If viruses we somewhere else in the universe, they would be considered as living organisms because they would be living on their own and viruses cant survive out of a host cell, there are no hosts anywhere else in the universe only on earth because sustainace of life can only exists on earth
Growth hormones
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C. The cell took in another ancient prokaryotic cell, which began living inside it.
Answer:
E. are found in nitrogen-fixing cyanobacteria AND are used to protect nitrogenase.
Explanation:
Heterocysts are specialized cellular compartments found in nitrogen fixing cyanobacteria. They provide the ideal anaerobic environment for nitrogen fixation since nitrogenase enzyme cant work in presence of oxygen. Hence, in a cyanobacteria both the oxygen requiring photosynthesis process and the oxygen sensitive nitrogen fixation process takes place simultaneously.
Heterocysts have an additional cell wall made of glycolipid that provides a hydrophobic barrier to oxygen. They are involved in production of nitrogenase and other proteins that are required for nitrogen fixation. They also degrade photosystem II which is responsible for producing oxygen and produce proteins which remove any remaining oxygen.
The answer is B. Digestive and cardiovascular