After all this info you have given me, the correct one is Keystone species. As defined in sources like National Geographic, <span> These are types of plants or animals that play a unique and crucial role in the way an ecosystem functions. Without </span>keystone species<span>, the ecosystem would be dramatically different or cease to exist altogether. I hope this helps you a lot </span>
Answer: a. Aerobic respiration, b. Anaerobic respiration.
Explanation: Oxygen is an essential component for aerobic respiration because it is at the end of the electron transport chain, where it accepts electrons and picks up protons to give out water.
The final acceptor of electrons in the electron transport chain during aerobic respiration is oxygen.
The final electron acceptor in the Anaerobic respiration are inorganic molecules such as sulfates. Inorganic molecules are used rather than Oxygen.
Oxygen
<span>DNA (deoxyribonucleic acid). The DNA makes up genes, and the genes make up chromosomes.</span>