Biology is the study of life, including the anatomy, physiology, growth, origin, evolution, distribution, and taxonomy of organisms. It examines life at the molecular, cellular, organism, and population levels. Key principles that unify modern biology are the cell theory, evolution, genetics, homeostasis, and the role of energy in living things.

1. NATURE OF LIFEBiology as the Study of Life

2. What is biology?Biology – the science that deals with all life forms including their:A. Anatomy – the branch of science that studies the physical structure of animals, plants, and other organisms.B. Physiology – the branch of biology that deals with the internal workings of living things such as:B.1. metabolism – the series of processes by which food is converted into energy and products needed to sustain life.B.2. respiration – the biochemical pathway which takes place in cells and results in the release of energy from organic molecules.C6H12O6 + 6O2 > 6H20 + 6CO2 + Energy B.3. reproduction – the production of offspring or new individuals through sexual or asexual process. Rather than with their shape or structure.

3. WHAT IS BIOLOGY?C. Growth – involves the addition of more body substance. It usually means that the organisms get larger. D. OriginE. Evolution - the theoretical process by which all species develop from earlier forms of life. According to this theory, natural variation in the genetic material of a population favors reproduction by some individuals more than others, so that over the generations all members of the population come to possess the favorable traits.F. DistributionG. Taxonomy - the science of classifying plants, animals, and microorganisms into increasingly broader categories based on shared features. Traditionally, organisms were grouped by physical resemblances, but in recent times other criteria such as genetic matching have also been used.

4. Etymology of biologyBiology was inspired by two Greek words.Bio – meaning life andLogia – meaning study of.Modern biology origins and its approach to the study of nature are most often traced back to ancient Greece.Aristotle (384 BC to 322 BC) contributed most extensively to the study of Biology.In his book “History of Animals” it was shown that he has naturalistic leanings.But he later showed more empirical works that focused on a. biological causation and b. diversity of life.Theophrastus (372 BC? to 287 BC) – he was Aristotle’s successor in Lyceum.Wrote a series of books on botany.It was the most important contribution of antiquity to the plant sciences.

5. WHO FIRST USED THE TERM BIOLOGY IN ITS MODERN SENSE? The term biology was introduced in Germany in the 1800’s.People who have independently introduced Biology in its modern sense are the following:Karl Friedrich Burdach(1800) Gottfried Reinhold Treviranus(1802) – wrote “Biologie oder Philosophie der lebenden Natur”Jean Baptiste de Lamarck (1800’s) – French naturalist who popularized the term biology. He used it to encompass the growing number of disciplines involved with the study of living things.Thomas Henry Huxley (1800’s) – English zoologist who greatly aroused interest on biology as a unifying concept for zoology and botany.

6. WHERE THERE EARLIER STUDIES RELATED TO BIOLOGY?Sciences related to and included within modern Biology have been studied since ancient times.One of which is Natural Philosophy.Natural Philosophy – the study of nature and natural phenomena.Ancient civilizations who are naturalists include:A. Mesopotamians (In modern times situated in Iraq and Syria)B. EgyptiansC. IndiansD. Chinese

7. EARLY SCIENTISTS WHO CONTRIBUTED IN THE DEVELOPMENT OF BIOLOGYAnton Van Leeuwenhoek (1632-1723) – with his dramatic improvement of the microscope, biology began to quickly develop.He observed the following things in his compound microscope.A. Red Blood CorpuscleB. Protozoa C. Bacteria and D. Spermatozoa in insects and humans. Mathias Jakob Schleiden (1804-1881) and Theodor Schwann (1810-1882) – presented the three tenets of cell theory.1. All organisms consists of one or more cells.2. Individual cells have all the characteristics of life or the cell is the basic unit of life .3. All cells come from the division of other cells or all cells arise from existing cells.

8. EARLY SCIENTISTS WHO CONTRIBUTED IN THE DEVELOPMENT OF BIOLOGY Taxonomy and classification became a focus in the study of natural history in the 18th century.Carolus Linnaeus (1707-1778) – He proposed a classification system for flowering plants. He wrote and published a book about it in “Systema Naturae” (1735). He presented his binomial classification system for plants and animals.He wrote and published a book about it in “Species Plantarum” (1735).E.g. Binomial classification – Solanum tuberosum – Irish potato

9. EARLY SCIENTISTS WHO CONTRIBUTED IN THE DEVELOPMENT OF BIOLOGY Jean Baptiste de Lamarck (1744-1829) – French botanist and zoologist– he formulated an early theory of evolution based on inherited characteristics.He published the essay 'Philosophie Zoologique' ('Zoological Philosophy')(1809), in which he suggests that characteristics developed during a creature's lifetime may be inherited. He compiled Histoire naturelle des animaux sans vertèbres (1815-1822) (Natural History of Animals without Backbones).Charles Robert Darwin (1809-1882) - British Naturalist who proposed theory of natural selection.Natural selection - the process, according to Darwin, by which organisms best suited to survival in their environment achieve greater reproductive success, thereby passing advantageous genetic characteristics on to future generations.Published the books “On the Origin of Species” (1859), “The Descent of Man and Selection in relation to Sex” (1871) and “The Expression of the Emotions in Man and Animals” (1872).

10. EARLY SCIENTISTS WHO CONTRIBUTED IN THE DEVELOPMENT OF BIOLOGY Alfred Wallace (1823-1913) – British naturalist who developed the theory of evolution contemporaneously with British naturalist Charles Darwin.He wrote and published the books “The Malay Archipelago”(1869), “Contributions to the Theory of Natural Selection”(1870) and “The Geographic Distribution of Animals”(1876).He sent a paper containing his theory of evolution to Charles Darwin, who arranged, through Charles Lyell, for it to be jointly read before the Linnaean Society with his own in 1858.

11. BIOLOGY IN RECENT TIMESOver the years the scope of biology has shifted.Biology today is subdivided into hierarchies based on:a. Molecule – smallest part of a chemical compound.b. Cell – basic unit of living things.c. Organism – Living things. (Unicellular or Multicellular)d. Population – Individuals of the same species.

12. BIOLOGY IN RECENT TIMESIn modern biology – molecular biology has made the most fundamental contributions.Molecular biology - the branch of biology concerned with the nature and function, at the molecular level, of biological phenomena such as RNA and DNA, proteins, and other macromolecules.Molecular biology spans a. biophysics and biochemistry.

13. FIVE UNIFYING PRINCIPLES OF MODERN BIOLOGY With the many studies of biology, these are the principles that unify them:1. Cell theory – cells are the basic unit of life.2. Evolution – new species and inherited traits are the product of evolution.3. Genetics – genes are the basic unit of heredity.4. Homeostasis – an organism that regulates its internal environment to maintain a stable and constant condition.

14. FIVE UNIFYING PRINCIPLES OF MODERN BIOLOGY 5. Energy – Living things consume andtransform energy.