GST 123: Introduction to the Science of Biology

History and Philosophy of Science & Technology 

Image of the DNA helix structure 

Introduction to the Science of 'Biology' 

Biology is coined from two Greek words - 'bios' which means life and 'logos' which means study. We define biology as the 'study of life'. It is a broad field that covers cellular activities (workings taking place within the cells of living things), concepts of ecosystem and global climatic vicissitudes (changes). Persons who study intimate details of the human brain, the composition of our genes and even the functioning of our reproductive systems are known as 'biologists'. The following information below have been proven by biologists concerning cells: 

• all organisms consist of small cells which are too small to be seen by the naked eyes but large enough to be captured (seen) by an optical (light) microscope. 
• every cell is a complex system made up of certain building blocks which they called 'organelles' which are housed in a sac-like structure called a 'membrane bag'. 
• organisms exist either as 'unicellular' (i.e. single-celled) or 'multicellular' (many-celled). 
• the number of cells in the human body is estimated to be about 6x10³  and up to 320 different types of tissues. 
• a human red blood cell has a size (in diameter) of 0.005mm which is equivalent to 5 microns while some neurons are about 1m long. 
• human red blood cells live for 120 days which some other cells in the immune system of man last for a lifetime. 
• the diameters of animal and plant cells is about 10 - 100 microns. 
• trees, grasses, flowers, worms, cats, dogs and even humans are regarded as 'eukaryotes' while the bacteria is considered a 'prokaryote'. 
• viruses are not living organisms but they possess life when in a living host and therefore manifest features/qualities of living things. 

Image of a Bacteria cell & that of a Virus 

• optical microscopes cannot capture viruses, only an electron microscope can. 
• a 'prokaryotic cell' is a cell that lacks a membrane-bound nucleus and they possess a simple structure. But 'eukaryotic cells' has a nucleus that is membrane-bound. 
• Prokaryotes are unicellular organisms but Eukaryotes are multicellular. 
• The nucleus of an eukaryotic cell contains a necessary material called the 'chromosome' and this material or substance or part of the nucleus is chiefly responsible for the 'gene' of an organism because it carries the 'genetic material'. 

Eukaryotic cells possess some internal membrane compartments known as organelles. Some of these organelles include: 

• centrioles 
• lysosome 
• golgi apparatus 
• golgi bodies 
• mitochondria etc. 

The mitochondria in eukaryotic cells or organisms is responsible for respiration because it is specialized for energy production. The organelle found in plant cells responsible for the production of 'starch' by means of sunlight is known as  'the chloroplast'. Light as we know it, is the 'ultimate source of energy' for almost all things on earth. The following key points must be noted importantly: 

1. growth is an essential feature of most living cells apart from the ability to reproduce. 
2. the growth of a single cell and its splitting (division) is known as the 'cell cycle'. 
3. there are three major stages involved in the cell cycle - mitosis, cytokinesis and interphase. 
4. mitosis otherwise known as karyokinesis which is the phase at which the nucleus is actively dividing, while cytokinesis is the stage at which other cell contents are distributed into the progeny cells and interphase is the phase at the which the cell is not dividing/splitting. 

Branches of Biology 

Biology is divided into the following branches: 

• Zoology 
• Botany 
• Microbiology 
• Paleontology 

Zoology

This is the aspect/branch of biology that is concerned with the study of animal life and the invention of the microscope and the use of experimental techniques and methodologies expanded zoology as a field and brought about 'cytology' and 'histology' as branches of zoology. 

Botany

This can be defined as the 'study of plants' and the establishment of botany as a branch of biology began in the 4th century B.C. with Aristotle and his pupil - Theophrastus. They worked out certain descriptions and principles of various types of plants and their functions which remained the prototype for botanical observation for 1,000 years. Interest in botany spread to the U.S in the 16th and 17th century by means of 'colonization' and European conquest. Further inquiry, study and observations in the field of botany led to the accurate discovery of other sciences on 'taxonomy' and 'morphology'. Botany has equally expanded into areas like 'molecular biology', 'ethnobotany' (which is the study of the use of plants in pre-industrial societies). 

Paleontology

This is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch. It entails the study of 'fossils' to classify organisms and study their interactions with one another and their environments. Simply put, 'paleontology' is the study of the history of life on Earth as reflected or contained in the 'fossil record'. 

Fossils are the 'remains' or 'traces' of organisms (plants, animals, fungi, bacteria and other unicellular living things) that lived in the geological past and are preserved in the Earth's crust. 

There are three main branches of paleontology viz 

• Invertebrate Paleontology (the study of invertebrate animal fossils) 
• Vertebrate Paleontology (the study of vertebrate fossils from primitive fishes to mammals) 
• Human Paleontology also known as Paleoanthropology - the study of 'pre-historic human' and 'proto-human fossils'. 

The Methods of Scientific Investigation 

What is 'scientific method'? 

This is the process by which scientists, collectively, and over time, endeavour to construct an accurate representation of the world. Scientific method attempts to minimize the influence of bias or prejudice in the experimenter when testing our hypothesis or a theory. 

The stages of the Scientific Method 

There are four [4] stages involved in the scientific method: 

1. Observation and Description of a phenomenon or phenomena 
2. Formulation of an 'hypothesis' to explain the phenomena 
3. Use of the hypothesis to predict the existence of other phenomena or to quantitatively predict the results of new observations. 
4. Performance of experimental tests of the predictions by several independent experimenters and properly performed experiments. 

The Common Mistakes We Make in Applying the Scientific Method 

1. 'common sense'  and 'logic' because they tempt us into the belief that 'no test' is needed to prove a thing. This implies the absence of experimental tests to corroborate a hypothesis. 
2. to ignore or rule out data which do not support the hypothesis. 
3. failure to estimate quantitatively systematic errors. 

Please NOTE that: 'a scientific theory or law' represents a 'hypothesis' or 'a group of related hypotheses' which have been confirmed through repeated experimental tests. 

Likely Examination Questions

1. One of the 1st scientists to use a microscope to examine cells? 
2. Who arrived at the conclusion that plant tissues were made up of cells? 
3. Who arrived at a similar conclusion like the one above for 'animal cells'? 
4. Who propounded the theory or principle that 'cells come/came from pre-existing cells'? 
5. State the cell theory? 
6. "all organisms are composed of one or more cells and these cells arise from pre-existing cells", this statement is termed? 
7. Who concluded that 'fossils' were real and not 'inanimate' artefacts? 
8. Who is regarded as the 'father' of 'modern geology'? 
9. Who developed a theory known as the theory of 'uniformitarianism'? 
10. Who was the first person to attempt naming 'living organism'? 
11. Who is regarded as the 'father' of taxonomy? 
12. Taxonomy can also be called? 
13. Who developed the principle of 'biological succession'? 
14. Who proposed the theory of 'Natural Selection'? 
15. Humans have how many pair of chromosomes? 
16. Viruses can only replicate with the aid of ? 
17. the first 22 pairs of human chromosomes are referred to as? 
18. Some cells are short-lived for example the human red blood cell lives for ? 
19. All organisms require _______ for their metabolic reactions? 
20. Which of the following is not a characteristic of living things? 

• (a) Adaptation 
• (b) Heredity 
• (c) Reproduction 
• (d) None of the above