BSCS Science:
An Inquiry Approach
Level 2
First edition, © 2008 by BSCS
Unit 4 Overview
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Unit Overview
In unit 4, Sustaining Earth Systems, students will make
connections between what they have learned about the
physical and living worlds during this program. Students
have learned what systems are and how interactions can
change systems. Now they will look into how interactions between the physical and living world influence
ecosystems. The processes that occur in ecosystems are
not only important for maintaining the systems, but also
for providing resources that humans depend on.
The unit begins by looking at populations and what
influences population sizes. Interactions between populations and the abiotic environment make up ecosystems.
Students will learn that important processes such as the
cycling of matter and the flow of energy occur in ecosystems. Then students will discover that human populations
are influenced by the same factors as other organisms,
as we face the challenge of maintaining the supply of
resources we need to survive. Finally, students will think
about how human activities alter processes in ecosystems
and how this might affect environmental quality.
Strategies for the Unit Engage
Use this activity to transition your students from
geochemical cycles and interactions in earth systems to
how these interactions influence ecosystems and affect
the functions they provide. Begin by recording the names
of the four chapters of unit 3, Moving Matter, on four
separate large sheets of paper. Then ask students what
geochemical cycles they learned about in each of the chapters. Record their ideas on the sheets of paper. Students
should recall that they learned about matter moving in
the water cycle, in the carbon cycle, during ice ages, and
in relation to plate tectonics. Then ask students to think
of examples of how human and nonhuman populations
are related to the movement of matter. For example, you
could have students use two sheets of paper to fill out a
table in their science notebooks similar to figure T14.1.
Explain to students that in unit 4, they will learn about
how organisms depend on ecosystems on Earth and how
humans can affect those ecosystems.
Goals for the Unit
The overarching goals for unit 4 are for students to
understand that populations grow, ecosystems provide
important functions for life on Earth, human populations
depend on the resources ecosystems provide, and human
activities alter natural processes in ecosystems and affect
environmental quality.
As students learn to meet these goals, they will also
refine their abilities and understandings of scientific
inquiry, such as designing investigations, creating and
analyzing tables and graphs, formulating explanations,
and understanding that scientists are influenced by current
and historical scientific knowledge.
Names of Chapters
Chapter 14: Population Interactions
Chapter 15: Earth’s Capacity
Chapter 16: Sustaining Earth’s Environmental Quality
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What
matter is
moving?
Chapter
Are living
organisms
involved in the
movement of
matter? Explain
why or why not.
How does this
movement of
matter affect
nonhuman
populations?
How does this
movement
affect human
populations?
Can humans
have an effect on
this movement?
Explain why or
why not.
Chapter 10,
The Water
System
Water
Yes. Plants
contribute to the
water cycle through
transpiration.
Organisms also
contribute small
amounts to the
water cycle through
respiration and
decay.
All living organisms
need water to
survive. Some
organisms need
water for habitat as
well.
Humans need
water for their
bodies to function,
but also use water
for transportation,
manufacturing, and
recreation.
Yes. Humans can
affect the water
cycle by using large
amounts of water,
by transporting
water to cities, and
by polluting water.
Chapter 11,
Carbon on
the Move
Carbon
Yes. Plants
contribute to the
carbon cycle by
making carbon
compounds during
photosynthesis.
Animals contribute
to the carbon cycle
through respiration
and decay.
Plants need
carbon from
the atmosphere
to make their
own food in the
form of carbon
compounds.
Carbon molecules
are the building
blocks for all living
organisms.
Humans rely on
carbon for their
bodies to function,
for many products
they use, and for
fuel.
Yes. Humans can
affect the carbon
cycle by burning
fossil fuels.
Chapter 12,
Evidence for
the Ice Ages
Oxygen
isotopes and
water
No. The record of
oxygen isotopes is
stored in forams,
but organisms are
not responsible for
the movement of
oxygen isotopes.
The amount of solar
radiation entering
the earth system
determines the ratio
of heavy to light
oxygen isotopes.
Different organisms
live during periods
of glacials or
interglacials
because the
climate is different.
During an ice age,
humans would
have to survive in
a different climate
with different
organisms.
No. Glacial
and interglacial
cycles occur over
thousands of
years and result
from changes in
the amount of
incoming solar
radiation. Scientists
are investigating
whether humans
are influencing the
cycles today.
Chapter 13,
Time for
Change
Tectonic
plates
No. Tectonic plates
move as a result of
mantle convection.
When tectonic
plates shift, land
bridges sometimes
form that can allow
animals to migrate
to new regions.
When earthquakes
or other events
occur along the
edges of tectonic
plates, structures
created by humans
may be destroyed.
No. Humans cannot
affect tectonic plate
movement because
it is the result of
mantle convection.
䉱 Figure T14.1 Table to connect what students know about the movement of matter to populations of organisms. Use questions like these
to prompt students to think about how living organisms are connected to the movement of matter.
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Unit 4
Sustaining Earth Systems