Define crossing over. in which stage does it occur?

M! (1). what are the inputs and the outputs for cellular respiration? (2). what is the primary source of energy for cellular respiration?

Which organisms have pharyngeal arches that develop from all three germ layers and go through the same development stages as embryos? 1.bird 2.ladybug 3.starfish 4.snake

When the cell concentrates potassium within, against the natural tendency of matter, it is performing a. passive diffusion b. facilitated diffusion c. active transport d. pinocytosis