Answer:
Explanation:
Remember, the 20 kinds of amino acids differ because of their R groups. These R groups also have different chemical bonding. There are R groups that form covalent bonds, some that form ionic bonds, and still others that form hydrogen bonds.
All cells require ATP for energy.
Answer:
Oxygen and carbon dioxide gases are exchanged through a network of tubes called tracheae. Instead of nostrils, insects breathe through openings in the thorax and abdomen called spiracles.
Explanation: