AP Bio Chapter 18
1. The coding regions of a gene (the portions that are expressed as polypeptide sequences) are called a. proto-oncogenes. b. introns. c. nucleosomes. d. exons. e. redundant coding sections.
d
10. Proteins that bind to DNA and turn on operons by making it easier for RNA polymerase to bind to a promoter are called a. repressors. b. inhibitors. c. operators. d. activators. e. regulators.
d
13. A homeotic gene a. produces a product that controls the transcription of other genes. b. turns on the genes necessary for synthesis of proteins. c. represses gene transcription. d. serves as a master control gene that functions during embryonic development by controlling the developmental fate of groups of cells. e. All of the choices are correct.
d
11. The lac operon in E. coli a. prevents lactose-utilizing enzymes from being expressed when lactose is absent from the environment. b. coordinates the production of tryptophan-utilizing enzymes when it is present. c. regulates the rate of binary fission. d. uses activators to initiate the production of enzymes that break down lactose. e. allows the bacterium to resist antibiotics in the penicillin family.
a
15. Mutations in the p53 gene can lead to cancer by a. turning off a gene for a protein that inhibits cell division. b. causing the production of excessive amounts of relay proteins. c. increasing the production of growth hormones, which trigger faster cell cycles. d. promoting the expression of mRNA that can interact with DNA, resulting in new mutations. e. increasing the production of glycogen, which nourishes the cell cycle.
a
19. In a prokaryote, a group of genes with related functions, along with their associated control sequences, defines a. an operon. b. a chromosome. c. an allele. d. a transposon. e. a locus.
a
2. The basis of cellular differentiation is a. selective gene expression. b. cellular specialization. c. mutation. d. cloning. e. the operon.
a
20. The expression of the tryptophan operon is controlled by a. a repressor that is active when it binds to tryptophan. b. an activator that turns the operon on by binding to DNA. c. a repressor that is active when it is alone. d. an activator that permanently deletes genes in the tryptophan operon. e. a repressor that is inactive when it binds to lactose.
a
5. The tortoiseshell pattern on a cat a. results from X chromosome inactivation. b. None of the choices are correct. c. is a result of alleles on the Y chromosome. d. is the result of a homozygous recessive condition. e. usually occurs in males.
a
3. The term gene expression refers to the a. fact that individuals of the same species have different phenotypes. b. process by which genetic information flows from genes to proteins. c. fact that certain genes are visible as dark stripes on a chromosome. d. fact that each individual of a species has a unique set of genes. e. flow of information from parent to offspring.
b
4. Most differentiated cells retain a. a complete set of their genes but lose the ability to express most of those genes. b. a complete set of their genes and retain the ability to express those genes under certain circumstances. c. None of the choices are correct. d. only a tiny fraction of their original set of genes but can regenerate lost genes as needed. e. only a tiny fraction of their original set of genes.
b
6. A gene that can cause cancer when present in a single copy in a cell is called a(n) a. enhancer gene. b. oncogene. c. carcinogen. d. proto-oncogene. e. silencer gene.
b
7. The lac operon of E. coli is __________ when the repressor is bound to lactose. a. inactive b. active c. elongated d. cloned e. unregulated
b
9. Which of the following is an example of post-transcriptional control of gene expression? a. gene amplification contributing to cancer b. the removal of introns and alternative splicing of exons c. the folding of DNA to form heterochromatin d. the addition of methyl groups to cytosine bases of DNA e. the binding of transcription factors to the promoter
b
12. Both prokaryotic and eukaryotic cells use which of the following to turn certain genes on or off? a. nucleosome packing. b. DNA ligase. c. regulatory proteins. d. RNA transcriptase. e. intron segments.
c
14. Which of the following processes occurs when a salamander regenerates a lost limb? a. None of the choices are correct. b. A new salamander develops from the lost limb. c. Oncogenes that cause accelerated cell division are turned on. d. Certain cells in the limb dedifferentiate, divide, and then redifferentiate to form a new limb. e. The homeotic genes of the regenerating cells turn off.
d
8. Enhancers are a. required to facilitate the binding of DNA polymerases. b. always adjacent to the gene that they regulate. c. the products of transcription factors. d. the site on DNA to which activators bind. e. required to turn on gene expression when transcription factors are in short supply.
d
17. Cancer of the colon is caused by a. exposure of colon cells to a mutagen. b. lack of vitamin K. c. the proto-oncogene, lac. d. several somatic cell mutations. e. a single gene mutation.
d ?????? I have no idea but it's not e
16. The way that a signal outside a cell triggers changes in the transcription and translation inside the cell is by the process of a. protein breakdown. b. post-transcriptional editing. c. X chromosome inactivation. d. protein activation. e. signal-transduction pathways.
e
18. Evidence suggests that the normal version of the BRCA1 gene is as a(n) __________ gene. a. homeotic b. silencer c. enhancer d. proto-oncogene e. tumor suppressor
e
