The Biosphere

What is the biosphere?


DS1.2 The biosphere
Earth is a unique planet because, as far as we know, Earth is the only planet where living things survive. The biosphere makes this possible. It is a thin layer of air, land, and water on or near the earth’s surface. This thin layer is where all life on Earth exists as well as the environments where that life lives. Anything outside of the biosphere is considered to be uninhabitable. This means that nothing living can survive outside of the biosphere.

Each part of the biosphere—the air, land, and water—has a specific name and characteristics.

D1.2 Parts of the atmosphere
The atmosphere is the name given to the layer of air found in the biosphere. The atmosphere is a mix of nitrogen, oxygen, and small amounts of other gases. This layer takes up the space from the earth’s surface to approximately 800 km above the earth’s surface. The atmosphere itself can be split into four layers: the thermosphere, mesosphere, stratosphere and troposphere. Image D1.2 shows a fifth layer that we will not study in this course. The majority of the gases found in the atmosphere are concentrated in the stratosphere and troposphere.

Have you ever heard the term “thin air”? This expression is used to describe air where there is less oxygen present. As you get farther up in the atmosphere, the concentration of oxygen becomes less and less. Even within the stratosphere and troposphere, humans can sense a noticeable difference in the makeup of the air as they get farther from the earth’s surface. This is because humans find it more difficult to breathe as they get farther from the earth’s surface.

Organisms living in the atmosphere are generally found in the troposphere, as this is the layer closest to Earth’s surface. There have been clumps of microorganisms found in the stratosphere, but nothing living has been found in the mesosphere or thermosphere.
D1.3 Mount Everest is the tallest mountain on Earth

  Did You Know?

D1.4 Machu Picchu, 2430 metres above sea level
If we travel too far up into the atmosphere, we can actually become quite sick. This sickness is caused by low amounts of oxygen in the air and can occur any time you are 2 438 metres or higher above sea level. People who are planning to travel to or exercise in areas of high altitude need to train and prepare their bodies.
The atmosphere is mostly made of nitrogen (N2) and oxygen (O2). They make up 78% and 21%, respectively. The remaining 1% of the atmosphere is made up of many other gases, including but not limited to argon (Ar), carbon dioxide (CO2), methane (CH4), neon (Ne), and helium (He). 
©Wikimedia Commons
D1.5 Gases in the atmosphere

D1.6 The Hydrosphere
The hydrosphere is the name given to the water found in the biosphere. The water in the hydrosphere can be found as a liquid, as water vapour, or as ice. This water is generally found on or near Earth’s surface and includes oceans, lakes, rivers, streams, underground reservoirs, clouds, humidity, and moisture in the air. Interestingly, about 97% of the water found on Earth is in the form of salt water. This is interesting because most living organisms require fresh water to survive.

Some scientists consider the frozen water on Earth to be an additional category of water called the cryosphere.

Since Earth is 70% water and only 30% land, the hydrosphere is a large part of the biosphere. Most of the organisms on Earth require water to survive and so the hydrosphere is tied very closely to life on Earth. Many organisms, from algae to whales, live in one form of the hydrosphere or another. The hydrosphere also plays an important role in how the sun’s energy is distributed.
D1.7 Earth is 70% water

D1.8 The Lithosphere
The lithosphere is the name given to the land found in the biosphere. It is made of rocks, minerals, and elements, and many organisms call the lithosphere home. The lithosphere contains Earth’s crust that forms the land and the bottom of the sea. Remember, the earth itself is made of many different layers from the center of the earth to the surface of the earth. These layers are called the mantle and the core. The lithosphere includes the top layer of the earth’s mantle as well as the crust.

Atmospheric dust can also be part of the lithosphere. Atmospheric dust is solid particles that can be non-living matter from Earth’s crust or living particles such as microorganisms and pollen. Only the non-living particles are considered part of the lithosphere.

  Digging Deeper

Earth’s mantle makes up a very large portion of the planet. It is an amazing 2 900 km thick and makes up 84% of Earth’s total volume. Go to the following link for more information on this topic. https://www.nationalgeographic.org/encyclopedia/mantle/

Learn More
D1.9 Earth’s structure

  The Components of the Biosphere Interact

How do the atmosphere, hydrosphere, and lithosphere relate to each other?


D1.10 All the parts of the biosphere interact
It is important to note and to understand that the three components (and each component of those three components) are constantly interacting with one another. It is through this interaction that the atmosphere, hydrosphere, and lithosphere form the biosphere. Each component is not found separate from the other components, but rather, all the components tend to be mixed together. For example, water vapour is found in the atmosphere, and a really muddy river or lake is a mixture of both the lithosphere and the hydrosphere.

  Read This

Please read pages 343 to 346 in your Science 10 textbook. Make sure you take notes on your readings to study from later. You should focus on the different parts of the biosphere and their major characteristics. Remember, if you have any questions or 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. Complete the following chart:

    Part of the Biosphere
    		What It Contains
    		How It Supports Life
    		One Other Fact from Your Readings
    atmosphere
    lithosphere
    hydrosphere

    Part of the Biosphere
    		What It Contains
    		How It Supports Life
    		One Other Fact from Your Readings
    atmosphere It is the air above the earth’s surface,  which includes the thermosphere, mesosphere, stratosphere, and troposphere. It contains nitrogen and oxygen as well as other gases. It provides the oxygen that living organisms need to survive and contains the warmth needed for survival. Most of the gases and all of life are found in the stratosphere and troposphere (mostly troposphere).

    They ozone layer is found in the stratosphere.
    lithosphere It is Earth’s crust (land and the bottom of the sea) and the top layer of the mantel. It also contains the non-living particles in the atmospheric dust found in the atmosphere. It provides land for organisms to live on and feed off of.
    		It extends 100 km below Earth’s crust, into the mantle.

    It is mainly warmed by solar energy but also by Earth’s core.
    hydrosphere It contains water in all three states (vapour, liquid, and ice) and includes clouds in the atmosphere and underground reservoirs.
    		It provides water for organisms to live in or drink.
    		97% of the water on Earth is salt water. The remaining 3% includes all the rivers, lakes, streams, snow, ice, and glaciers.

    It is mostly warmed by the sun but also by Earth’s core.

  1. In your own words, define the term “biosphere.”

    Your answer should be a variation of the following: The biosphere contains all the living things on Earth and the environment that supports them. It includes all the air, land, and water on Earth.