Which of the following series of events represents the path of vertebrate development?
|A)||formation of blastula, cleavage, neurulation, cell migration, gastrulation, organogenesis, growth|
|B)||formation of blastula, cleavage, gastrulation, neurulation, cell migration, organogenesis, growth|
|C)||cleavage, formation of blastula, gastrulation, neurulation, cell migration, organogenesis, growth|
|D)||cleavage, gastrulation, formation of blastula, neurulation, cell migration, organogenesis, growth|
Which of the following statements about Drosophila development is FALSE?
|A)||Drosophila go through four larval instar stages before undergoing metamorphosis.|
|B)||During the syncytial blastoderm stage, nuclei line up along the surface of the egg.|
|C)||Imaginal discs are groups of cells set aside that will give rise to key parts of the adult fly.|
|D)||Maternal, rather than zygotic, genes govern early Drosophila development.|
If a plant embryo failed to form enough ground tissue, what function(s) would likely be directly affected in the corresponding mature plant?
|D)||food and water storage|
C. elegans is a powerful developmental model because
|A)||these nematodes are very small, so it is easy to maintain a large population in a laboratory.|
|B)||the fate of every cell has been mapped.|
|C)||the fate of cells that will become eggs and sperm are predetermined.|
|D)||these nematodes have the same amount of DNA as Drosophila.|
Which of the following best describes a morphogen?
|A)||a cell that secretes diffusible signaling molecules that play a role in specifying cell fate|
|B)||a diffusible signaling molecule that plays a role in specifying cell fate|
|C)||a protein that helps mediate direct cell-cell interaction|
|D)||a protein that enables cells to become totipotent|
What would happen as a result of a transplantation experiment in a chick embryo in which cells determined to become a forelimb were replaced by some cells determined to become a hindlimb?
|A)||A hindlimb would form in the region where the forelimb should be.|
|B)||A forelimb would form in the region where the hindlimb should be.|
|C)||Nothing; the forelimb would form normally.|
|D)||Neither a forelimb nor a hindlimb would form because the cells were already determined.|
Which group of genes, identified by Nusslein-Volhard and Caroll, is responsible for the final stages of segmentation in Drosophila embryos?
|A)||morphogen gradient genes|
Suppose that during a mutagenesis screen to isolate mutations in Drosophila, you came across a fly with legs growing out of its head. What gene cluster is likely affected?
What would be the likely result of a mutation of the bcl-2 gene on the level of apoptosis?
|B)||a decrease in apoptosis|
|C)||an increase in apoptosis|
|D)||First it would increase, but later it would decrease.|
The gene clock hypothesis is best described by which of the following explanations?
|A)||Mutations accumulate partially through the addition of an -OH group to the base guanine.|
|B)||Specific genes exist to promote longevity.|
|C)||Free radicals can cause genetic mutations, particularly when we are sleeping.|
|D)||Calorie restriction leads to an increased life span.|