Deck 24: Genome Evolution

Question 1

Arabidopsis thaliana and the pufferfish (Fugu rubripes) are examples of _________________ organisms whose genomes have been sequenced.

Answer 1

model

Question 2

The protein-coding gene sequences in humans and chimpanzees

A)are vastly different.
B)are about 50% alike.
C)are about 80% alike.
D)are more than 99% alike.

Answer 2

D

Question 3

Genes that have DNA sequences similar to functional genes but that do not appear to produce any functional product are ________________.

Answer 3

pseudogenes

Question 4

Genes are found in the same order for large stretches of the X chromosome in the rat and mouse genomes, indicating

A)occurence of aneuploidy.
B)formation of pseudogenes.
C)conservation of synteny.
D)conservation of neoteny.

Question 5

One of the unexpected findings to occur in comparing mouse and human genomes is

A)that "junk" DNA may be more functional than we assumed.
B)how incredibly different they are.
C)that there is far more "junk" DNA than we ever thought.
D)how similar some gene families are to their original transposons.

Question 6

If a gene is found in different groups, it is said to be

A)active.
B)variable.
C)conserved.
D)associational.

Question 7

One of the reasons that pufferfish are a good species to compare to humans is because

A)it is so easy to hybridize the two and investigate the consequences.
B)they are so distantly related that it's easy to distinguish mutually conserved sequences.
C)the introns are often identical.
D)of the rapid response time in pufferfish to artificial selection.

Question 8

The best explanation for the phenotypic differences between humans and chimps despite the great similarities in their gene-coding sequences is

A)the vast differences in exons between their genomes.
B)the vast differences in the introns between their genomes.
C)the "junk" DNA of humans contains important sequences not present in chimps.
D)differences in gene expression between species.

Question 9

Two genes within an organism that arose from the duplication of a single gene in an ancestor are ________________.

Question 10

Genome sequencing of the parasitic protist Plasmodium falciparum has been completed.One of the results is

A)Plasmodium is highly genetically similar to its host, Anopheles.
B)Plasmodium is highly genetically similar to its host, Drosophila.
C)Plasmodium has a chloroplast-like apicoplast that could be targeted by drugs.
D)Plasmodium produces fatty acids that are similar to ones found in humans and could be targeted by drugs.

Question 11

The genomes of Arabidopsis thaliana, a small member of the mustard family of plants, and rice, Oryza sativa, have been sequenced.The findings include

A)the genome for each is almost identical, indicating that they diverged in the fairly recent past.
B)they each have very high copy numbers (slightly divergent copies of a gene), probably indicating episodes of polyploidy and/or segmental duplication.
C)repetitive DNA, including retrotransposons, was a very small proportion of both genomes.
D)more than 90% of the genes in each were particular to plants and not found in animal or fungal genomes.

Question 12

In plants, _________________ induces elimination of duplicated genes.

Question 13

Over long segments of chromosomes, the linear order of mouse and human genes is preserved.This is called conserved ______________.

Question 14

Many retroviral-like transposons found in the human genome may have been transferred from viruses to mammals via ______ gene transfer.

Question 15

Except in rare cases, genes are usually passed from generation to generation within a species.This process is called:

A)horizontal gene transfer
B)vertical gene transfer
C)transgenesis
D)synteny

Question 16

Choose the true statement about the human genome and the tiger pufferfish genomes.

A)Essentially all the human genes have nearly identical counterparts in pufferfish.
B)The order of genes along the chromosomes in both species is essentially identical.
C)Both species have about the same amount of introns and "nonsense" sequences of DNA.
D)About 25% of human genes are unique when compared to the tiger pufferfish genome.

Question 17

Using the sequencing results for genomes from each of the kingdoms, it is currently possible

A)to explore genetic differences between species very directly, examining DNA changes.
B)to build, from scratch, complex organisms with trans-kingdom genomes.
C)to sequence and build, from scratch, simple organisms with trans-kingdom genomes.
D)to design humans with a variety of inter-kingdom abilities built into their DNA.

Question 18

The entire DNA sequence of a species is called its ________________.

Question 19

The breast cancer gene BRCA1 has a very similar sequence in humans, mice, and gorillas, due to its origination in a common ancestor.The BRCA1 genes in these species are examples of __________________.

A)orthologs
B)paralogs
C)polyploidy
D)synteny

Question 20

One of the ways that two species can be compared, and information about the genetic basis of human diseases extracted, is by using their sequenced genomes and

A)looking at the allelic differences.
B)investigating the introns.
C)looking at the conserved sequences.
D)exchanging genomic information between them.

Question 21

Today, gene swapping between two species is

A)impossible, but it happened frequently in the distant past.
B)infrequent but possible; it happened more often in the distant past.
C)much more frequent compared to in the distant past.
D)only possible if they are in the same family of organisms, such as lions and tigers.

Question 22

What type of genes would be most likely to exhibit different expression patterns between humans and non-human primates, such as gorillas?

A)Genes controlling brain development.
B)Genes controlling mammary gland development.
C)Genes controlling lung development.
D)Genes controlling heart development.

Question 23

Plant species regularly hybridize in nature, but only some crosses result in new polyploid species.Of the crosses below, if each one occurred, which would be most likely to result in a new stable polyploid species?

A)A cross between a 2n gamete and a 1n gamete, forming a 3n hybrid.
B)A cross between a 4n gamete and a 1n gamete, forming a 5n hybrid.
C)A cross between a species with a CC genome and a species with a DD genome, forming a hybrid with a CD genome.
D)A cross between a species with a BB genome and a species with a DD genome, followed by a doubling of chromosomes, forming a hybrid with a BBDD genome.

