Download Chapter 2 Cycles in Nature

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.
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 before it can be used 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 do the reverse of nitrogen fixation, or denitrification. That is, they
return nitrogen to its gaseous form.