Mammals have Toll-like receptors (TLRs) that act in a manner similar to those of insects. While not specific to a particular pathogen, a TLR can recognize a kind of macromolecule that is absent from vertebrates but present in/on certain groups of pathogens. Which of the following is most likely to be recognized by a particular TLR that defends against some viruses?

#Question id: 7096

#Unit 5. Developmental Biology

In which portion of the frog's life-cycle would a frog appear most similar to a mammal?

#Question id: 7097

#Unit 5. Developmental Biology

What property of the mammalian embryo permits the production of chimeric mice?

#Question id: 7098

#Unit 5. Developmental Biology

The role of maternal factors (such as Vg-1, Xwnt-1, and VegT) packaged into the vegetal region of the Xenopus oocyte is:

#Question id: 7099

#Unit 5. Developmental Biology

A fate map of a Xenopus blastula, just before gastrulation begins, shows that the top portion of the embryo will become ectoderm (skin and nerve), the central portion will become mesoderm (bone, muscle, and blood), and the lowest portion will become endoderm (gut). How is it that the endoderm and mesoderm, shown on the outside in the fate map, end up on the inside in the embryo after gastrulation?

#Question id: 7100

#Unit 5. Developmental Biology

If cells from the animal pole of a frog blastula (animal cap cells) are placed into contact with cells from the vegetal hemisphere, after removing the cells fated to form mesoderm, what is the result?

#Question id: 7101

#Unit 5. Developmental Biology

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