Question 24

Choose the true statement about the role of polyploidization in the evolution of plant genomes.

A)Jumping of transposons is most common many generations after a polyploidization event.
B)Genome downsizing following allopolyploidy usually affects the participating hybrids equally.
C)Genome downsizing following allopolyploidy results mainly from duplicate gene loss.
D)Crop plants rarely show evidence of polyploidization events.

Question 25

Petrels (a flying and diving seabird) are thought to be one of the closest living relatives to penguins.What type of genes would be most likely to exhibit different expression patterns between these species?

A)Genes controlling skeletal development.
B)Genes regulating the digestive tract.
C)Genes regulating salt water tolerance.
D)Genes controlling organ development.

Question 26

Choose the most influential contributing factor to the reduced sense of smell in humans compared with the other great apes.

A)pseudogenes
B)conservation of synteny
C)aneuploidy
D)one more chromosome in humans compared to the other great apes

Question 27

Many genes in the human genome are no longer expressed because mutations have introduced stop codons within the coding sequence or transposons have disrupted gene function.These genes are now considered

A)pseudogenes.
B)orthologs.
C)paralogs.
D)homologues.

Question 28

The best explanation for why a mouse develops into a mouse and not a human is

A)most of the coding genes are different.
B)most of the non-coding genes are different.
C)gene expression differs.
D)the genes are mostly the same but have been rearranged.

Question 29

Choose the true statement about synteny.

A)Synteny refers to the conservation of gene order along chromosomes.
B)Synteny refers to the constancy of chromosome numbers in related clades.
C)Synteny results from polyploidization events.
D)Synteny refers to the rearrangement of gene order due to inversions.

Question 30

Crop sunflowers are attacked by many fungal pathogens, such as downy mildew and Sclerotinia, resulting in economic losses of millions of dollars per year.What genes would be best to target for the development of new fungus-killing crop treatments (fungicides)?

A)Genes encoding chitin proteins that are shared by downy mildew and Sclerotinia, but absent in sunflower and humans.
B)Genes encoding growth proteins that are shared by downy mildew, Sclerotinia, and sunflower, but absent in humans.
C)Genes encoding metabolite proteins that are shared by downy mildew, Sclerotinia, and humans, but absent in sunflower.
D)Genes encoding basic development proteins that are shared by downy mildew, Sclerotinia, sunflower, and humans.

Question 31

Gene inactivation is likely to produce

A)pseudogenes.
B) orthologs.
C) paralogs.
D)homologues.

Question 32

Some of the olfactory receptor (OR) genes in humans

A)have been inactivated, reducing our olfactory capabilities compared to other primates.
B)have been activated, enhancing our olfactory sense compared to other primates.
C)have duplicated more frequently, resulting in increased paralogs compared to other primates.
D) have been conserved more rigidly, resulting in increased orthologs compared to other primates.

Question 33

Choose the correct sequence of events involving allopolyploidy that gave rise to modern tobacco.

A)hybridization, chromosome doubling, duplicate gene loss
B)hybridization, duplicate gene loss, chromosome doubling
C)chromosome doubling, hybridization, duplicate gene loss
D)duplicate gene loss, hybridization, chromosome doubling

Question 34

Recent research has suggested that some pseudogenes and non-protein-coding DNA code for RNAs that affect transcription of coding regions.This suggests that

A)pseudogenes code for proteins.
B)non-protein-coding DNA has no function.
C)non-protein-coding DNA may regulate gene expression.
D)pseudogenes have no function.

Question 35

The best target for drug development would be

A)genes that are shared by humans and the organisms causing Chagas disease, African sleeping sickness, and Leishmania.
B)genes that are shared by the organisms causing Chagas disease and African sleeping sickness but not shared by humans or the organisms causing Leishmania.
C)genes that are shared by humans and the organisms causing Chagas disease but not the organisms causing African sleeping sickness or Leishmania.
D)genes that are shared by the organisms causing Chagas disease, African sleeping sickness, and Leishmania but not shared by humans.

Question 36

The human genome

A)has no foreign DNA because it is excised by DNase.
B)has a very small amount of foreign DNA, mostly in the end caps (telomeres) of chromosomes.
C)has a lot of foreign DNA, mostly in the end caps (telomeres) of chromosomes.
D)has a lot of foreign DNA scattered throughout the genome, including transposons.

Question 37

Choose the true statement about foreign DNA in the human genome.

A)Most of the foreign DNA in the human genome is ancient.
B)Most of the foreign DNA in the human genome is coding DNA.
C)Like the Drosophila genome, the human genome is constantly eliminating its foreign DNA.
D)New foreign DNA is regularly entering the human genome.

Question 38

Which one of the following statements about horizontal gene transfer is false?

A)Horizontal gene transfer is also called lateral gene transfer.
B)Horizontal gene transfer involves hitchhiking genes from other species.
C)Horizontal gene transfer was common early in life, but is absent today.
D)Gene swapping is evident in the human genome.

Question 39

During meiosis, a hexaploid hybrid spontaneously eliminates one set of chromosomes (eliminates 1n).What is the most likely result of this deletion?

A)The hybrid will no longer be able to reproduce.
B)The hybrid will be able to reproduce with one of the parental species.
C)The hybrid will no longer be polyploid.
D)The hybrid will be able to reproduce only by self-fertilization.

Question 40

Choose the true statement about genome size and gene number in animals.

A)There is a strong correlation between the number of genes and genome size.
B)Much of the extra DNA in humans is in the form of exons.
C)The pufferfish has a larger genome than humans and more genes.
D)Genome size differences depend to a large extent on the amount of retrotransposon DNA present.