A regional thickening of cells at the anterior end of the primitive streak is termed____

a) Hensen’s node 

b) Primitive Knot

c) Primitive Groove

d) Primitive pit

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?