Chapter 1 Biology in the 21st Century

1.3 Scientific Thinking and Processes

KEY CONCEPT

Science is a way of thinking, questioning, and
gathering evidence.

1.3 Scientific Thinking and Processes

Like all science, biology is a process of inquiry.

• Scientists make careful and systematic observations.

• Scientists test their hypotheses and analyze their data.

• Scientists form a hypothesis as a possible answer to
a

question.

• Scientists record observations as data.

1.3 Scientific Thinking and Processes

Biologists use experiments to test hypotheses.

• Observational studies allow scientists to describe a

phenomenon.

1.3 Scientific Thinking and Processes

• Experimentals allow scientists to determine what causes

a phenomenon.

1.3 Scientific Thinking and Processes

– Independent variables are manipulated.

– Constants are conditions that are kept the same.

• Experimental studies allow scientists to determine what

causes a phenomenon.

– Dependent variables are observed and measured.

1.3 Scientific Thinking and Processes

A theory explains a wide range of observations.

• Theories explain a wide range of observations and

experimental results.

• A theory is supported by a wide range of scientific

evidence.

• Theories can change based on new evidence.

New evidence shows that ulcers are
caused by bacteria.

1.4 Biologists’ Tools and Technology

KEY CONCEPT

Technology continually changes the way biologists
work.

1.4 Biologists’ Tools and Technology

Imaging technologies provide new views of life.

• A microscope provides an enlarged image of an object.

stoma

– light microscopes (LM)

1.4 Biologists’ Tools and Technology

stoma

– scanning electron microscopes (SEM)

Imaging technologies provide new views of life.

• A microscope provides an enlarged image of an object.

– light microscopes (LM)

1.4 Biologists’ Tools and Technology

– transmission electron microscopes (TEM)

stoma

– scanning electron microscopes (SEM)

Imaging technologies provide new views of life.

• A microscope provides an enlarged image of an object.

– light microscopes (LM)

1.4 Biologists’ Tools and Technology

• Imaging technology is used in medicine.

– X-ray images

1.4 Biologists’ Tools and Technology

– magnetic

resonance
imaging (MRI)

• Imaging technology is used in medicine.

– X-ray images

1.4 Biologists’ Tools and Technology

– functional MRI (fMRI)

– magnetic

resonance
imaging (MRI)

• Imaging technology is used in medicine.

– X-ray images

1.4 Biologists’ Tools and Technology

Complex systems are modeled on computers.

• Computer models are used to

study systems that cannot be
studied directly.
– heart attacks

– effect of medicines on the

human body

– movement of water molecules

into and out of a cell

– spread of a disease through a

population

• Computer models are used when

experiments are not safe, ethical,
or practical.

Normal heartbeat

Heart attack

1.4 Biologists’ Tools and Technology

The tools of molecular genetics give rise to new
biological studies.

• A gene is a segment of DNA that stores genetic

information.

1.4 Biologists’ Tools and Technology

• Through our understanding of DNA, we can study

genetics on a molecular level.

– molecular genetics
– genomics