A biologist began studying a population of bullfrogs. In 1998, she found that
most of the male frogs croaked, but some did not. A bat species known to
prey on male frogs migrated to the area in 2005. The biologist returned to the
area in 2008 and repeated population counts of male frogs. The table shows her data.

Ivan is looking at a cross section of a stem taken from a vascular plant. he sees two different types of vascular tissue: the xylem, which is closer to the center of the stem, and the phloem, located around the xylem, closer to the outside of the stem. how do these two structures work together in a living plant?

Speed is the ratio of the distance of an object moves to

In order to study genetic mutations, scientists must study genetic material. which statement describes the genetic material scientists are most likely studying? a) they study alleles that contain chromosomes, which are rna. b) they study alleles that contain genes, which are chromosomes. c) they study chromosomes that contain genes, which are dna segments.