TLS Online TPP Program

#Question id: 2919


Topoisomerases play the essential role of unlinking the DNA molecules to allow them to separate into the two daughter cells for cell division. Which of the following statements regarding the mechanism of topoisomerases is INCORRECT?

#Unit 2. Cellular Organization
  1. Melting of the DNA strands is favored in highly negatively supercoiled DNA making this DNA an excellent substrate for relaxation.

  2. This product DNA is identical to the starting DNA molecule, except that the linking number has been increased by 1.

  3. Topoisomerase function requires that DNA cleavage, strand passage, and DNA rejoining all occur in a highly coordinated manner.

  4. The OH group from one broken DNA end attacks the phospho-tyrosine bond re-forming the DNA phosphodiester bond via ATP hydrolysis.

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TLS Online TPP Program

#Question id: 7273

#Unit 5. Developmental Biology

Hox9 and Hox10 paralogues specify the stylopod, Hox11 paralogues specify the zeugopod, and Hox12 and Hox13 paralogues specify the autopod. This scenario has been confirmed by numerous experiments.

Which of the following experiment correctly describe this scenario?

TLS Online TPP Program

#Question id: 7274

#Unit 5. Developmental Biology

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

 If the thyroid gland were removed from the tadpoles in Group 3, metamorphosis would

TLS Online TPP Program

#Question id: 7275

#Unit 5. Developmental Biology

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

 

If the thyroid gland were removed from the tadpoles in Group 4, metamorphosis would

TLS Online TPP Program

#Question id: 7276

#Unit 5. Developmental Biology

The cells that make up a tetrapod limb arise from three developing tissues:

The ____a______ will provide skeletal precursors to the limb.

The _____b____ will provide muscle precursors to the limb.

The _____c____ will provide the skin of the limb.

Which of the following option is correct?

TLS Online TPP Program

#Question id: 7277

#Unit 5. Developmental Biology

According to this model, Which of the following statements are correct?

TLS Online TPP Program

#Question id: 7278

#Unit 5. Developmental Biology

The following demonstrates the blastocoel formation in the mammals. Which of the following statement is correct?