The yeast S. cerevisiae exists in three forms: two haploid cells of different mating types—a and alpha and the diploid formed when an a and an a cell mate and fuse. The a cell and the a cell each encodes cell-type-specific regulators: a cells make the regulatory protein a1, and alpha cells make the proteins alpha1 and alpha2. A fourth regulatory protein, called Mcm1, is also involved in regulating the mating-type-specific genes (and many other genes) and is present in both cell types which shows Combinatorial Control.

The arrangement of regulators at the promoters of a-specific genes and a-specific genes is

cell type:	gene regulatory proteins:	target genes:
1.a cell (haploid)	a1 Mcm1	aSG alphaSG
2.αlpha cell (haploid)	alpha 1 alpha 2 Mcm2	hSG
3.a/αlpha cell (diploid)	a1 Mcm2 alpha2

TLS Online TPP Program

#Question id: 8895

#Unit 9. Diversity of Life Forms

What is one characteristic that separates chordates from all other animals?

TLS Online TPP Program

#Question id: 8896

#Unit 9. Diversity of Life Forms

Chordate pharyngeal slits appear to have functioned first as

TLS Online TPP Program

#Question id: 8897

#Unit 9. Diversity of Life Forms

Which of the following statements would be least acceptable to most zoologists?

TLS Online TPP Program

#Question id: 8898

#Unit 9. Diversity of Life Forms

Which extant chordates are postulated to be most like the earliest chordates in appearance?

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.