Changes

<p>Biology as a unified science was first developed in the nineteenth century, as scientists discovered that all living things shared certain fundamental characteristics and were best studied as a whole. Over a million papers are published annually in a wide array of biology and medicine journals,<sup class="reference" id="_ref-0">[1]</sup> and biology is a standard subject of instruction at schools and universities around the world.</p>

<p>As such a vast field, biology is divided into a number of disciplines. The old divisions by type of organism remains with subjects such as botany encompassing the study of plants, zoology with the study of animals, and microbiology as the study of microorganisms. The field may also be divided based on the scale at which it is studied: biochemistry examines the fundamental chemistry of life; cellular biology examines the basic building block of all life, the cell; Physiology examines the mechanical and physical functions of an organism; and ecology examines how various organisms interrelate. Applied fields of biology such as medicine are more complex and involve many specialized sub-disciplines.</p>

<h2><span class="mw-headline">Foundations of modern biology</span></h2>

<p>Biology is a branch of science that characterizes and investigates living organisms utilizing the scientific method. There are four broad unifying principles of biology:</p>

<li>Homeostasis. The physiological processes that allow an organism to maintain its internal environment notwithstanding its external environment. </li>

</ol>

<h3><span class="mw-headline">Cell Theory</span></h3>

<p>Cell theory states that all living things are composed of one or more cells as well as the secreted products of those cells, for example, plasma, extracellular matrix, and bone. These cells arise from other cells through cell division, and that in multicellular organisms, every cell in the organism's body has been produced from the single cell in a fertilized egg.</p>