Projections of population growth. World population estimates from 1800 to 2100, based on high, medium and low United Nations projections in 2015 and UN historical estimates for pre-1950 data.
Answers. Best Answer: Cell-to-Cell communication is absolutely essential for multicellular organisms. The billions of cells of a human or an oak tree must communicate in order to develop from a fertilized egg and then survive and reproduce in turn.Communication among cells is also important for many unicellular organisms that must locate food and find mates in order to sexually reproduce.he process by which a signal on a cell's surface is converted into a specific cellular response, a series of steps called a signal-transduction pathway, has been extensively studied in many types of cells.
Long-distance communication is by means of nerves and circulating hormones; the principal function of many organs, notably the endocrine glands, is to facilitate such communication between organs. Cells communicate with each other by means of an enormous diversity of signalling molecules.These molecules have traditionally been classified according to the distance over which they act. Local communication between neighbouring cells is described as paracrine signalling.ells communicate with each other by means of an enormous diversity of signalling molecules. These molecules have traditionally been classified according to the distance over which they act. Local communication between neighbouring cells is described as paracrine signalling.