If 20 beats are produced within one second which of the following frequencies could possibly be held by two sound waves traveling through a medium along a common pants at the same time? a. 18 hz and 26 hz b. 22 hz and 42 hz c. 38 hz and 63 hz d. 47 hz and 55 hz

How do antiviral drugs work? in your own words.

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?

4. multiple crosses were made between true-breeding lines of black and yellow labrador retrievers. all the f1 progeny were black. when these progeny were intercrossed, they produced an f2 consisting of 91 black, 39 yellow and 30 chocolate. a. propose an explanation for the inheritance of coat color in labradors. b. propose a biochemical pathway for coat color determination and indicate how the relevant genes control coat coloration.