Transcript Document

UNIT FOUR: Matter and its Changes
 Chapter 12 Atoms and the Periodic
Table
 Chapter 13 Compounds
 Chapter 14 Changes in Matter
 Chapter 15 Chemical Cycles and
Climate Change
Chapter Fifteen: Chemical Cycles and
Climate Change
 15.1 Chemical Cycles
 15.2 Global Climate Change
Section 15.1 Learning Goals
 Trace the pathways by which elements are
recycled in nature.
 Identify specific processes associated with
chemical cycles.
 Discover how living organisms within ecosystems
are affected by or interact with Earth’s chemical
cycles.
Investigation 15A
Carbon Dioxide and Living Things
 Key Question:
 How do living things
exchange carbon dioxide?
15.1 Chemical Cycles
 The Earth’s elements essential for living
things are called nutrients.
 Living things need macronutrients in
large quantities while micronutrients are
needed in small quantities.
15.1 Chemical Cycles
 Over time, these
elements are
transported through
the living and
nonliving parts of
our planet in sets of
processes called
chemical cycles.
15.1 Chemical Cycles
Examples of these cycles include the:
1. oxygen cycle,
2. carbon cycle,
3. nitrogen cycle, and
4. phosphorus cycle.
Even before life appeared on Earth millions of
years ago, elements were recycled.
15.1 How living organisms affect
cycles
 An ecosystem consists
of a group of living
things and their physical
surroundings.
 The Sun is the main
energy source for
ecosystems.
Can you list some living and
nonliving parts in this tropical
rainforest ecosystem?
15.1 Photosynthesis
 Photosynthesis is the process by which
plants and some other organisms convert
the Sun’s energy to chemical energy.
15.1 Living parts of an ecosystem
 A producer is a living thing, like a plant,
that can take the Sun’s energy and store it
as food.
15.1 Living parts of an ecosystem
 A consumer must feed on
other living things to get food
and energy.
 An herbivore is a consumer
that eats only plants.
 A carnivore is a consumer that
eats only animals.
 A consumer that eats both
plants and animals is called an
omnivore.
15.1 Living parts of an ecosystem
 A decomposer is a
living thing that
consumes waste and
dead organisms to
get energy.
 Decompose means
“to break down”.
15.1 Living parts of
an ecosystem
 A food chain shows how
each member of an
ecosystem gets its food.
 A simple food chain
links a producer, an
herbivore, and one or
more carnivores.
Which is the herbivore?
15.1 Pollution in ecosystems
 Human activities
create toxic
pollutants (toxins).
 High concentrations
of toxins impact
living things.
15.1 Pollution in ecosystems
 Mercury from power
plants falls to Earth
with rain and ends up
in lakes and oceans.
 As toxic mercury is
concentrated up the
food chain, it can
accumulate to
dangerous levels if
ingested by humans.
15.1 The water and oxygen cycles
 Living things need
water and sunlight.
 Nature allows water to
recycle so it can be
used in many
ecosystems.
 Water supply depends
on the water cycle.
15.1 The water and oxygen cycles
 Like water, oxygen is
essential for living
things.
 During photosynthesis,
plants release oxygen
into the atmosphere.
 During respiration,
plants or animals use
oxygen to store energy.
15.1 The carbon cycle
 Trace the pathways through which carbon is
released and absorbed in the diagram below:
15.1 The nitrogen cycle
 Nitrogen is important to
living things because it
is used to make amino
acids, the building
blocks of all proteins.
 Approximately 78
percent of Earth’s
atmosphere is nitrogen
gas (N2).
15.1 The phosphorus cycle
 Phosphorus is
essential for cell
replication,
metabolism, and
structures.
 Phosphorus from
minerals is absorbed
by the roots for use
by the plant.
 Animals obtain
phosphorus by
eating plants.
15.1 Cycles interconnect
 Cycles do not have
beginning or ending
points.
 Because organisms are
not 100% efficient at
using what they
consume, they release
heat energy as they
metabolize nutrients.