Deck 6: Transmission Genetics and the Sources of Genetic Variation

Question 1

The law of independent assortment states which of the following?

A) characters are blended in hybrid offspring
B) purple-flowered plants will never produce white-flowered offspring
C) the allele passed down to the next generation at one locus is independent of the allele passed down at a second locus
D) alleles from two separate loci, once combined in a hybrid, cannot be separated in future reproductive events

Answer 1

C

Question 2

Proteins consist of long chains of ________ linked together.

A) nitrogenous bases
B) amino acids
C) mRNA
D) codons

Answer 2

B

Question 3

Which of the following statements regarding the difference between RNA and DNA is true?

A) Only RNA uses guanine.
B) Only RNA uses cytosine.
C) Only RNA uses adenine.
D) Only RNA uses uracil.

Answer 3

D

Question 4

Why did the pre-Mendelian theory of blending inheritance pose a major challenge to Charles Darwin's theory of evolution by natural selection?

A) Blending inheritance would eliminate variation in a population.
B) With blending inheritance, genes are passed down across generations even when they are not visibly expressed in offspring.
C) The hereditary determinants of phenotype are particulate.
D) Blending inheritance does not challenge Darwin's theory of natural selection.

Question 5

Which of the following statements is FALSE?

A) Epigenetic changes play important roles in organismal development, such as during cell differentiation.
B) Epigenetic information cannot be passed down across generations.
C) Epigenetic changes during prenatal development or early in life are responsible for aspects of developmental plasticity.
D) Most epigenetic changes to the genome are reset at each generation.

Question 6

DNA molecules can be very long. To better pack them into cells, DNA is often

A) reduced to a single strand.
B) coiled around proteins called histones.
C) broken into smaller molecules.
D) equally divided between neighboring cells.

Question 7

By what process does the cell construct proteins from mRNA sequences?

A) transcription
B) recombination
C) splicing
D) translation

Question 8

The observation that hybrid offspring of "true-breeding" purple-flowered plants crossed with "true-breeding" white-flowered plants are purple in color can be explained by the

A) dominance of the purple color.
B) blending of parental characters.
C) law of independent assortment.
D) incomplete dominance of the white color.

Question 9

Nucleotide sequences of a gene that code for protein products (as opposed to noncoding regions) are known as

A) mRNA.
B) introns.
C) exons.
D) codons.

Question 10

How many copies of each chromosome does a tetraploid organism have in its somatic cells?

A) one
B) two
C) four
D) eight

Question 11

With no mutation, an mRNA sequence reads "UCA," which codes for serine. A mutation arises that changes the sequence to "UCC," which codes for serine. This is an example of all of the following types of mutation EXCEPT

A) point mutation.
B) synonynous mutation.
C) transversion.
D) nonsense mutation.

Question 12

A change in allele frequency at one locus does not result in the change in allele frequency at a second locus. These loci are most likely

A) recessive.
B) unlinked.
C) linked.
D) dominant.

Question 13

For the DNA sequence 5'-ACG TTA -3', what would be the complementary RNA sequence? (Remember that the DNA template and the mRNA strands are antiparallel.)

A) 5'-TGC AAT-3'
B) 5'-UGC AAU-3'
C) 5'-TAA CGT-3'
D) 5'-UAA CGU-3'

Question 14

________ are regulatory elements that affect genes at nearby sites on the same chromosome.

A) Cis regulatory elements
B) Trans regulatory elements
C) Enhancers
D) Silencers

Question 15

What is RNA that directs protein synthesis through the processes of transcription and translation called?

A) ribosomal RNA
B) microRNA
C) messenger RNA
D) transfer RNA

Question 16

DNA is tightly wound in a double helix for much of the time. Which of the following enzymes unwinds the double helix and begins transcription of RNA?

A) RNA polymerase
B) DNA polymerase
C) transcriptase
D) RNA isomerase

Question 17

Using the figure, which of the amino acid sequences would be generated from the RNA sequence: CGA GGC UUA ACG (read in the 3' direction)?

A) arginine; glycine; leucine; threonine
B) arginine; glycine; phenylalanine; threonine
C) serine; glycine; isoleucine; threonine
D) serine; arginine; isoleucine; serine

Question 18

Which of the following statements is FALSE?

A) Most prokaryotes have a single circular chromosome.
B) Most eukaryotes have multiple linear chromosomes.
C) Diploid organisms have two copies of each chromosome.
D) Haploid organisms have more than two copies of each chromosome.

Question 19

Gregor Mendel's law of segregation states that

A) each diploid individual has two copies of every gene, and that the two gene copies separate with equal probability into the individual's gametes.
B) two copies of each gene are found in a gamete.
C) traits from each parent are permanently blended in their offspring.
D) the allele passed down to the next generation at one locus is independent of which allele is passed down at another locus.

Question 20

Which of the following is FALSE regarding DNA?

A) DNA is a polymer composed primarily of repeating five carbon sugars.
B) DNA contains four types of nitrogenous bases.
C) DNA consists of two strands of nucleotides connected by hydrogen bonds.
D) DNA nitrogenous bases can each pair with any other base.

