Mastering Biology CH 18 Practice Test

Although containing the same number of genes as the nematode genome, the human genome is thought to bear greater phenotypic diversity by means of _____.

All of the listed responses are correct.

NCBI provides _____.

All of the listed responses are correct.

The human genome is thought to contain about how many genes?

20,000-25,000

Given that about 25% of the mammalian genome is associated with genes, including introns and regulatory sequence, what would be the approximate average length of DNA per gene, if the genome contained 20,000 genes?

40,000 base pairs

What can be learned from comparing the genomes of distantly related species, such as yeast and humans, or plants and fruit flies?

Conserved genes provide insight into their evolutionary relationships.

What experimental approaches could be used to determine the function of this gene and its significance in human evolution?

Create knockout mice to determine their phenotype.

Why might a dog genome sequencing project prove particularly informative, compared to other mammalian genomes?

Genetic variation between breeds may be linked to phenotypic variation.

Why might active transposons be rare in natural populations?

Individuals with active transposons are usually eliminated by natural selection, because transposition events usually produce harmful mutations.

Why might the number of genes in the genome underestimate the number of different proteins that an organism makes?

Many genes undergo alternative splicing, so that different proteins with different exon combinations are produced from the same gene.

Who discovered "jumping genes" (transposons)?

McClintock

Which of the following best describes the findings of the ENCODE pilot study that thoroughly studied the makeup of a 1% region of the human genome?

Over 90% of the region was transcribed into different types of RNA.

Which of the following best describes the experimental evidence that the FOXP2 gene is vital to the normal development of vocalization in vertebrates and yet has evolved among different vertebrate lineages?

Replacing the FOX2P gene in mice with a humanized version of the gene had no negative effects on the mice but did lead to the development of brain cells in neural circuits that are associated with speech development in humans.

What factor accounts most for the difference in genome size between vertebrates and prokaryotes?

Vertebrates have more noncoding DNA sequences.

Alu elements _____.

are derived from or related to transposable elements

Chromosomal rearrangements may be important in evolution because _____.

chromosome rearrangements lead to gene duplication, thus generating a "spare" copy of the gene that is free to evolve and acquire a new function

An example of a systems biology experiment might be _____.

determining how insulin resistance affects transcription of thousands of other genes in the genome

Multigene families arise as a result of _____.

errors during DNA replication and recombination

The molecular data indicate that the globin gene family _____.

evolved from a common globin gene ancestor that gave rise to both alpha- and beta-globin genes, as well as myoglobin and plant leghemoglobin

A rapid way for natural evolution to alter a protein-coding gene so it encodes a protein with a different structure and function is _____.

exon duplication and exon shuffling

The highly conserved sequence element present within homeotic genes is called the _____.

homeobox

Segments of eukaryotic DNA that can move from one site to another in the genome by means of an RNA intermediate are called _____.

retrotransposons

Detailed comparison of the human and chimpanzee genomes has revealed that _____.

most differences are in the form of chromosomal rearrangements

The advantage of copy-number variants (CNVs) over SNPs in human genomic studies is that CNVs _____.

occupy much longer stretches of DNA than SNPs, and are likely to have greater phenotypic consequences

The similarity of the homeobox in many different kinds of organisms is evidence _____.

of the common ancestry of different life-forms

A group of scientists is attempting to sequence the Neanderthal genome with DNA extracted from Neanderthal bones. Information from this project might reveal _____.

what genetic differences may be responsible for the superior abilities of modern humans to communicate and make more sophisticated tools