How do scientists determine where an earthquake starts

The current thought on the structure of the cell membrane is: a. a static phosphate sandwich of lipids b. a fluid-mosaic of phospholipids and proteins c. a bilayer of proteins with static lipid molecules d. an impermeable bilayer of protein molecules e. a static and permeable phospholipid single layer

Use the distance formula to determine weather each pair of segments have the same length

Why has two different alleles for the same trait?