Critical Thinking When a spherical cell increases in diameter from 2 um to 20 um, by what factor does its surface area change? By what factor does its volume change? (The surface area of a sphere
= 41 radius?, and the volume of a sphere = 4/31 radius'. Remember that diameter = 2 x radius.)

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?

Which of the following is a period in the paleozoic era? devonian cambrian permian all of the above

How does the fermentation of pyruvic acid in cells contribute to the formation of atp? a. it completes the oxidation of glucose to co2, creating atp. b. it generates lactic acid, which cycles back through the krebs cycle, producing 2 atp molecules. c. it converts fadh2 to phosphate, which bonds with adp. d. it produces 2 nad+ molecules, which cycle back to fuel the glycolysis reaction, allowing 2 atp molecules to be produced.