Answer:
The nucleus, cell membrane and cytoplasm.
Explanation:
The nucleus, cell membrane and cytoplasm are three elements that cannot be absent in a cell because they are necessary for the survival of the cell. The nucleus controls and regulates the activities happening inside the cell e.g. growth and metabolism etc. Cell membrane acts as a wall to protect the inner part of the cell from the external environment as well as allows nutrients and gases inside and outside the cell. Cytoplasm serves as a medium for the conduction of nutrients and waste from on place to another and also for the medium for organelles in which they floats.
The embedded proteins <u>allow specific substances to flow into the cell</u>.The phospholipid bilayer forms a stable barrier between two aqueous compartment.They embedded proteins carry the selective transportation of molecules and ensure their is cell to cell recognition.
The<em> cell membrane</em> controls the movement of substances in and out of cells and organelles. In this way, it is selectively permeable to ions and organic molecules.
Humans, when exhaling release carbon which helps them to make sugar, and as a biproduct plants release oxegen which humans inhale.
Mutations<span> are changes in the DNA. A single </span>mutation<span> can have a large effect, but in many cases, change is based on the accumulation of many </span>mutations<span>. Gene flow is any movement of genes from one population to another and is an important source of the genetic </span>variation<span>.</span>
