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Contents
1 Learning about Human
Biology 1
1.1 Shared Features of Life 2
1.2 Our Place in the Natural World 3
Humans have evolved over time 3
Humans are related to all other living things—but we
have some distinctive characteristics 3
1.3 Life’s Organization 4
Nature is organized on many levels 4
Organisms are connected through the flow of energy
and cycling of materials 4
1.4 Using Science to Explain Natural Events 6
Scientific studies are systematic 6
Doing experiments is a common way to test a
scientific prediction 7
In science, logic rules! 7
1.5 Critical Thinking in Science and Life 8
Evaluate the source of information 8
Evaluate the content of information 8
1.6 Science in Perspective 9
It is important to understand what the word theory
means in science 9
Science has limits 9
1.7 Connections: Homeostasis 10
1.8 Focus on Health: Living in a World
of Disease Threats 10
2 Chemistry of Life 15
2.1 Atoms and Elements 16
Elements are pure substances 16
Atoms are composed of smaller particles 16
Isotopes are varying forms of atoms 17
2.2 Science Comes to Life: PET Scanning—
Using Radioisotopes in Medicine 17
2.3 Chemical Bonds: How Atoms Interact 18
Atoms interact through their electrons 18
Chemical bonds join atoms into molecules 18
Molecules may contain atoms of a single element or
of different elements 19
2.4 Important Bonds in Biological Molecules 20
An ionic bond joins atoms that have opposite
electrical charges 20
In a covalent bond, atoms share electrons 20
A hydrogen bond links polar molecules 21
2.5 Water: Necessary for Life 22
Hydrogen bonds make water liquid 22
Water can absorb and hold heat 22
Water is a solvent 23
2.6 Focus on Health: Antioxidants Help Protect
Cells 23
2.7 Acids, Bases, and Buffers: Body Fluids
in Flux 24
The pH scale indicates the concentration of hydrogen
ions in fluids 24
Acids give up H^1 and bases accept H^1
A salt releases other kinds of ions 25
Buffers protect against shifts in pH 25
2.8 Molecules of Life 26
Biological molecules contain carbon 26
Carbon’s key feature is versatile bonding 26
Functional groups affect the chemical behavior of
organic compounds 26
Cells have chemical tools to assemble, break apart,
and rearrange biological molecules 27
2.9 Carbohydrates: Plentiful and Varied 28
Simple sugars are the simplest carbohydrates 28
Oligosaccharides are short chains of sugar units 28
Polysaccharides are sugar chains that store energy 29
2.10 Lipids: Fats and Their Chemical Relatives 30
Fats are energy-storing lipids 30
Phospholipids are basic building blocks
of cell membranes 31
Cholesterol and steroid hormones are built
from sterols 31
2.11 Proteins: Biological Molecules with
Many Roles 32
Proteins are built from amino acids 32
The sequence of amino acids is a protein’s
primary structure 33
2.12 A Protein’s Shape and Function 34
Proteins fold into complex shapes that determine
their function 34
A protein may have more than one polypeptide chain 34
Glycoproteins have sugars attached and
lipoproteins have lipids attached 34
Disrupting a protein’s shape prevents it from
functioning normally 35Copyright 2016 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).