Lesson 5.2 - Cycles of Matter

Plants and animals have many nutrient requirements to live and reproduce.  Every nutrient and element on earth is limited in supply.  The nutrients and elements must be recycled so that life can continue on Earth.  Nature recycles these nutrients and elements and puts human efforts at recycling to shame.  You will begin your study of cycles of matter by learning how water is cycled in nature. 

Read The Cycles of Matter and Water Cycle on page 248. Then, answer the following questions.

 

Question 1. What is meant by the water cycle?

Question 2. When plants and animals use water, some of it is contaminated with wastes of the living process.  How is the water purified so that it can be reused by living organisms?

Question 3. What are the steps in the water cycle?

Question 4. In the diagram of the water cycle on page 248, some of the water seeps into the ground and is called ground water.  Is ground water lost from the water cycle?

Question 5. What is the driving force behind the water cycle?

 

Check your answers with those that follow.

 

 

 

 

 

 

 

 

 

 

 

 

Answers to Questions:

Question 1. What is meant by the water cycle?

The water cycle refers to the continued purification and reuse of water on Earth.

Question 2. When plants and animals use water, some of it is contaminated with wastes of the living process.  How is the water purified so that it can be reused by living organisms?

When water evaporates, it forms water vapour, which is pure water.  The wastes are left behind.  The transpiration from plants and water vapour exhaled from animals is also pure water in the form of water vapour.

Question 3. What are the steps in the water cycle?

There is no real beginning step because it is a cycle.

One step is the water falling as rain, snow, or any other form of precipitation.  Another step is the return of water to the atmosphere by evaporation and transpiration.

Question 4. In the diagram of the water cycle on page 248, some of the water seeps into the ground and is called ground water.  Is ground water lost from the water cycle?

No, the ground water may be removed from the water cycle for long periods of time, but it returns eventually to the surface through springs and artesian wells as well as by many other methods.  Humans are pumping vast quantities of ground water that is used for many human activities.

Question 5. What is the driving force behind the water cycle?

The sun is the driving force behind the water cycle.  The sun provides the energy needed to evaporate the water. 

 


Go to the next page to continue Lesson 5.