This document discusses the scientific method used in biology. It begins by outlining the steps of the scientific method: observation, hypothesis, experiment, data collection, conclusion, and retesting. It then goes into more detail about observations, distinguishing between qualitative and quantitative observations. It explains how hypotheses are formulated through reasoning, specifically deductive and inductive reasoning. The document also discusses the differences between hypotheses, theories, productive theories, and scientific laws.

1. Lecture -1 (C)
Introduction to Biology
XI
Dr.Qurrat-ul-Ain
Lecturer Biology
AKUEB-MSB
3 Aug 2016

2. Objectives
• Compare deductive and inductive reasoning
• Recall hypothesis, theory and scientific law

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

5. 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.

6. Observations
• An example of an
observation might be
noticing that people
living in villages are
more tough and
strong.

8. • 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.

9. • 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.

11. • An intelligent guess

12. • Biologist organizes
his/her and others
observations into data
form and constructs a
statement.
• This tentative
explanation of the
observations is called a
hypothesis.
.

13. Hypothesis
• An example of a
hypothesis might be
that the village
people are tough
because they do
more physical work.

14. 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

15. Deductive reasoning
• The biologist draws deduction from the
hypothesis.
• This involves the use of “if-then” logic.
• It moves from general to specific.

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

17. Deductive Reasoning
Examples:
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.

18. 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.

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

23. Observation
Hypothesis
formulation
(deductive/inductive)
Hypothesis testing
TheoryProductive theoryTheory testing
Scientific law

24. 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.

25. 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