Answer:
Nitrogen is in the soil under our feet, in the water we drink, and in the air we breathe. In fact, nitrogen is the most abundant element in Earth's atmosphere: approximately 78% of the atmosphere is nitrogen! Nitrogen is important to all living things, including us. Nitrogen is a naturally occurring element that is essential for growth and reproduction in both plants and animals. It is found in amino acids that make up proteins, in nucleic acids, that comprise the hereditary material and life's blueprint for all cells, and in many other organic and inorganic compounds.
Endosymbiotic theory is a theory of evolution that eukaryotes came from prokaryotes. Mitochondria and chloroplasts both have the double membranes. Each of them also contain genetic material that are replicated with a separate cell cycle. Both organelles have their own ribosomes.
Gizzard
Birds such as chicken, doves and others, and earthworms have gizzard which are responsible for storing and softening the consumed food in their digestive tract. The gizzard serves as the grinder of these food in preparation of the absorptive phase of the G.I tract.
Answer:
D. guard cells.. this is answer i think..