Download Unit B, Chapter 1, Lesson 2

Chapter Outline
Unit B, “Systems and Interactions in Nature”
Chapter 1, “Cycles in Nature”
Lesson 2, “Why Is the Water Cycle Important?”, pgs. B14-B17
The Water Cycle
Seas, oceans, lakes, and rivers cover about _____75%__________ of Earth’s surface.
Define Water Cycle – how Earth’s water moves through the environment
Define Evaporation – when the heat of the sun changes liquid water on Earth’s surface
into water vapor
Define Condensation – when water vapor changes back into liquid water, usually high
above the Earth’s surface
Tiny droplets of water form a _____cloud__________.
If the air temperature on Earth is warm, the water will fall back as _____rain__________.
If the air temperature on Earth is cold, the water will fall back as ______snow_________.
Define Precipitation – any form of water that falls from clouds
All living organisms need ____water___________ to survive.
About how much of the human body is water?
70%
Where do plants get the water they need? Where do animals get the water they need?
Plants take in water through their roots in the soil.
Animals get water from lakes and streams or from the food they eat.
Define Transpiration – when plants give off water through their stomata
How do animals put water back into the environment?
From their lungs when they exhale and in their wastes
Humans and the Water Cycle
All the water on Earth today is the _____same__________ water that was here billions of
years ago.
Name three ways people use water:
1. Drinking
2. Bathing
3. Cooking
How much of Earth’s fresh water can be used? Where is most of it?
Less than 1%, most of it is frozen in ice caps and glaciers
How can we conserve water?
Take shorter showers
Turn off water while brushing teeth
Turn off water in between washing dishes