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TLS Online TPP Program

#Question id: 7101

What is the mechanism by which cells fated to be mesoderm form in the marginal zone of the Xenopus embryo?

#Unit 5. Developmental Biology
  1. Cells in the marginal zone are fated to be mesoderm, but they do not become specified or determined as mesoderm until after they move internally during gastrulation.
  2. Cells of the vegetal region are induced by their proximity to the animal region cells to become mesoderm.
  3. Maternal factors packaged into the marginal zone act on these cells to instruct them to become mesoderm.
  4. Secreted signals of the TGF- family are released by the cells of the vegetal region and act on the adjacent cells of the marginal zone to instruct them to adopt a mesodermal fate.
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TLS Online TPP Program

#Question id: 2774

#Unit 2. Cellular Organization

The DNA and protein sequences of the -tubulin genes in humans and in fish are similar, and because each arose due to speciation, these genes would be considered:
TLS Online TPP Program

#Question id: 19874

#Unit 13. Methods in Biology

Adding homopolymer tails to the 3’ end of DNA by an enzyme such as
TLS Online TPP Program

#Question id: 12956

#Unit 10. Ecological Principles

For  nearly 200  years, biogeographers have  noted that  the  tropics  have  more terrestrial species than  temperate regions. Which of the following is NOT a plausible explanation for this pattern?
TLS Online TPP Program

#Question id: 1478

#Unit 4. Cell Communication and Cell Signaling

Caspases are different on the basis of:
TLS Online TPP Program

#Question id: 5469

#Unit 8. Inheritance Biology

Breeding experiment was performed on pure lines of tomatoes differing in fruit weight. The plants were all grown in a controlled environment chamber providing equal environmental conditions for all individuals as far as humanly possible. The results were as follows:

a) One dominants polygene contribution?

b) What will be frequency of 20 g in F2 CLASSES?

c) Number of polygene loci for this character.