Sewall  Wright's  metaphor  of  evolution  on  an  adaptive  landscape describes a  population  as  occupying  a  field  of genotypes  graded  by  contours  delimiting  gene  combinations  of  equal  fitness.  The  evolutionary  mechanism  most likely to move a population consistently "uphill"  toward adaptive peaks on this landscape is

#Question id: 7163

#Unit 5. Developmental Biology

What statement is correct when comparing morphallaxis and epimorphosis?

#Question id: 7164

#Unit 5. Developmental Biology

If an amphibian zygote is manipulated so that the first cleavage plane fails to divide the gray crescent, then ________.

#Question id: 7165

#Unit 5. Developmental Biology

Embryonic induction, the influence of one group of cells on another group of cells, plays a critical role in embryonic development. In 1924, Hans Spemann and Hilde Mangold transplanted a piece of tissue that influences the formation of the notochord and neural tube, from the dorsal lip of an amphibian embryo to the ventral side of another amphibian embryo. If embryonic induction occurred, which of the following observations justifies the claim of embryonic induction?

#Question id: 7166

#Unit 5. Developmental Biology

Just prior to the onset of gastrulation in an embryo, the "organizer" cells are specified. If you were to experimentally block the specification of these cells, what would you expect the result to be in the developing embryo?

#Question id: 7167

#Unit 5. Developmental Biology

The following experiment is designed to study the role of several hormones in the regulation of metamorphosis in frogs.

These results suggest which of the following about prolactin (group 2 and group 7) at the dose tested?

#Question id: 7168

#Unit 5. Developmental Biology

Which one of the following signaling pathways will best support the mediolateral intercalation in the formation of the primitive streak in chick?