Giardia intestinalis can cause disease in several different mammalian species, including humans. Giardia organisms (G. intestinalis) that infect humans are similar morphologically to those that infect other mammals, thus they have been considered a single species. However, G. intestinalis has been divided into different subgroups based on their host and a few other characteristics. In 1999, a DNA sequence comparison study tested the hypothesis that these subgroups actually constitute different species. The following phylogenetic tree was constructed from the sequence comparison of rRNA from several subgroups of G. intestinalis and a few other morphologically distinct species of Giardia. The researchers concluded that the subgroups of Giardia are sufficiently different from one another genetically that they could be considered different species

By examining the phylogenetic tree diagrammed in the figure above, what conclusion can you draw about the species G. microti?

#Question id: 2822

#Unit 2. Cellular Organization

Transposition by a bacterial insertion element

a. occurs at a frequency of approximately 1 in 10^3 cells per generation.

b. can inactivate an essential gene.    

c. is mediated through a RNA intermediate.

d. requires the enzyme transposase

#Question id: 2823

#Unit 2. Cellular Organization

Transposition by a retrotransposon requires activity of which of the following enzymes?

a. RNA polymerase                b. reverse transcriptase

c. DNA methylase                  d. DNA polymerase

#Question id: 2824

#Unit 2. Cellular Organization

Plant mitochondrial DNA

a. is the same size as human mitochondrial DNA.

b. encodes a 5S mitochondrial rRNA.

c. contains multiple copies that recombine with each other.

d. uses the standard genetic code.

#Question id: 2825

#Unit 2. Cellular Organization

Metaphase chromosomes can be identified

a. by shape.                 

b. by the size and number of introns.

c. by banding patterns with Giemsa reagent.

d. by chromosome painting.

#Question id: 2826

#Unit 2. Cellular Organization

An open reading frame (ORF) is defined as a DNA sequence that

a. begins with a start codon.               

b. ends with a stop codon.

c. contains 50 codons.   

d. contains approximately an equal frequency of A, T, G, and C.

#Question id: 2827

#Unit 2. Cellular Organization

Two related genes that are derived from a gene duplication event are considered to be

a. homologous.                                   

b. paralogous.

c. orthologous.                       

d. members of a gene family.