In which of the following periods of the paleozoic era did the first vascular plants appear on land?
a. silurian
b. permian
c. cambrian
d. ordovician

In a relatively small iguana population the allelic frequency is tracked for three generations. webbing is a recessive allele; no webbing is the dominant allele. during one very rainy spring and summer, a flood washes all the iguana without webbed feet out to sea. by the fall, and three generations later, you have the gene pool seen here.

Which of the following describes a difference when gram-positive bacteria are compared to gram-negative bacteria?

During an experiment, readings for blood pressure in a persons body were found to be constant . however , when he measured by a different blood pressure cuff , the readings differed by 15 points for each reading. this difference indicates that the results are