ch 24

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.

A

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 flight B. genes controlling diving C. genes controlling salt water tolerance D. genes controlling organ development

A

Canola (Brassica napus) is a product of a cross between B. rapa [2n = 20, (AA)] and B. oleracea [2n = 18, (CC)]. The genome of B. napus is A. 2n = 38 (AACC). B. 2n = 38 (AC). C. 2n = 19 (AACC). D. 2n = 19 (AC).

A

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

A

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 E. number of olfactory receptor (OR) genes present in the genome

A

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.

A

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. E. Synteny is only observed in closely related clades.

A

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.

A

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 sexually.

A

Gene inactivation is likely to produce A. pseudogenes. B. orthologues. C. paralogues. D. homologues. E. horizontal gene transfer (HGT).

A

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. orthologues. C. paralogues. D. homologues.

A

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.

C

Genes are found in the same order for large stretches of the X chromosome in the rat and mouse genomes, indicating A. regular aneuploidy. B. formation of pseudogenes. C. the conservation of synteny. D. the conservation of neoteny.

C

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.

D

Comparisons of human and mouse genomes reveals A. they have widely different numbers of genes, and share only a few more genes than humans and pufferfish. B. the differences between humans and mice are mainly the introns. C. they have very little in common. D. the genomes are very similar, with most of the genes unique to mice linked to size and shape. E. the genomes are very similar, with most of the genes unique to mice linked to smell and reproduction.

E

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 orthologues compared to other primates.

A

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.

A

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

A

A comparison of two newly sequenced genomes reveals that they differ by more nonsynonymous mutations than would be expected by chance. These results suggest that __________ selection is acting on these genomes. A. directional B. divergent C. stabilizing D. purifying

B

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. E. they have been separated for so many millions of years and yet the gene sequence is almost identical.

B

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.

B

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.

B

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.

C

If a gene is found in different groups, it is said to be A. active. B. variable. C. conserved. D. associational. E. endogenous.

C

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.

C

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. nonprotein-coding DNA has no function. C. nonprotein-coding DNA may function in the regulation of gene expression. D. pseudogenes have no function.

C

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. E. synteny has not been conserved.

C

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. E. The products of horizontal gene transfer often exist as transposons.

C

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.

D

Plant species regularly hybridize in nature, but only some crosses result in new polyploid species. Indicate the cross that would be most likely to result in a new polyploid species. A. A cross between a 1n species and a 2n species, forming a 3n hybrid. B. A cross between a 3n species and a 4n species, forming a 7n hybrid. C. A cross between a species with a CC genome and a species with a D genome, without a doubling of chromosomes, forming a hybrid with a CCD 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. E. Forces that increase genome size include polyploidy, proliferation of transposable elements, and gene duplication. D

D

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

D

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.

D

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.

D

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. E. are identical.

D