During gastrulation, invagination occurs at the
A) archenteron.
B) blastocoel.
C) endometrium.
D) blastopore.
E) trophoblast
Answer: D) blastopore.
You might also like to view...
Pre-eclampsia is a pregnancy complication that is often explained as resulting from parent-offspring conflict. What underlies this conflict?
A. The fetus rejects excess resources to assist its siblings. B. The mother wants to provide the fetus with plenty of resources. C. The fetus demands more resources from the mother than would be optimal for her. D. Women gain more fitness (number of descendants) from earlier pregnancies than from later ones. E. Single pregnancies are much more common than multiple pregnancies (i.e., twins).
In reviewing historical records and ice core data, researchers noted that atmospheric CO2 levels started to rise as humans began to burn fossil fuels. This is an example of what type of relationship?
A. correlation B. symbioses C. causation D. antagonism E. conduction
The normal gene for hemoglobin was isolated, cloned, and subjected to restriction enzyme digestion with BamHI. Following gel electrophoresis, three bands are routinely obtained. However, following the same procedure with the hemoglobin gene from an individual with sickle-cell anemia, four bands are routinely obtained. These data suggest that
A) the mutation associated with sickle-cell anemia results in DNA that breaks easily. B) the mutation associated with sickle-cell anemia results in the loss of a BamHI cut site. C) the mutation associated with sickle-cell anemia results in several new enzyme cut sites for a variety of restriction enzymes. D) the mutation associated with sickle-cell anemia results in the gain of a BamHI cut site. E) the assay was not performed correctly.
Most density-dependent factors show negative feedback relative to population size. Which one of the following is more likely to show positive feedback relative to population size?
A. competition in small populations B. competition in large populations C. fecundity in small populations D. fecundity in large populations E. mortality in large populations