Genome Size
What is a genome?
A. The total number of chromosomes in a cell
B. The complete set of genetic material in an organism
C. Only the protein-coding genes of an organism
D. The physical appearance of an organism's chromosomes
B. The complete set of genetic material in an organism
What is coding DNA?
A. DNA sequences that encode proteins
B. DNA found only in bacteria
C. DNA that has lost all biological function
D. DNA located outside chromosomes
A. DNA sequences that encode proteins
What does polyploidy describe?
A. Having only one chromosome
B. Having more than two complete sets of chromosomes
C. Having a circular chromosome
D. Having chromosomes without DNA
B. Having more than two complete sets of chromosomes
What is the typical structure of the main chromosome in many prokaryotes?
A. Multiple linear chromosomes inside a nucleus
B. A single circular chromosome
C. A chromosome composed entirely of RNA
D. Several chromosomes enclosed in mitochondria
B. A single circular chromosome
Where is most of the genetic material of a typical eukaryotic cell located?
A. In the ribosomes
B. In the nucleus
C. In the cell membrane
D. In the cytoplasm outside organelles
B. In the nucleus
What is a karyotype?
A. A diagram showing relationships between different species
B. A measure of the total number of genes in a genome
C. A visual representation of an organism's chromosomes arranged by size and appearance
D. A sequence of DNA that can move within the genome
C. A visual representation of an organism's chromosomes arranged by size and appearance
What is a pseudogene?
A. A chromosome containing extra copies of every gene
B. A gene that can transfer between bacterial cells
C. A nonfunctional remnant of a formerly functional gene
D. A DNA sequence that always produces a protein
C. A nonfunctional remnant of a formerly functional gene
Which process can immediately increase the number of complete chromosome sets in an organism?
A. Whole-genome duplication
B. Descending dysploidy
C. Chromosome fusion without genome duplication
D. Loss of a plasmid
A. Whole-genome duplication
What is a plasmid?
A. A small DNA molecule separate from the main chromosome
B. A protein that packages DNA into chromosomes
C. A membrane surrounding bacterial DNA
D. A nonfunctional copy of a gene
A. A small DNA molecule separate from the main chromosome
How are nuclear chromosomes typically organized in eukaryotes?
A. As linear DNA molecules associated with proteins
B. As free-floating RNA molecules
C. As circular proteins without DNA
D. As independent ribosomes
A. As linear DNA molecules associated with proteins
Which statement best describes genome size variation?
A. All members of a biological kingdom have approximately the same genome size
B. Organisms with more complex bodies always have larger genomes
C. Genome size is determined entirely by the number of protein-coding genes
D. Genome size can vary dramatically between species without corresponding differences in complexity
D. Genome size can vary dramatically between species without corresponding differences in complexity
What is a transposable element?
A. A protein responsible for chromosome separation
B. A DNA sequence capable of moving or copying itself into different genomic locations
C. A chromosome that contains no genes
D. A type of RNA that carries amino acids
B. A DNA sequence capable of moving or copying itself into different genomic locations
What is descending dysploidy?
A. An increase in chromosome number caused by whole-genome duplication
B. The transfer of DNA between unrelated organisms
C. A reduction in chromosome number through rearrangements without necessarily losing genes
D. The destruction of all noncoding DNA
C. A reduction in chromosome number through rearrangements without necessarily losing genes
What is horizontal gene transfer?
A. The transfer of chromosomes from parent to offspring
B. The movement of DNA between organisms outside ordinary parent-to-offspring inheritance
C. The separation of chromosomes during cell division
D. The replication of DNA before mitosis
B. The movement of DNA between organisms outside ordinary parent-to-offspring inheritance
Which statement generally distinguishes eukaryotic genomes from prokaryotic genomes?
A. Eukaryotic genomes contain no noncoding DNA
B. Prokaryotic genomes always contain more chromosomes
C. Eukaryotic genomes often contain a greater proportion of noncoding DNA
D. Eukaryotic genomes cannot undergo duplication
C. Eukaryotic genomes often contain a greater proportion of noncoding DNA
A scientist compares genomes measuring 10 million and 10 billion base pairs. How many orders of magnitude separate them?
A. One
B. Two
C. Three
D. Four
C. Three
Which scientist discovered transposable elements through research on maize?
A. Rosalind Franklin
B. Barbara McClintock
C. Gregor Mendel
D. Thomas Hunt Morgan
B. Barbara McClintock
In the Machaerantherinae plant group discussed in the lecture, which evolutionary pattern was observed?
A. Polyploidy was more common in annuals than perennials
B. Descending dysploidy occurred approximately 11 times faster in annuals
C. Annuals and perennials always maintained identical chromosome numbers
D. Descending dysploidy occurred exclusively in perennials
B. Descending dysploidy occurred approximately 11 times faster in annuals
Which group contains mobile genetic elements found in prokaryotes?
A. Ribosomes, centrioles, and lysosomes
B. Telomeres, centromeres, and spindle fibers
C. Plasmids, transposons, and prophages
D. Chloroplasts, mitochondria, and nuclei
C. Plasmids, transposons, and prophages
In a haplodiploid system, which arrangement is common among bees, ants, and wasps?
A. Both males and females are haploid
B. Males are diploid and females are haploid
C. Both males and females are tetraploid
D. Males are haploid and females are diploid
D. Males are haploid and females are diploid
Why might natural selection favor a smaller genome in some organisms?
A. Smaller genomes always contain more functional genes
B. Smaller genomes eliminate the possibility of harmful mutations
C. Smaller genomes prevent horizontal gene transfer
D. Smaller genomes may require less time and energy to replicate
D. Smaller genomes may require less time and energy to replicate
How can transposable elements contribute to increasing genome size?
A. By converting all noncoding DNA into protein-coding DNA
B. By reducing the number of chromosomes through fusion
C. By copying themselves into additional locations within the genome
D. By preventing DNA replication
C. By copying themselves into additional locations within the genome
A plant lineage undergoes whole-genome duplication followed by chromosome fusions. Which outcome is possible?
A. The chromosome number can decrease after duplication while much of the duplicated genetic material remains
B. The lineage must lose all duplicated genes immediately
C. The chromosome number must continue increasing indefinitely
D. Chromosome fusions automatically return every gene to its original copy number
A. The chromosome number can decrease after duplication while much of the duplicated genetic material remains
Why can horizontal gene transfer complicate the reconstruction of evolutionary relationships?
A. It prevents mutations from occurring
B. It causes every organism to have the same genome
C. It eliminates the need for DNA replication
D. Genes can have evolutionary histories that differ from the lineages containing them
D. Genes can have evolutionary histories that differ from the lineages containing them
A diploid plant species has 2n = 14 chromosomes. If an individual undergoes whole-genome duplication and becomes tetraploid, how many chromosomes would it have?
A. 7
B. 14
C. 21
D. 28
D. 28