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Module 1
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Elements of Life

LEARNING GOALS LG 1.1 Matter and energy govern the properties of life.

LG 1.2 The atom is the fundamental unit of matter.
LG 1.3 Atoms combine to form molecules linked by chemical bonds.
LG 1.4 Carbon is the backbone of organic molecules.

ake a look around you. Everything you see and feel We will also look at the use and flow of energy. We will explore
Tis made of matter, the material that makes up physical how chemical bonds enable atoms to form a wide variety of

objects. Matter is anything that has mass and takes up space. molecules, which are chemicals made up of two or more

Matter may be a gas, a liquid, or a solid. Even you are made of atoms, and will examine the chemical properties of molecules
matter. To grow, reproduce, and maintain their organization, all that are used by all living things.
organisms exchange matter with their environment. They also
require energy. The study of biology is based on an understand- PREP FOR THE AP EXAM
®
ing of the pathways and transformations of matter and energy. FOCUS ON THE BIG IDEAS
Therefore, to understand why organisms look and act as they

do, we need to gain a basic understanding of matter and energy. ENERGETICS: Look for the elements that make up all
organisms, and the way in which organisms exchange these
In this module, we will examine the fundamentals of both. We elements with the environment.

will look at properties of the basic unit of matter, the atom .

1.1 Matter and energy govern earthquakes, erosion, or other geologic activities returned
the properties of life it to the atmosphere as carbon dioxide once again. Slowly
but surely, geologic processes on early Earth cycled carbon
Because organisms are composed of matter and require energy, from atmosphere to rocks and back again. This slow move-
it follows that organisms are subject to the physical laws and ment of carbon between Earth and atmosphere continues
principles that govern matter and energy. In this section, we today.
will first review some of the properties of matter and energy, Sometime between 4 and 3.5 billion years ago, as life
and how they flow through communities of living organisms. took hold on Earth, our carbon atom began to cycle more
rapidly— much more rapidly. Microorganisms were able
Flow of Matter to convert the carbon dioxide in the environment into

Let’s begin by following the path of matter as it flows through organic molecules, which are biological molecules that
living systems. Imagine that we could tag a carbon atom at contain carbon. Other microorganisms broke down organic
its moment of origin and then follow its trip through time molecules and returned carbon dioxide to the environment.
and space. Formed in a nuclear blast furnace deep within an To this day, carbon cycles continuously from the atmosphere
ancient star and then ejected into space as the star exploded and oceans to organisms and back again.
in death, our atom was eventually swept up with other mate- This intricately linked network of geological and bio-
rials to form Earth, a small planet orbiting a newer star we logical processes that shuttles carbon among rocks, soil,
now call the sun. Volcanoes introduced our carbon atom into ocean, air, and organisms is called the carbon cycle. Why
Earth’s early atmosphere as carbon dioxide (CO) . Slowly, focus on carbon? The carbon cycle provides an organizing

2
over millions of years, this carbon dioxide reacted with principle for understanding life on Earth. The chemistry
water and rocks, transferring the carbon from the air to the of life is, in no small part, the chemistry of carbon because
seafloor. Here, our atom sat for many millions of years, until organic molecules are made up of carbon.

26 UNIT 1 CHEMISTRY OF LIFE

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