Wild type E. coli metabolizes the sugar lactose by expressing the enzyme ß-galactosidase. You have isolated a mutant that you call lac1–, which cannot synthesize ß-galactosidase and cannot grow on lactose (Lac–). During an condition Lac– strain, called lac3–, is linked to the Tn5 insertion. From a strain carrying the Tn5 insertion and lac3– mutation you isolate an F’ that caries a region of the chromosome that includes both Tn5 and the linked Lac region. Introduce this F’ into an F– strain carrying lac1– by selecting for Kanr. These merodiploids express ß-galactosidase normally. If the merodiploid were Lac–, 

a) the two mutations lie in the different gene.

b) Both mutation are complement each other

c) the two mutations lie in the same gene.

d) Both of the mutations is dominant to wild type.

what could you conclude about the relationship between the lac3– and lac1– mutations from  these statements?

TLS Online TPP Program

#Question id: 8899

#Unit 9. Diversity of Life Forms

A new species of aquatic chordate is discovered that closely resembles an ancient form. It has the following characteristics: external armor of bony plates, no paired lateral fins, and a suspension-feeding mode of nutrition. In addition to these, it will probably have which of the following characteristics?

TLS Online TPP Program

#Question id: 8900

#Unit 9. Diversity of Life Forms

Which of the following statements about craniates is (are) correct?

1. Craniates are more highly cephalized than are non-craniates.

2. Craniatesʹ genomic evolution includes duplication of clusters of genes that code for transcription factors.

3. The craniate clade is synonymous with the vertebrate clade.

4. Pharyngeal slits that can assist in gas exchange originated in craniates,

5. The two-chambered heart originated with the early craniates.

TLS Online TPP Program

#Question id: 8901

#Unit 9. Diversity of Life Forms

The origin of the craniates occurred at roughly the same time as the

TLS Online TPP Program

#Question id: 8902

#Unit 9. Diversity of Life Forms

What do craniates have that earlier chordates did not have?

TLS Online TPP Program

#Question id: 8903

#Unit 9. Diversity of Life Forms

Terry detaches the snakelike organism from the fish and uses a knife to cut off its head. In doing so, its brain slides out onto the deck of the boat. Terry peers into the cut end of the head and notices that the brain had lain in a sort of pan-like structure that only partially surrounded the brain. What is the structure Terry is observing, and what is it made of?

TLS Online TPP Program

#Question id: 8904

#Unit 9. Diversity of Life Forms

Terry takes the body of the snakelike organism and slices it open along its dorsal side. If it is a hagfish, what should Terry see?