Unit 3: Genetics

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Unit 3: Genetics

Multiple Choice

Identify the letter of the choice that best completes the statement or answers the question.

Which of the following statements about genes is incorrect?

a.	Genes correspond to segments of DNA.
b.	Many genes contain the information needed for cells to synthesize enzymes and other proteins.
c.	During fertilization, both the sperm and the ovum contribute genes to the resulting fertilized egg.
d.	Under normal circumstances, each chromosome contains precisely one gene.
e.	Genetic differences can result from changes in the DNA called mutations.

By examining a karyotype, it is possible to determine

a.	which of two related plant forms is a gametophyte, and which is a sporophyte.
b.	the sex of an animal.
c.	the age of a fungus.
d.	A and B only
e.	A, B, and C

For the following questions, match the key event of meiosis with the stages listed below.

I.	prophase I	V.	prophase II
II.	metaphase I	VI.	metaphase II
III.	anaphase I	VII.	anaphase II
IV.	telophase I	VIII.	telophase II

Centromeres of sister chromatids uncouple and chromatids separate.

a.	II
b.	III
c.	IV
d.	V
e.	VII

For a species with a diploid number of 10 chromosomes, how many different combinations of maternal and paternal chromosomes are possible for the gametes?

a.	5
b.	25
c.	32
d.	100
e.	about 10,000

A cross between homozygous purple-flowered and homozygous white-flowered pea plants results in offspring with purple flowers. This demonstrates

a.	the blending model of genetics.
b.	true-breeding.
c.	dominance.
d.	a dihybrid cross.
e.	the mistakes made by Mendel.

In a cross AaBbCc

AaBbCc, what is the probability of producing the genotype AABBCC?

a.	1/4
b.	1/8
c.	1/16
d.	1/32
e.	1/64

If doubly heterozygous SsNn cactuses were allowed to self-pollinate, the F2 would segregate in which of the following ratios?

a.	3 sharp-spined : 1 spineless
b.	1 sharp-spined : 2 dull-spined : 1 spineless
c.	1 sharp spined : 1 dull-spined : 1 spineless
d.	1 sharp-spined : 1 dull-spined
e.	9 sharp-spined : 3 dull-spined : 4 spineless

The pedigree chart below is for a family, some of whose members exhibit the recessive trait, wooly hair. Affected individuals are indicated by an open square or circle. Use the chart to answer the following questions.

What is the genotype of individual B-5?

a.	WW
b.	Ww
c.	ww
d.	WW or ww
e.	ww or Ww

The improvement of microscopy techniques in the late 1800s set the stage for the emergence of modern genetics because

a.	it revealed new and unanticipated features of Mendel's pea plant varieties.
b.	it allowed biologists to study meiosis and mitosis, revealing the parallels between the behaviors of genes and chromosomes.
c.	it allowed scientists to see the DNA present within chromosomes.
d.	it led to the discovery of mitochondria.
e.	All of the above are true.

The following questions refer to the data and figures below.

CROSS I. Purebred lines of wild-type fruit flies (gray body and normal wings) are mated to flies with black bodies and vestigial wings.

F1 offspring all have a normal phenotype.

CROSS II. F1 flies are crossed with flies recessive for both traits (a testcross).

Resulting Offspring	Normal	Percentage
Gray body; normal wings	575	25.1
Black body; vestigial wings	571	24.9
Black body; normal wings	577	25.2
Gray body; vestigial wings	568	24.8

KEY:

A. CROSS I results give evidence supporting the statement.

B. CROSS I results give evidence against the statement.

C. CROSS II results give evidence supporting the statement.

D. CROSS II results give evidence against the statement.

E. Neither CROSS I nor CROSS II results support the statement.

10.

An F1 cross should produce flies that will fall into a Mendelian 9:3:3:1 ratio.

a.	A
b.	B
c.	C
d.	D
e.	E

11.

SRY is

a.	a gene present on the Y chromosome that triggers male development.
b.	a gene present on the X chromosome that triggers female development.
c.	an autosomal gene that is required for the expression of genes on the Y chromosome.
d.	an autosomal gene that is required for the expression of genes on the X chromosome.
e.	required for development, and males or females lacking the gene do not survive past early childhood.

