CHAPTER 1The Nature of Science and the

Characteristics of Life

This Class is about You…

• This class is about us and how we connect with other living beings and our surroundings

• Many controversies facing society today require an understanding of science to make informed decisions– What are some examples of these controversies?

What is Biology?

• Biology is the scientific study of life– What does Bio mean?– What does –ology mean?

The Language of Science

• Challenging vocabulary: heck no!• Most scientific vocabulary are “little words”, or

roots, that are linked together • If you learn the meanings of these roots, you'll

find scientific vocabulary much easier to understand!

The Language of Sciencethese words will not be on the test

What is hydrology?What is a cytoskeleton?What is hyperthyroid?What is abiotic?What is hypodermic?

Learning roots will help in EVERY part of your college career! Take this time in BI101 to familiarize yourself with roots!

The Nature of Science• Humans have a natural spirit of inquiry, driving

science

– We start this as babies, this is how we learned many things!

– Both types of inquiry are important! Discover through both experience and study.

The Nature of Science

• Scientific thinking is objective and values evidence– W2L: What does it mean to be objective?– W2L: What kinds of things can be judged

objectively? What about subjectively?

The Nature of Science

• Science:• is a body of knowledge• is an evidence-based

process for acquiring knowledge

• deals with the natural world

• is based on evidence that can be demonstrated through observation and/or experiments

The Nature of Science

• The process that generates scientific knowledge is called the scientific method

• The scientific method is used in all areas of science

An Example of the Scientific

Method

You have observed that some fish swim slower than others.

The Nature of Science: Observations

• The process of science begins with an observation of the natural world

• An observation is a description, measurement, or record of any object or phenomenon

• An observation must be reproducible

An Example of the Scientific

Method

You develop a hypothesis that states: the faster a fish swims, the larger gill area is relative to body size.--Does this hypothesis make sense?

The Nature of Science: Hypotheses

• A scientific hypothesis is an informed, logical, and plausible explanation about the natural world

• Must be testable!

An Example of the Scientific

Method

You predict that: If a fish swims faster than another fish then the faster fish will have a larger gill area relative to its body size when compared to the slower fish.

The Nature of Science: Predictions

• Using the hypothesis make a prediction in an “if-then” statement

• Does not have to be an “if-then” statement but it is easier to write this way.

An Example of the Scientific

Method

You test your hypothesis by measuring the following on many types of fish: • Gill area • Body size

W2L: Why test many types of fish?

The Nature of Science: TestUsing Good Experimental Design

• An experiment is a repeatable manipulation of one or more aspect of the natural world by experimenters

• In a well designed experiment:– only one independent variable is manipulated at a

time– The experiment is controlled

The Nature of Science: Independent vs. Dependent Variable

• The dependent variable is effected by the independent variable.

• Remember only one independent variable is manipulated at a time

• What would happen if we tested two?

The Nature of Science: Independent vs. Dependent Variable

• In this experiment which is the independent and dependent variable?Hint: “I” determine the independent variable as the researcher.• In an experiment, only one

independent variable is manipulated at a time. Why?

The Nature of Science: Independent vs. Dependent Variable

• W2L: Let’s graph this!– Which variable is on the x-

axis?– Which variable is on the y-

axis?

The Nature of Science: Controlled Experiment• A controlled experiment:

– Comparable in all respects except one or more group(s) are exposed to systemic change and one is not

• Control group:– No change in independent

variable• Treatment group:

– Independent variable is manipulated by the researcher

An Example of the Scientific

Method

What were your results?

Is your hypothesis supported or not?

An Example of the Scientific

Method

Now you have another observation that you can base another hypothesis on.

An Example of the Scientific

Method

What if the data doesn’t support the hypothesis?• This is when science

gets even more fun!! Sometimes

1*

9*

30*

50*

18

*this data has been changed and does not reflect what actually occurs in nature

The Nature of Science: Scientific Theory

• A scientific theory is a body of knowledge that has stood the test of time

• 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• A scientific fact is a direct and repeatable

observation about the natural world

Just a theory?• When we use the word "theory" in everyday

life, we usually mean an idea or a guess, but the word has a much different meaning in science…

• Some theories in Biology:– Cell Theory– Theory of Natural Selection– Germ Theory

Characteristics of Living Organisms

• All living organisms share a set of common characteristics

• Living organisms: – Are composed of one or more cells– Reproduce using deoxyribonucleic acid (DNA)– Obtain energy from their environment to support

metabolism– Sense and respond to their environment– Maintain homeostasis– Are capable of evolving as a group

Characteristics of Living Organisms: Cells

• Cells:– Basic unit of life – Cells enclosed by a water-repellent

layer called the plasma membrane

Characteristics of Living Organisms: Reproduce via DNA

• DNA:– DNA is genetic

material that contains all the instructions for building new organisms

– Passes information from parent to offspring

Characteristics of Living Organisms: Energy from the Environment

• All organisms need energy to live, they get this energy from their environment.

• Plants are producers:– convert energy from

the sun into chemical energy

• Consumers use energy from other consumers or directly from producers– Ex: cat eats mouse and gets

some of the energy that the mouse contained

Characteristics of Living Organisms: Homeostasis

• Keeping the balance• Organisms sense and

respond to their environment in order to maintain constant internal conditions through a process called homeostasis

Characteristics of Living Organisms: Groups Evolving

• Evolution allows an organism to survive and reproduce better than competing organisms

In biology there is a hierarchy in order from less to more complex.