Question 21

Based on the figure shown, which of the following statements is FALSE? A


B

A) RNA viruses have greater base substitution rates than DNA viruses.
B) Invertebrates have greater base substitution mutation rates than mammals.
C) Eubacteria have greater base substitution rates than Archaeans.
D) Unicellular eukaryotes have greater base substitution rates than Eubacteria.

Question 22

In a(n) ________ mutation, part of a chromosome is transferred to a nonhomologous chromosome.

A) duplication
B) inversion
C) translocation
D) deletion

Question 23

Which of the mutations in the figure depicts a nonsense mutation?

A) Mutation A
B) Mutation B
C) Mutation C
D) A nonsense mutation is not pictured.

Question 24

A researcher follows the mutation rates in the nematode Caenorhabditis elegans in five different tissue types across 300 generations. One would expect mutation rates across the different tissue types to be

A) equal.
B) approximately equal.
C) different.
D) neutral with respect to fitness.

Question 25

Where on a DNA molecule would you expect to find genes that are unexpressed?

A) where the chromatin is decondensed
B) where RNA polymerase binds to the promoter
C) where the chromatin is condensed
D) where there are histones

Question 26

Why is RNA more likely than DNA to get damaged during chemical reactions?

Question 27

How many cross-over events are depicted in the figure?

A) zero
B) one
C) two
D) four

Question 28

Which of the diagrams shown illustrates an inversion? A


B


C


D

A) A
B) B
C) C
D) D

Question 29

If an RR flower is red, an Rr flower is pink, and an rr flower is white, what percentage of the offspring from a cross between an RR individual and an Rr individual will be red?

A) 10%
B) 25%
C) 50%
D) 75%

Question 30

The double strands of DNA separate from each other at high temperatures. Why do G-C rich strands of DNA require a relatively higher temperature to separate?

Question 31

Regulatory elements

A) are always found close to the gene they regulate.
B) control the rate of mRNA production.
C) are found only in prokaryotes.
D) have no effect on phenotype.

Question 32

What is epigenetic inheritance, and how do epigenetic changes play a role in organismal development?

Question 33

All of the offspring from a cross between an RR plant and an rr plant (RR x rr) will be ________ for the "R" gene.

A) dominant
B) recessive
C) homozygotic
D) heterozygotic

Question 34

Crossing-over

A) involves the physical exchange of parts of homologous chromosomes.
B) occurs during mitosis.
C) involves the fusion of gametes to restore the diploid number of chromosomes.
D) occurs in somatic cells.

Question 35

Many trans-acting regulatory elements reside on a separate chromosome from the genes that they regulate. In such cases, the regulatory element is ________, relative to the gene.

A) unlinked
B) linked
C) dominant
D) recessive

Question 36

Describe the manner in which DNA is packed into the nucleus of eukaryotic cells. Include information about the structure of DNA within nuclei and how its structure affects gene expression.

Question 37

If two alleles generate a heterozygote phenotype that is intermediate between the homozygotes for each allele, the alleles are said to exhibit

A) complete dominance.
B) incomplete dominance.
C) recessive characteristics.
D) blending.

Question 38

Based on the Punnett square shown here, assume the parental generation cross of Tt x tt is shown. If the heterozygous F₁ offspring cross (Tt x Tt), what are the predicted offspring genotype frequencies? What proportion of the offspring (F₂ generation) would you expect to be "short"?

Question 39

Which of the following statements is true?

A) Most mutations are either neutral or deleterious with respect to fitness.
B) Most mutations are beneficial with respect to fitness.
C) In order for fitness to be affected, a mutation must affect a large portion of a gene.
D) Only a small fraction of mutations are lethal.

Question 40

Which of the following statements is FALSE?

A) Gregor Mendel examined seven different characters of pea plants, including flower color.
B) Gregor Mendel came to two important conclusions from his experiments on pea plants, and these are known as Mendel's laws.
C) Gregor Mendel's work went relatively undiscovered until around 1900.
D) Gregor Mendel and Charles Darwin were colleagues.

Question 41

List and describe the three most common parts of a protein-coding eukaryotic gene.

Question 42

When comparing the DNA sequences at a particular locus from two individuals, you notice that an adenine (A) at position 513 in one species is a cytosine (C) in the other species, while all other bases in the gene sequence are the same. This is an example of what type(s) of mutation? Explain your answer.

Question 43

Before pre-mRNA is converted to mRNA, a process known as splicing occurs. At what point during the process of converting DNA into proteins does splicing occur?

Question 44

How do regulatory elements, such as enhancers, affect the expression of a gene in an organisms' phenotype?

Question 45

Explain what is meant when the genetic code is described as "degenerate."

Question 46

Based on the figure, what generalizations can we make about mutation rates across vastly different taxa?

Question 47

Which type of point mutation is most likely to have a deleterious effect on an organism's fitness: synonymous, nonsynonymous, or nonsense?

Question 48

Which type of point mutation occurs more frequently: transitions or transversions?

Question 49

Explain what is meant when we say that mutations occur randomly with respect to fitness.

Question 50

Joan Peris and her colleagues induced mutations in a virus called bacteriophage f1. What can be concluded from the distribution of observed fitness effects as a result of the mutations?