Lesson
The "Raw Materials"......
Although there are 92 elements known to occur naturally on Earth, fewer than 20 elements are presently known to occur in the tissues of living things. Only 6 elements make up 99 % of human or pumpkin tissues.
Carbon, oxygen, hydrogen and nitrogen make up the vast majority of living tissue. These four elements are recycled between :
living organisms and the soil,
water
atmosphere
These elements are first taken up by plants or producers as raw materials and some oxygen is released to the atmosphere as a product of photosynthesis. The rest is converted into food and passed through the food web. As they pass through plants, consumers, and finally decomposers such as fungi and bacteria, they are then returned to the environment in a continuous recycling of materials. If recycling of these materials did not occur, life could not exist.
Recycling of Carbon
Recycling Through the Atmosphere....
The continuation of life depends on the continued recycling of the materials that make up the food that passed through the ecosystem. Some of these elements (carbon, oxygen, sulfur, nitrogen) are found in gaseous forms and their cycles involve the atmosphere. As a result they have a global nature.
Not Recycling Through the Atmosphere.....
Other elements (phosphorus, potassium, calcium,) generally recycle in a more localized manner since they do not have a gaseous form and therefore do not recycle by way of the atmosphere. One should also be aware that some of the elements may have:
- a short term cycle such as when carbon is transferred from animals to plants in the form of carbon dioxide
- and a long term cycle such as the transfer of carbon from a fossil fuel to a plant following combustion.
Carbon Cycle and Photosynthesis
Plants take carbon dioxide and water from their environment. They use the energy they capture from the sun to carry on a process known as photosynthesis which converts carbon dioxide and water into sugar (glucose) and oxygen.
Photosynthesis summarized in a chemical equation:
Carbon Cycle and Cellular Respiration
The oxygen, produced in photosynthesis, generally passes into the atmosphere. The sugar ( glucose) serves a food for all consumers in the ecosystem. The consumers body cells break down the sugar (glucose) in food in a process known as cellular respiration. During respiration, oxygen is taken in from the atmosphere and used to break down the sugar producing energy and carbon dioxide and water.
Respiration summarized in a chemical equation:
Sugar (glucose) + Oxygen ------> Carbon Dioxide + Water + Energy
C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy
What is the connection between Photosynthesis and Respiration?
What's made in Photosynthesis is used in Respiration and What's made in Respiration is used in Photosynthesis....
As you can see from the equations, photosynthesis and cellular respiration complement each other .That is,
the sugar and oxygen produced in photosynthesis is used for respiration.
and
the carbon dioxide and water produced in respiration is used in photosynthesis
During respiration, some of the carbon is released back to the environment as carbon dioxide. Plants undergoing photosynthesis use carbon dioxide and produce oxygen. Cellular respiration uses oxygen and produces carbon dioxide. Thus , the carbon is repeatedly cycled through both photosynthesis and cellular respiration back and forth. This balance is called the carbon cycle.
Carbon is central to life....
Not only do all living things contain carbon, it is the link that allows plants to transform sunlight into chemical energy. The sugar (glucose) produced during photosynthesis forms the basic substance that is transferred along food chains or through the pyramid of energy. As organisms grow they transform the carbon from the sugar into the living matter of their bodies.
Since the amount of carbon dioxide in the atmosphere is very small( 0.03%), it is essential to the continuance of life on Earth that the carbon contained in the bodies of living things be returned to the atmosphere when they die. Without the carbon cycle, we would quickly run out of carbon dioxide, plants could not trap sunlight, and life on Earth would cease.
Organic vs. Inorganic
Matter on Earth is placed in one of two categories, namely organic or inorganic. Organic substances always contain carbon and hydrogen, and often contain oxygen and nitrogen .Important chemicals that make up your body such as protein, sugar and fat are all considered organic.
Inorganic matter doesn’t contain a combination of carbon and hydrogen. For example, carbon dioxide(CO2), water(H20) and ammonia(NH3) are considered inorganic.
Inorganic Carbon Storage
A tremendous amount of inorganic carbon may be absorbed by the oceans, atmosphere, and Earth’s crust and stored there.
1.Atmosphere Storage:
The smallest percentage of the total amount of inorganic carbon( about 0.03%) is contained in the carbon dioxide in the air we breathe and is available for photosynthesis.
2.Ocean Storage:
A very large amount of inorganic carbon is found as dissolved carbon dioxide in the oceans. This is available to algae and other water plants for photosynthesis.
3.Earth's Crust Storage:
The largest storage of inorganic carbon is in sedimentary rocks, such as limestone, that have been formed from the remains of living things. In this form, carbon can be trapped in Earth for millions of years. Events such as volcanic activity can break down carbon containing rocks releasing carbon dioxide. Other events such as acid rain falling on exposed limestone will also cause the release of carbon dioxide into the atmosphere.
Organic Carbon Storage:
Organic carbon is also stored- in the bodies of living things. When living things die, their bodies decompose and the carbon is returned to the cycle in inorganic form. This normally occurs over a very short period of time. An exception to this is when large amounts of organic carbon is stored for very long periods in bogs. Because there is very limited oxygen in bogs, decomposition of plants and animals takes thousands of years. The result is that carbon remains locked away for many years in organic form. Carbon locked away in dead plant material is known as peat.
When peat becomes covered in sediment for long periods of time, this peat will become coal., a carbon containing fossil fuel. Other fossil fuels such as oil and gas contain organic carbon as well and are trapped in Earth’s crust for millions of years.
Human Activity
In modern times (past 200 years) people have discovered these fossil fuel deposits and have used them to supply our energy needs. Humans have also affected the carbon cycle by cutting down forests.
As a result of human activity, the amount of carbon dioxide is being produced at a faster rate than nature can recycle it. As a result of this imbalance, the amount of carbon dioxide in the atmosphere is increasing and at the same time, fewer trees results in a reduction in photosynthesis.
Earth is presently undergoing an enhanced greenhouse effect in which the atmosphere is gradually heating up. The gradual rise in temperature is predicted to have a disastrous effect on ecosystems. If the rise in temperature occurs too fast for organisms to adapt, widespread extinction of plants and animals may be the result. Extinction events have occurred in past history, but never as a result of human influence. We are the only species that can do something about the problems we have created.
Review what you have learned....
Click here to view an animation on the carbon cycle
Activity
Text Book Reading:
Nelson Science 10 Concepts and Connections: Section 1.8; pages 26-29
Activity 1:
Complete Understanding Concepts page 29 of text which is supplemented on page 37-39 of The Student Record of Learning
Activity 2:
Complete the Extension Activity on the Carbon cycle on page 33-36 in The Student Record of Learning
Activity 3:
Prepare a news report, or write an essay in which you answer the following question. How is the balance of nature affected by the influence of human activity on the Carbon cycle?
Activity 4:
Complete Black Line Master worksheet # 1.8
Test Yourself
- Which represents a major storage location for inorganic carbon?
- atmosphere
- land
- water
- living things
- Which process reduces the amount of carbon dioxide in the
atmosphere?
- cellular respiration
- burning of fossil fuels
- photosynthesis
- acid deposition
- Which is the most common element found in peat?
- carbon
- oxygen
- hydrogen
- nitrogen
- Which of the following areas does not store inorganic carbon?
- Atlantic ocean
- atmosphere
- coal mine
- living Fish
- Which of the following is a product of photosynthesis?
- carbon dioxide
- water
- light energy
- sugar
- Which of the following is used up in cellular respiration?
- oxygen
- water
- carbon dioxide
- nitrogen