12.

One possible result of chromosomal breakage is for a fragment to join a nonhomologous chromosome. This is called a (an)

a.	deletion.
b.	disjunction.
c.	inversion.
d.	translocation.
e.	duplication.

13.

The pedigree in the figure below shows the transmission of a trait in a particular family. Based on this pattern of transmission, the trait is most likely

a.	mitochondrial.
b.	autosomal recessive.
c.	sex-linked dominant.
d.	sex-linked recessive.
e.	autosomal dominant.

14.

What does transformation involve in bacteria?

a.	the creation of a strand of DNA from an RNA molecule
b.	the creation of a strand of RNA from a DNA molecule
c.	the infection of cells by a phage DNA molecule
d.	the type of semiconservative replication shown by DNA
e.	assimilation of external DNA into a cell

15.

The DNA double helix has a uniform diameter because ____, which have two rings, always pair with ____, which have one ring.

a.	purines; pyrimidines
b.	pyrimidines; purines
c.	deoxyribose sugars; ribose sugars
d.	ribose sugars; deoxyribose sugars
e.	nucleotides; nucleoside triphosphates

16.

What determines the nucleotide sequence of the newly synthesized strand during DNA replication?

a.	the particular DNA polymerase catalyzing the reaction
b.	the relative amounts of the four nucleoside triphosphates in the cell
c.	the nucleotide sequence of the template strand
d.	the primase used in the reaction
e.	both A and D

17.

Individuals with the disorder xeroderma pigmentosum are hypersensitive to sunlight because their cells have an impaired ability to

a.	replicate DNA.
b.	undergo mitosis.
c.	exchange DNA with other cells.
d.	repair thymine dimers.
e.	recombine homologous chromosomes during meiosis.

The following questions refer to the following simple metabolic pathway:

enzyme A	enzyme B

18.

If A, B, and C are all required for growth, a strain that is mutant for the gene encoding enzyme A would be able to grow on which of the following media?

a.	minimal medium
b.	minimal medium supplemented with nutrient "A"
c.	minimal medium supplemented with nutrient "B"
d.	minimal medium supplemented with nutrient "C"
e.	Answers C and D are correct.

Use the table of condons below to answer the following questions.

19.

A peptide has the sequence NH2-phe-pro-lys-gly-phe-pro-COOH. Which of the following sequences in the coding strand of the DNA codes for this peptide?

a.	3' UUU-CCC-AAA-GGG-UUU-CCC
b.	3' AUG-AAA-GGG-TTT-CCC-AAA-GGG
c.	5' TTT-CCC-AAA-GGG-TTT-CCC
d.	5' GGG-AAA-TTT-AAA-CCC-ACT-GGG
e.	5' ACT-TAC-CAT-AAA-CAT-TAC-UGA

20.

Which of the following is not a part of the eukaryotic transcription initiation complex?

a.	promoter
b.	RNA polymerase
c.	transcription factors
d.	snRNP
e.	TATA box

21.

A transcription unit that is 8,000 nucleotides long may use 1,200 nucleotides to make a protein consisting of 400 amino acids. This is best explained by the fact that

a.	many noncoding nucleotides are present in mRNA.
b.	there is redundancy and ambiguity in the genetic code.
c.	many nucleotides are needed to code for each amino acid.
d.	nucleotides break off and are lost during the transcription process.
e.	there are termination exons near the beginning of mRNA.

22.

A part of an mRNA molecule with the following sequence is being read by a ribosome: 5' CCG-ACG 3' (mRNA). The following activated transfer RNA molecules (with their anticodons shown in the 3' to 5' direction) are available. Two of them can correctly match the mRNA so that a dipeptide can form.

tRNA Anticodon	Amino Acid
GGC	Proline
CGU	Alanine
UGC	Threonine
CCG	Glycine
ACG	Cysteine
CGG	Alanine

The dipeptide that will form will be

a.	cysteine-alanine.
b.	proline-threonine.
c.	glycine-cysteine.
d.	alanine-alanine.
e.	threonine-glycine.

