TLS Online TPP Program

#Question id: 14838


Sequence of amphibian lens induction postulated by experiments on embryos of the frog Xenopus laevis ; EXCEPT

#Unit 5. Developmental Biology
  1. Unidentified inducers (possibly from the foregut endoderm and cardiac mesoderm) cause the synthesis of the Otx2 transcription factor in the head ectoderm during the late neurula stage.
  2. As the neural folds rise, inducers from the anterior neural plate (including the region that will form the retina) induce Pax6 expression in the anterior ectoderm that can form lens tissue.
  3. As the neural folds rise, inducers from the anterior neural plate (including the region that will form the retina) induce Pax6 expression in the anterior ectoderm that can form lens tissue.
  4. The optic vesicle secretes BMP and FGF family paracrine factors, which induce the synthesis of the Sox transcription factors and initiate observable lens formation

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TLS Online TPP Program

#Question id: 4764

#Unit 8. Inheritance Biology

Which of the following is the best example of overdominance?

TLS Online TPP Program

#Question id: 4765

#Unit 8. Inheritance Biology

The recessive mutant allele that causes cystic fibrosis is much more frequent in Caucasians population than in other world populations. Some scientists believe heterozygotes must have had a survival advantage during plagues such as cholera that occasionally swept through this population. What concept does this illustrate?

TLS Online TPP Program

#Question id: 4766

#Unit 8. Inheritance Biology

In soybeans, resistance to sudden death syndrome (SDS) is inherited as a dominant condition. In some cases, individuals that are not resistant to SDS (but whose parents were) can pass the trait on to their progeny. This is an example of which of the following?

TLS Online TPP Program

#Question id: 4767

#Unit 8. Inheritance Biology

Neurofibromatosis is a condition in humans which is generally inherited in a dominant fashion. Assuming this disorder is 90% penetrant, what is the chance that a single child born to a father with neurofibromatosis and a mother known not to carry the mutation will have the disorder?

TLS Online TPP Program

#Question id: 4768

#Unit 8. Inheritance Biology

A trait that appears to be dominant in one sex but recessive in the other is called:

TLS Online TPP Program

#Question id: 4769

#Unit 8. Inheritance Biology

In some sheep, the presence of horns is produced by an autosomal allele that is dominant in males and recessive in females. A horned female is crossed with a hornless male. One of the resulting F1 females is crossed with a hornless male. What proportion of the male and female progeny from this cross will have horns?