holt biology chapter 1 biology and you section 2: scientific methods - quia · holt biology chapter...

Holt Biology Chapter 1

Biology and You

Section 2: Scientific Methods

Adapted from Holt Biology 2008

Chapter 1 Section 2: Scientific Methods

Key Vocabulary Terms


Observation

The process of obtaining information by using the senses; the information obtained by using the

senses.


Hypothesis

A testable idea or explanation that leads to scientific investigation.

A possible explanation that can be tested by

observation or experimentation.

Hypotheses are not guesses.


Theory

A system of ideas that explains many related

observations and is supported by a large

body of evidence acquired through

scientific investigation.

Hypothesis or Theory?

In everyday language, there is little difference between a hypothesis and a theory. But in science, the meanings

of these words are more distinct. A hypothesis is a specific, testable prediction for a limited set of

conditions. A theory is a general explanation for a broad range of data. A theory can include hypotheses

that have been tested and can also be used to generate new hypotheses. The strongest scientific theories

explain the broadest range of data and incorporate many well-tested hypotheses.


Experiment

A procedure that is carried out under

controlled conditions to discover,

demonstrate, or test a fact, hypothesis,

theory, or general truth.


Control Group

In an experiment, a group that serves as a

standard of comparison with another group to which the control group is identical

except for one fact.


Variable

An element, feature, or factor that is liable

to vary or change.


Controlled Experiments

A procedure that tests one factor at a time

and that uses a control group and an experimental group.


Experimental Group

Identical to the control group except for one

factor, or variable.


Independent Variable

The single factor that scientists change in an

experiment.


Dependent Variable

Factors that may change in response to

the independent variable.


Chapter 1 Section 2: Scientific Methods

Supplementary Words


Chapter 1 Section 2:

Scientific Methods

Notes

Beginning a Scientific Investigation

Most scientific investigations begin with observations

that lead to questions.



Observation is the act of noting or

perceiving objects or events using the

senses.



YOUR TURN

With a partner, read the Chapter 1 Section 2 Active Reading – Scientific Methods

1st - Take turns reading the questions aloud to each other, alternating questions.

2nd - Take turns reading the selection aloud to each other, alternating sentences or paragraphs.

Adapted from Holt Biology 2008 Adapted from Holt Biology 2008

YOUR TURN

As you read discuss the content.

Reread and discuss each question. Write down the best answer to the question using full descriptive sentences.

• Be prepared to share your ideas with the class.


2


To answer a question, scientists

first formulate a hypothesis that

leads to scientific investigation.



A hypothesis is a possible explanation

that can be tested by observation or experimentation.


Scientific Experiments

An experiment is a procedure that is carried out under

controlled conditions to test a

hypothesis.



A controlled experiment tests

one factor at a time and uses a control

group and an experimental group.


Control Group

A control group is a group that serves as

a standard for comparison in an

experiment.


Experimental Groups

The experimental groups are identical to the control group

except for one factor, called a

variable.


Independent Variable

The single factor that scientists change in an

experiment is called the independent

variable.



Factors that may change in response to the independent variable are called

dependent variables.



Scientists analyze changes to the

dependent variables in order to

understand how the independent

variable affects the system that they are

studying.



There are often cases in which

experiments are not possible or not

ethical.



In these cases, researchers perform

studies.



In a study, researchers gather

data about a system by making

observations rather than by

manipulating independent

variables. Adapted from Holt Biology 2008


After conducting an experiment,

researchers analyze their results to learn whether the results

support their hypothesis or not.



Scientists draw conclusions that

explain the results of their

experiments.



Scientists verify their conclusions by

conducting their experiments many

times and by checking to see if

other scientists have found similar

results. Adapted from Holt Biology 2008

Bias

Every person has his or her own point of view. A particular

point of view is called a bias.


Bias

Scientists try to prevent bias from

affecting their work, but bias can still

influence an experiment.


Bias

Sources of funding, personal

involvement in a product, and other conflicts of interest

can affect an experiment.



It is wise to view all scientific claims in their context and think critically about

them.


Scientific Theories

In science, a theory is a system that explains many

related observations and is

supported by a large body of

evidence.


Scientific Theories

The main difference between a theory and a hypothesis is that a

hypothesis is a specific, testable prediction for

a limited set of conditions and a

theory is a general explanation for a

broad range of data. Adapted from Holt Biology 2008

Scientific Theories

Constructing a theory often

involves considering contrasting ideas

and conflicting hypotheses.


Scientific Theories

If the results of a scientific

experiment can be reproduced many

times, the research may help

develop a new theory.


Scientific Theories

Future research may cause a theory to be

revised or even rejected.


Scientific Theories

By investigating and challenging

theories, scientific understanding

grows.


Hypothesis or Theory?

In everyday language, there is little difference between a hypothesis and a theory. But in science, the meanings

of these words are more distinct. A hypothesis is a specific, testable prediction for a limited set of

conditions. A theory is a general explanation for a broad range of data. A theory can include hypotheses

that have been tested and can also be used to generate new hypotheses. The strongest scientific theories

explain the broadest range of data and incorporate many well-tested hypotheses.

Think, Share, Write #2

How does the scientific use of the word theory differ from how it is

used by the general public?

Think, Share, Write #2

How does the scientific use of the word theory differ from how it is

used by the general public?

Answer

Summary

Most scientific investigations begin

with observations that lead to questions.


Summary

Scientists can conduct controlled experiments and perform studies in

order to test a hypothesis.


Summary

The main difference between a theory and a hypothesis is that a

hypothesis is a specific, testable prediction for a

limited set of conditions, while a theory is a general explanation for a

broad range of data. Adapted from Holt Biology 2008

Section Review

1. Summarize the processes that scientists often use when beginning scientific investigations.

Section Review

2. Describe two (2) ways that scientists test hypotheses.

Section Review

3. Explain the difference between a hypothesis and a theory.

Section Review Critical Thinking

4. Analyzing Methods Provide one example of a case in which an experiment would not be possible and one example in which an experiment would not be ethical.

Section Review Critical Thinking

5. Forming Hypotheses - A friend notices that her dog is getting thinner even though she has not changed how much she feeds him. Propose three testable hypotheses to explain the dog’s weight loss.

Section Review Methods of Science

6. Designing an Experiment - Suppose that Paine had hypothesized that the Canada geese in Chicago were not reproducing at a normal rate. What experiment could he use to test whether the geese in Chicago were less fertile than geese elsewhere?

holt biology chapter 1 biology and you section 2: scientific methods - quia · holt biology chapter...

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