23.

As a ribosome translocates along an mRNA molecule by one codon, which of the following occurs?

a.	The tRNA that was in the A site moves into the P site.
b.	The tRNA that was in the P site moves into the A site.
c.	The tRNA that was in the P site moves to the E site and is released.
d.	The tRNA that was in the A site departs from the ribosome.
e.	Both A and C are correct.

24.

Which of the following is (are) true about RNA?

a.	snoRNA aids in processing pre-rRNA transcripts in the nucleolus.
b.	SRP RNA is an essential component of spliceosomes.
c.	It has functional groups that allow it to act as a catalyst (ribozyme).
d.	Only A and C are true.
e.	A, B, and C are true.

25.

Which of the following statements are true about protein synthesis in prokaryotes?

a.	Translation can begin while transcription is still in progress.
b.	Extensive RNA processing is required before prokaryotic transcripts can be translated.
c.	Prokaryotic cells have complicated mechanisms for targeting proteins to the appropriate cellular organelles.
d.	Only A and B are true.
e.	A, B, and C are true.

26.

Which of the above is analogous to a single substitution mutation?

a.	A
b.	B
c.	C
d.	D
e.	E

27.

A researcher lyses a cell that contains nucleic acid molecules and capsomeres of tobacco mosaic virus (TMV). The cell contents are left in a covered test tube overnight. The next day this mixture is sprayed on tobacco plants. Which of the following would be expected to occur?

a.	The plants would develop some but not all of the symptoms of the TMV infection.
b.	The plants would develop symptoms typically produced by viroids.
c.	The plants would develop the typical symptoms of TMV infection.
d.	The plants would not show any disease symptoms.
e.	The plants would become infected, but the sap from these plants would be unable to infect other plants.

28.

RNA viruses appear to have higher rates of mutation because

a.	RNA nucleotides are more unstable than DNA nucleotides.
b.	replication of their genomes does not involve the proofreading steps of DNA replication.
c.	RNA viruses replicate faster.
d.	RNA viruses can incorporate a variety of nonstandard bases.
e.	RNA viruses are more sensitive to mutagens.

Use the following answers for the following questions. The answers may be used once, more than once, or not at all.

A. transduction

B. transposition

C. translation

D. transformation

E. conjugation

29.

DNA is transferred from one bacterium to another by a virus.

a.	A
b.	B
c.	C
d.	D
e.	E

For the following questions, match the terms below with the appropriate phrase or description below. Each term can be used once, more than once, or not at all.

A. operon

B. inducer

C. promoter

D. repressor

E. corepressor

30.

This protein is produced by a regulatory gene.

a.	A
b.	B
c.	C
d.	D
e.	E

31.

Which of the following statements concerning the eukaryotic chromosome is false?

a.	It is composed of DNA and protein.
b.	The nucleosome is the most basic structural subunit.
c.	The number of genes on each chromosome is different in different cell types.
d.	It consists of a single linear molecule of double-stranded DNA.
e.	Active transcription occurs on euchromatin.

32.

If you were to observe the activity of methylated DNA, you would expect it to

a.	be replicating.
b.	be unwinding in preparation for protein synthesis.
c.	have turned off or slowed down the process of transcription.
d.	be very active in translation.
e.	induce protein synthesis by not allowing repressors to bind to it.

Use the terms below to answer the following questions. Each term may be used once, more than once, or not at all.

A. enhancer

B. promoter

C. activator

D. repressor

E. terminator

33.

site in the DNA located near the end of the final exon, encoding an RNA sequence that determines the 3' end of the transcript

a.	A
b.	B
c.	C
d.	D
e.	E

34.

The Ras protein is involved in ____, and cancer-causing forms of the protein are usually ____.

a.	relaying a signal from a growth factor receptor; hyperactive
b.	DNA replication; nonfunctional
c.	DNA repair; hyperactive
d.	cell-cell adhesion; nonfunctional
e.	cell division; nonfunctional

Use the terms below to answer the following questions. Each term may be used once, more than once, or not at all.

