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TLS Online TPP Program

#Question id: 7260

There are maternally-determined variations along the animal-vegetal axis that are necessary for normal development in sea urchin. Which of the following statements about regulation in sea urchin embryos is consistent with that fact?

#Unit 5. Developmental Biology
  1. Up until the hatching of the embryo as a pluteus larva, any blastomere can be separated from the others and will regulate to go on and develop into a fully formed and full size larva.
  2. Up until the hatching of the embryo as a pluteus larva, any blastomere can be separated from the others and will regulate to go on and develop into a fully formed, yet smaller, larva.
  3. Blastomeres from the animal or vegetal poles of the embryo can be isolated and will go on to form an embryo, as long as either an animal or vegetal pole is included.
  4. Blastomeres at the 4-cell stage each still possesses a portion of the original animal-vegetal axis, and if isolated will go on to form a fully formed, yet smaller, larva.
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TLS Online TPP Program

#Question id: 5650

#Unit 5. Developmental Biology

Thalidomide, now banned for use as a sedative during pregnancy, was used in the early 1960s by many women in their first trimester of pregnancy. Some of these women gave birth to children with limb and organ deformities, suggesting that the drug most likely influenced ________.
TLS Online TPP Program

#Question id: 5651

#Unit 5. Developmental Biology

Growth and development of plant parts involves ________.

I) cell division to produce new cells

II) enlargement and elongation of cells

III) specialization of cells into tissues
TLS Online TPP Program

#Question id: 5652

#Unit 5. Developmental Biology

What generalization can be applied to the pole plasm of Drosophila, the P-granules of C. elegans, the yolk-free vegetal cytoplasm of Xenopus, and the localized mRNA for vasa in zebrafish?
TLS Online TPP Program

#Question id: 5653

#Unit 5. Developmental Biology

Why is meiosis required for germ cell formation, yet is never used by somatic cells?
TLS Online TPP Program

#Question id: 5654

#Unit 5. Developmental Biology

Two human disorders, Prader-Willi syndrome and Angelman syndrome, occur when a small deletion in a specific region of chromosome 15 is contributed by either the father or mother, respectively. Why does this small deletion not behave as a recessive allele for either syndrome, that is, why is its loss not made up for by the good copy of the region on chromosome 15 contributed by the other parent?
TLS Online TPP Program

#Question id: 5655

#Unit 5. Developmental Biology

What is the "acrosomal reaction"?