The following experiment is designed to study the role of several hormones in the regulation of metamorphosis in frogs.

Group #	Treatment	Days to Metamorphosis
1	Saline	30
2	Prolactin	> 100
3	TSH	15
4	Thyroxine	10
5	Corticosterone	30
6	Thyroxine + Corticosterone	5
7	Prolactin + TSH	30
8	Thyroid gland removed	> 100

These results suggest which of the following about prolactin (group 2 and group 7) at the dose tested?

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#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?

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#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?

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#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.

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#Question id: 8901

#Unit 9. Diversity of Life Forms

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

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#Question id: 8902

#Unit 9. Diversity of Life Forms

What do craniates have that earlier chordates did not have?