Chapter 4 Lesson 3 Cycles of Matter
Study Guide
Matter moves between the environment and living things in all cycles of matter (water, carbon
and nitrogen).
Water Cycle:








Evaporation is a change of water from liquid to vapor.
Condensation is the change of water from vapor to liquid.
Precipitation is when water falls from atmosphere back to Earth in the form of rain, snow,
sleet or hail to the land and oceans.
Most precipitation that falls to Earth’s surface falls directly into oceans.
Run off will occur when water that falls on land then flows into rivers, lakes and
oceans.
Transpiration is when plants release water vapor
Infiltration is the process of water moving from the surface through the layers of soil and
rock until it reaches groundwater reservoirs.
Groundwater is water that is stored between or within rocks below the surface.
Carbon Cycle:










All organic molecules contain carbon.
Carbon is important to living things because it transports the material cells use for energy.
Carbon from the environment becomes a part of living organisms through
photosynthesis.
Most animals get the carbon they need by eating plants.
Photosynthesis is when plants use carbon dioxide from the air to make sugars and release
oxygen into atmosphere.
Combustion is the burning of a substance that releases carbon dioxide into atmosphere.
When humans burn fuel and cut down trees they increase the level of carbon dioxide in
the atmosphere.
Cellular Respiration is when sugar molecules are broken down by plants to release
energy. Carbon dioxide and water are released as byproducts of this process.
Combustion, respiration and decomposition all release carbon dioxide into the
environment. Photosynthesis does not.
Decomposition is the breakdown of substances into simpler molecules.
Bacteria breaking down organic matter and returning carbon dioxide and water to the
environment is an example of decomposition.
Nitrogen Cycle:







78% of the Earth’s atmosphere is nitrogen gas, but most organisms cannot use it in this
form.
Nitrogen is important to living things because it builds proteins/new cells.
Nitrogen gas must be chemically transformed (“fixed” or combined) before it can be
used in the form of a compound by plants.
Most animals get nitrogen by eating other organisms.
Bacteria that live in nodules on the roots of legumes (often just said to live in the soil)
have the important function of nitrogen fixation.
Legumes = beans (especially soy beans), clover, alfalfa and peanuts.
Lightening can also cause nitrogen fixation.

Some bacteria who do the reverse of nitrogen fixation, or denitrification. That is,
they return nitrogen to its gaseous form. This frequently happens during
decomposition.
Also be able to explain:



Two ways that deforestation puts more CO2 in the atmosphere.
* plants are gone so there is no longer photosynthesis which would remove CO2
from atmosphere
* burning of trees creates more CO2 through combustion
Two problems with burning fossil fuels
*burning fossil fuels releases large amounts of stored carbon compounds through
combustion
* non-renewable = once we burn them they are gone
The Law of Conservation of Matter and how it applies to each of the cycles.
* matter remains constant over time, therefore the amount of matter cannot
change= it cannot be created (added) or destroyed (removed)
* the amount of water, carbon and nitrogen remains constant. New
atoms/molecules that contain them are not created, nor can they be
destroyed… they are simply recycled and move from one form and from reservoir
to reservoir over time through various processes