Answer:
DNA is made up of molecules called nucleotides. Each nucleotide contains a phosphate group, a sugar group and a nitrogen base. The four types of nitrogen bases are adenine (A), thymine (T), guanine (G) and cytosine (C). The order of these bases is what determines DNA's instructions, or genetic code
Explanation:
Answer:
I think its D
Explanation:
because the mitochondria makes energy and the cell wall lets things in and out of it
The different barriers that you have to go through are the different organs of the immune system. These are the lymphoid organs, thymus, and bone marrow. The secondary wall that you have to go through are the lymphatic tissues which include the lymph nodes, adenoids, skin, liver, tonsils, spleen, and the lymph vessels.
At all times, these systems work hand-in-hand so that the body can protect itself in order for it to survive
C) are capable of living independently.
Organelles are NOT capable of living in their own. Cells are the smallest units of life.
