The four most abundant elements needed by the human body are carbon, hydrogen, oxygen, and nitrogen because these are needed in large amounts to support our cells, these are referred to as bulk elements.
Oxygen is the most essential element required by our body. The body requires oxygen in the form of gas which is inhaled by the air around us. All the cells in a human body require oxygen which is transported by the blood inside.
Cell is the most basic and fundamental unit of life. It can be of two types: prokaryotic and eukaryotic. Prokaryotic cell is the primitive one with no true nucleus and eukaryotic cell has a true nucleus and all the cell organelles. Generally eukaryotic cells require abundant amount of oxygen.
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Essentially, a control variable is what is kept the same throughout the experiment, and it is not of primary concern in the experimental outcome. Any change in a control variable in an experiment would invalidate the correlation of dependent variables (DV) to the independent variable (IV), thus skewing the results.
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They play an important role in the control system by sensing defects that occur during essential processes such as DNA replication or chromosome segregation, and inducing a cell cycle arrest in response until the defects are repaired.
