Q37. Answer the questions for the following rhythm.   The r…

Q37. Answer the questions for the following rhythm.   The rhythm is [answer1]. The rate is [answer2]. Are there P waves present? [answer3] Are there R waves (QRS complex) present? [answer4] Is there a P wave to every QRS complex? [answer5] What is the length of the PR interval? [answer6]

The common ancestor of a clade of hummingbirds had a long, s…

The common ancestor of a clade of hummingbirds had a long, straight bill and most of its descendants share this trait (black circles).  However, two of its descendants possess short, curved bills (white circles).    What kind of trait is indicated by the white circles?