Which of the following describes the structure of a dicot stem ? A) It contains a ring-shaped vascular bundle B) It contains central vascular cells C) It contains several layers of xylem that are surrounded by a ring of phloem D) It contains vascular bundles that scattered through the pith tissue

Which organelles are involved in energy conversion

Asmall number of finches are removed randomly from the wild and placed in a protected bird area. they are given as much food as they need and have plenty of space. why would natural selection not occur in this population? a. there is no reason for genetic mutation to occur. b. the birds compete for limited resources, c. the population has not reached carrying capacity. d. there is no genetic variation in the finches.

How can antibodies "remember" a particular bacterial invader or "antigen" on that invader?