Cells Are an Open System

There are two types of systems we discuss in biology: an open system and a closed system.



A4.3 Deer gaining nutrients through eating

  Did You Know?



A4.5 A Blue Thermos
 

There is a third kind of system called an isolated system. An isolated system does not exchange energy or matter with its environment. A great example of an isolated system is a thermos. When the lid is on a thermos, it does not exchange matter or energy with its surroundings. It is not a perfectly isolated system, as eventually the energy will leave the thermos and the contents inside will get cold—but it takes a very long time for this to happen!
An open system is one that is open to its environment. This means it gains nutrients from and exchanges energy and matter with the surrounding environment. Most animals are open systems since they eat what’s around them (gaining nutrients), get rid of waste, and decompose when they die (exchanging energy and matter).

A closed system is one that does not interact with its environment, except to exchange energy. One such example is Earth. Earth exchanges energy with space in the form of the sun’s rays. The materials of Earth cycle around the different layers of the earth, but most are rarely exchanged with space.

Cells are considered to be an open system because they are constantly interacting with the environment surrounding them. Just like an animal, they eat what’s around them, they get rid of waste, and they decompose when they die. Through this cycle, they are exchanging energy with their surrounding environment as well.

A4.4 Earth from space

  Read This

Please read pages 266 to 267 (not including Table C2.1) in your Science 10 textbook. Make sure you take notes on your readings to study from later. You should focus on the definition of an open system and how a cell meets that definition. Remember, if you have any questions or you do not understand something, ask your teacher!

  Practice Questions


Complete the following practice questions to check your understanding of the concept you just learned. Make sure you write complete answers to the practice questions in your notes. After you have checked your answers, make corrections to your responses (where necessary) to study from.

  1. What is the difference between an open system and a closed system?
An open system interacts with its environment to exchange energy and matter, excrete waste, and gain nutrients. A closed system does not interact with its environment, except to exchange energy.

  1. Provide an example of why a cell is an open system.
Any of the following are correct. You may think of other examples as well. Cells find food in their environment, gaining nutrients. Cells send their waste into the environment. Cells decompose, providing food and energy to the environment, exchanging both energy and matter.