A. transposons

B. simple sequence DNA

C. multigene family

D. methylated DNA

E. pseudogenes

35.

This class of DNA codes for the three largest ribosomal RNA molecules.

a.	A
b.	B
c.	C
d.	D
e.	E

The table below indicates the exons present in six different genes. Gene 1, for example, contains exons A, B, C, and D, in this order, and gene 2 has a similar structure, although exons A and B have been replaced by related but distinct versions called A' and B'.

Gene	Exons
1	A-B-C-D
2	A'-B'-C-D
3	A-B'-C-D
4	A-A-B-C-D
5	A-B-C-D'
6	E-F-B-G

36.

The structural similarity seen in genes 1 through 5 suggests that they were most likely produced by

a.	gene duplication.
b.	exon shuffling.
c.	exon duplication.
d.	translocation.
e.	polyploidy.

37.

Which enzyme was used to produce the molecule in the figure below?

a.	ligase
b.	transcriptase
c.	a restriction enzyme
d.	RNA polymerase
e.	DNA polymerase

38.

The polymerase chain reaction is important because it allows us to

a.	insert eukaryotic genes into prokaryotic plasmids.
b.	incorporate genes into viruses.
c.	make DNA from RNA transcripts.
d.	make many copies of a targeted segment of DNA.
e.	insert regulatory sequences into eukaryotic genes.

39.

DNA fragments from a gel are transferred to a nitrocellulose paper during the procedure called Southern blotting. The purpose of transferring the DNA from a gel to a nitrocellulose paper is to

a.	permanently attach the DNA fragments to a substrate.
b.	separate the two complementary DNA strands.
c.	transfer only the DNA that is of interest.
d.	prepare the DNA for digestion with restriction enzymes.
e.	separate out the PCRs.

40.

Dideoxyribonucleotide chain-termination is a method of

a.	cloning DNA.
b.	sequencing DNA.
c.	digesting DNA.
d.	synthesizing DNA.
e.	separating DNA fragments.

41.

DNA microarrays have made a huge impact on genomic studies because they

a.	can be used to eliminate the function of any gene in the genome.
b.	can be used to introduce entire genomes into bacterial cells.
c.	allow the expression of many or even all of the genes in the genome to be compared at once.
d.	allow physical maps of the genome to be assembled in a very short time.
e.	dramatically enhance the efficiency of restriction enzymes.

42.

Gene therapy

a.	has proven to be beneficial to HIV patients.
b.	involves replacement of a defective allele in sex cells.
c.	cannot be used to correct genetic disorders.
d.	had apparent success in treating disorders involving bone marrow cells.
e.	is a widely accepted procedure.

43.

Which of the following are common model organisms in the study of developmental genetics?

a.	Homo sapiens
b.	Drosophila melanogaster
c.	Arabidopsis thaliana
d.	B and C only
e.	A, B, and C

44.

One striking difference between development in plants and development in animals is that in plant development

a.	growth and morphogenesis continue throughout the life of the plant.
b.	cell differentiation never stops.
c.	once a structure develops, it cannot reverse its path.
d.	cell differentiation is rarely permanent.
e.	chemical signals play a much greater role than in animal development.

45.

In cloning, the ability of a transplanted nucleus to support development

a.	is inversely related to the age of the donor.
b.	depends on the DNA base sequence.
c.	only occurs in plants.
d.	depends on the size of the genome.
e.	depends on the nucleus not changing.

Use the responses below to answer the following questions:

A. homeotic genes

B. segmentation genes

C. egg-polarity genes

D. morphogens

E. inducers

46.

Mutations in these genes lead to transformations in the identity of entire body parts.

a.	A
b.	B
c.	C
d.	D
e.	E

47.

Which of the following are true statements about homeobox-containing genes?

a.	They are found in both plants and animals.
b.	They are involved in the transcriptional regulation of other genes.
c.	They encode proteins containing domains called "homeodomains."
d.	Only B and C are true.
e.	A, B, and C are true.