removal of introns from the molecule.

20) The coding regions of a gene (the portions that are expressed as polypeptide sequences) are called

B) exons.

21) Which of the following permits a single gene to code for more than one polypeptide?

C) alternative RNA splicing

22) Small pieces of RNA that can regulate translation of mRNA are called

B) microRNA.

23) miRNA can be used by

B) cells to prevent infections from double-stranded RNA viruses.

24) All of the following mechanisms are used to regulate protein production except

C) DNA editing.

25) Which of the following mechanisms of controlling gene expression occurs outside of the nucleus?

D) translation

26) Which of the following statements about fruit fly development is false?

D) The location of the head and tail ends of the egg is primarily determined by the location of sperm entry during fertilization.

27) A homeotic gene

A) serves as a master control gene that functions during embryonic development by controlling the developmental fate of groups of cells.

28) Which of the following statements about microarrays is false?

A) Microarrays use tiny portions of double-stranded RNA fragments from a large number of genes.

29) In multicellular organisms, the coordination of cellular activities relies on

A) cell-to-cell signaling and signal transduction pathways.

30) To initiate a signal transduction pathway, a signal binds to a receptor protein usually located in the

C) plasma membrane.

31) Transcription factors attach to

D) DNA.

32) A signal outside a cell triggers changes in the transcription and translation inside the cell through

B) signal transduction pathways.

33) Yeast are able to communicate with each other

B) through chemical signaling.

34) Signal transduction pathways

A) are mechanisms of communication that probably evolved in ancient prokaryotes.

35) In plants, most differentiated cells retain

C) a complete set of their genes, and retain the ability to express those genes under certain circumstances.

36) Why can some plants be cloned from a single cell?

D) Plant cells can dedifferentiate and give rise to all of the specialized cells required to produce an entire plant.

37) Which of the following processes occurs when a salamander regenerates a lost limb?

A) Certain cells in the limb dedifferentiate, divide, and then redifferentiate to form a new limb.

38) The cloning of Dolly the sheep

D) demonstrated that the nuclei from differentiated mammalian cells can retain their full genetic potential.

39) The use of cloning to produce special embryonic stem cells is called

B) therapeutic cloning.

40) Which of the following mammals has not yet been cloned and brought through the complete gestation cycle?

A) human

41) Which of the following possible uses of reproductive cloning is still considered by most to be an unresolved ethical issue?

A) the reproductive cloning of humans

42) Which of the following statements regarding stem cells is false?

B) Adult, but not embryonic, stem cells can be grown in laboratory culture.

43) Adult stem cells have limited therapeutic potential

B) because their developmental potential is limited to certain tissues.

44) A gene that can cause cancer when present in a single copy in a cell is called a(n)

A) oncogene.

45) Which of the following statements about proto-oncogenes is false?

B) A mutation in a tumor-suppressor gene can stop cell division immediately.

46) Which of the following is not a factor that contributes to normal cells becoming cancerous?

D) one or more of the cell’s genes being removed by a virus

47) Cancer of the colon is caused by

D) several somatic cell mutations.

48) The development of colon cancer occurs slowly, and colon cancer is more frequently seen in the elderly than the young. This is most likely because

C) four or more somatic mutations must occur to give rise to the cancer, which takes time.

49) Mutations in the proto-oncogene ras and the tumor suppressor gene p53

B) disrupt normal regulation of the cell cycle.

50) Mutations in the p53 gene can lead to cancer by

A) causing the production of a faulty protein that is no longer able to inhibit cell division.

51) The carcinogen known to cause the most cases and types of cancer is

A) tobacco.

52) Which of the following statements regarding cancer risk factors is false?

D) Mutagens are usually not carcinogens.

53) In this drawing of the lac operon, which molecule is an inactive repressor?

D) molecule D

54) Which structure in this figure shows one complete nucleosome?

D) structure D

55) Why don’t the grafted hybrids produce apples with a blend of traits from the scion and the rootstock?

D) The rootstock regulates gene expression in the scion, but contributes no genetic information for fruit production.

56) Half the trees in an orchard were derived from rootstock "A" and half from rootstock "B," but all the
trees had the same scion. If the trees grafted onto rootstock "A" were infected by a parasite that
causes blossom rot, the trees grafted onto rootstock B

A) would be very likely to become infected, because the remaining scions are genetically identical to those that are already infected.

mRNA can be used by

Cells to prevent infections from double-stranded RNA viruses.