An amino acid is so named because its central carbon is linked to both an amino group and a

The breakdown of food is accomplished by enzymes. a. physical b. chemical c. mechanical d. none of the above

9. the history of life on earth is recorded in

Drag each tile to the correct box. the body monitors the levels of oxygen in the blood to regulate breathing. isabel is running in a marathon and is near the finish line. she feels out of breath. how will her nervous system work to generate a reaction? arrange the tiles in chronological order. isabel's breathing rate increases. sensory receptors in the arteries detect low oxygen levels. the brain sends signals through motor neurons. sensory neurons generate an impulse. the central nervous system relays an impulse to certain brain regions.