Introduction to Biology and Scientific Method

Nestor T. Hilvano, M.D., M.P.H.(Images Copyright Discover Biology, 5th ed., Singh-Cundy and Cain,

Textbook, 2012.)

Learning Objectives1. Define Biology and its subdivisions. 2. Discuss the process of science, discovery science and

scientific method (hypothesis-based science).3. List common properties of life. 4. Discuss levels of biological hierarchy (organization of life).5. Describe the web interactions in an ecosystem. 6. Describe evolution by means of natural selection7. Describe the 3 domains and the 4 kingdoms under domain

Eukarya.

Wordstems• ana – up ; cyto- cell • tom – to cut ; logy – to study• bio – life ; physio – nature • zoo - animal ; entomol – insect• gene – origin ; onto – being or

existing• molecul – a little mass • botan- pasture • micro- small • eco- house

Introduction• ______ What branch of science deals with the

study of life. (a. physiology b. biology c. botany d. zoology • Science is based on evidence that can be

demonstrated through observation and/or experiments

• Science is subject to independent validation and peer review

• Science can be challenged on the basis of evidence

• Science is self-correcting

How do we study life? Scientific Method

• Discovery science – making observations and measurements to develop conclusion (inductive reasoning)– Ex. All living things are made up of cells

• Hypothesis-based science – inquiry involves proposing and testing of hypothesis (deductive reasoning; hypothesis=educated guess); explanation for sets of observations; make predictions in ‘if-then’ statements; testable and falsifiable– Ex. Vertebrates have backbone, if human is a vertebrate, then

human has a backbone

Steps of Scientific Method1. Make Observations

2. Ask Questions – How? Why? When?

3. Make a Hypothesis (testable question); Predictions – use

deductive reasoning, “If … then” logic

4. Test of prediction – by carrying out experiments, using

control group and experimental group

5. Conclusion- accept or reject hypothesis• Variables: independent or manipulated variable (amount of toxin); dependent or responding variable (fish death)• Controlled experiment: -Control group: no change in independent variables (exposed to everything except toxin); -Experimental group: exposed to X amount of toxin (several levels in each group)

Scientific Theory

• A hypothesis becomes a scientific theory:

• After it has been repeatedly confirmed through diverse methods of testing

• When it is accepted by experts as the best explanation of the truth about the phenomenon  

Common Properties of Life1. Order- composed of

one or more cells

2. Regulation- maintain homeostasis

3. Growth and Development

4. Energy Utilization from their environment

5. Response to the Environment

6. Reproduction (using DNA)

7. Evolution (evolutionary adaptation)

http://www.nicerweb.com/bio1151/Locked/media/ch01/life.html

• Created through selective breeding, desired genetic characteristics were bred with each other until their descendants became distinctly different from the ancestor

Inferred from 2 observations:a)individual variationsb)overproduction and competition-inference: unequal reproductive success-the product of NS is (evolutionary) adaptation

Biological Hierarchy (Organization)1. Biosphere – all ecosystems that support life.

2. Ecosystem - relationship bet. living and nonliving. 3. Community – all organisms in an ecosystem. 4. Population - group of one species; evolution occur 5. Organism - an individual living thing; single cell to multicellular 6. Organ System - several organs that work together (ex. respiratory

system)7. Organ - made up of different tissues (ex. nasal cavity, pharynx,

trachea, bronchi, and lungs, )8. Tissue - group of similar cells (ex. epithelial, connective, muscular,

nervous tissues9. Cell – smallest (functional) unit of life (ex. nerve cell) 10.Organelle - structure within a cell (ex. ribosome, nucleus)11. Molecule - group of atoms (DNA) 12. Atom – smallest chemical unit (carbon, oxygen, hydrogen, nitrogen)

* 2 types of cells: Prokaryotes, Eukaryotes ___ -cell with nucleus ___ - cell without nucleus

•Old Kingdom System; Bacteria and Archaea (under Kingdom Monera)

Linnaeus Classification• Linnaeus devised seven division system and binomial

nomenclature • Kingdom, Phylum, Class, Order, Family, Genus, species• Importance: To provide a scientific name that is

accepted and communicated by scientists around the world, to show relationships between groups, and to identify organisms accurately

• binomial nomenclature: Genus species: always written capital Genus & lower case species; in italics when typed, underlined when hand written

Homework (Self Review) 1. Define the following: biology; cell; biosphere;

ecosystem, community, population; tissue; organ system; organ; independent variable; dependent variable; controlled group; experimental group; hypothesis; scientific theory, prokaryotes, and eukaryotes.

2. Describe the common properties of life.

3. List down Linnaeus taxonomy in descending order.

4. Describe Darwin’s theory of evolution based on natural selection.

5. What is artificial selection?

6. Classify the items listed below as to Kingdoms of life:

a) yeast b) rabbit c) mushroom

d) amoeba e) maple tree f) algae