Lecture -1 (C)Introduction to BiologyXI

Dr.Qurrat-ul-AinLecturer Biology

AKUEB-MSB3 Aug 2016

Objectives•Compare deductive and inductive

reasoning•Recall hypothesis, theory and scientific

law

Biological method•Observation•Hypothesis•Experiment•Data Collection•Conclusion•Retest

Observations:•The biologist recalls his/her previous

observations or makes new ones. Observations are made with five senses of vision, hearing, smell, taste and touch.

Observations

•An example of an observation might be noticing that people living in

villages are more tough and strong.

•Kinds of Observations: Observations may be of two types:▫Qualitative observations: Qualitative

observations are considered less accurate then quantitative ones because the qualitative observations are variable and non-measurable and cannot be recorded in terms of number.For example: The freezing point of water is colder than the boiling. One liter of water is heavier than one liter of ethanol.

• Quantitative observations: Quantitative observations are considered more accurate then qualitative ones because the quantitative observations are invariable and measurable and can be recorded in terms of number.For example: The freezing point of water is 0°C and the boiling point is 100°C.The mass of one litre water is 1000 grams while the mass of one litreethanol is 789 grams.

•An intelligent guess

•Biologist organizes his/her and others observations into data form and constructs a statement.

•This tentative explanation of the observations is called a hypothesis.

.

Hypothesis•An example of a

hypothesis might be that the village people are tough because they do more physical work.

Formulating a hypothesis•Reasoning: A great deal of careful and

creative thinking is necessary for the construction of a hypothesis. Biologists use reasoning to formulate a hypothesis.

•Deductive reasoning•Inductive reasoning

Deductive reasoning•The biologist draws deduction from the

hypothesis.•This involves the use of “if-then” logic.•It moves from general to specific.

•The classic exampleAll men are mortal. (major premise)Socrates is a man. (minor premise)Therefore, Socrates is mortal. (conclusion)

Deductive ReasoningExamples:1. All students eat pizza.

Claire is a student at ASU.Therefore, Claire eats pizza.

2. All athletes work out in the gym. Barry Bonds is an athlete. Therefore, Barry Bonds works out in the

gym.

Inductive reasoning•It moves from specific to general.•Example:•This marble from the bag is black. That

marble from the bag is black. A third marble from the bag is black. Therefore all the marbles in the bag black.

Other ways for hypothesis formulation•Intuition or imagination•Esthetic preferences•Religious or philosophical idea•Comparison and analogy•Discovery

Observation

Hypothesis formulation

(deductive/inductive)

Hypothesis testingTheory

Productive theory

Theory testing

Scientific law

Theory and productive theory•Theory : an hypothesis that is repeatedly

tested without ever being falsified.

•Productive theory: a theory that is predictive and has explanatory power.

•Suggests new and different hypothesis.

Scientific law•A scientific law is a uniform or constant

fact of nature, it is virtually an irrefutable theory. Biology is short in laws due to elusive nature of life