Which best describes the pericardium?

a. structures inside the heart that ensure that blood flows in one direction only
b. a sac around the heart that allows the heart muscle to receive oxygen
c. a sac around the heart that protects the heart and chest tissues
d. structures inside the heart that bring blood to the lungs for oxygenation

Based on the observation that only male crickets produce a song, you hypothesize that a male's song is a form of communication to potential mates. you set up a simple experiment to test this hypothesis. in the laboratory, you place a male snowy tree cricket in enclosure a, which is adjacent to enclosureb. in enclosure b, you place other insects, one at a time, and observe their responses to the male's song. the enclosures are designed so that the two insects being tested cannot see or smell each other, but sound is transmitted from enclosure a to enclosureb.

Why is taking care of yourself a time management techique

There are multiple lines of evidence that provide support for common ancestry and evolution. write 3-4 paragraphs describing at least three of them in detail. provide at least one example for each line of evidence.