Sodium is an element. What is the question?
Explanation:
The cell nucleus is a membrane-bound structure that contains a cell's hereditary information and controls its growth and reproduction. The main function of the cell nucleus is to control gene expression and mnedite the replication of DNA during the cell cycle.
That would be the chloroplasts. They are small cells in a leaf that store chlorophyll.
The answer that will complete the sentence is lack of
eutrophication. It is because eutrophication is considered to be important for
marine animals as this provides the bodies of water nutrients in which the
marine animals need and if they are lacking, the species composition may
change, the coral reefs may be destroyed, the oxygen that are dissolved are at
low level and what is more serious, dead zones can be formed in which the
ecosystem in the marine life may be destroyed or collapse.
I believe it's number 4 because similar to when wrong blood types are transfused into a body, the immune system will see the donated organ as a foreign object and attack it to protect the organism (human).
