Activity 7: Background Information
The Water Cycle
Where there is water, there is life. Living things on Earth have a connection with water and water likewise is linked with them. Plants absorb water through their roots and they transpire and lose water into the atmosphere. Animals get their water by drinking it or by processing their food. Living things perform cellular respiration and produce water as a byproduct. This water
is also released into the atmosphere. Another source is the evaporation of water from other bodies of water. All of these contribute to the water vapor in the atmosphere. With cooler temperature, the water vapor goes through the process of condensation. This is followed by precipitation that allows the water, either in liquid form as rain, or solid form as snow or hail, to return to Earth.
Transpiration
Plants are rooted where they are and the only way they can get food is by making
it themselves. They do this by utilizing the Sun’s energy in the process of photosynthesis. Energy that the plants need in order to maintain their daily functions come from the very food that they synthesized. This process of getting energy is cellular respiration.
A byproduct produced in cellular respiration is water. As the plants take in carbon dioxide through their leaf openings called stomata, water in the form of water vapor leaks out. When leaves lose water into the atmosphere, the process is called transpiration.
This activity focuses on the skills involved
in doing an experiment. The students,
as they set up and measure transpiration rates, are given the opportunity to figure
out the factors that could affect this rate.
As they do their experiment, the students
are encouraged to look for possible sources of experimental errors. |