1

The Carbon Cycle

Section 1.8

Pages 26-29

2

Elements

92 elements naturally occur on Earth Fewer than 20 elements occur in the tissues of

living things. Carbon, oxygen, hydrogen and nitrogen make

up the vast majority of living tissue. Recycled between

1. Living organisms and the soil,

2. Water

3. Atmosphere

3

Elements

Elements used by plants as raw materials and some like oxygen is released to the atmosphere.

The rest is converted into food and passed through the food web.

4

Elements

As elements pass through plants, consumers, and decomposers, they are returned to the environment.

If recycling of these materials did not occur, life could not exist.

5

Recycling

6

Carbon Cycle and Photosynthesis

7

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

Photosynthesis converts carbon dioxide and water into sugar (glucose) and oxygen.

8

Photosynthesis: Chemical Equation

9

Carbon Cycle and Cellular Respiration

The oxygen generally passes into the atmosphere. 

The sugar ( glucose) serves as a food for consumers.

Body cells break down the glucose in food in a process known as cellular respiration.

10

Carbon Cycle and Cellular Respiration

During  respiration, oxygen is taken in from the atmosphere

Oxygen is used to break down the sugar producing energy and carbon dioxide and water.

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Carbon Cycle and Cellular Respiration

Sugar (glucose) + Oxygen ------>  Carbon Dioxide + Water + EnergyC6H12O6              +       6O2      →      6CO2 +    6H2O   + Energy

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Photosynthesis and Respiration

What's made in Photosynthesis is used in Respiration

What's made in Respiration is used in Photosynthesis

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Photosynthesis and Respiration

Photosynthesis and cellular respiration complement each other .

The sugar and oxygen produced in photosynthesis is used for respiration.

The carbon dioxide and water produced in respiration is used in photosynthesis.

14

Photosynthesis and Respiration

15

Carbon Cycle

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.

16

Carbon Cycle

Thus, carbon is repeatedly recycled through both photosynthesis and cellular respiration. This balance is called the carbon cycle.

17

Organic vs. Inorganic

Organic substances always contain carbon and hydrogen. Chemicals such as protein, sugar and fat.

Inorganic matter doesn’t contain carbon and hydrogen. Carbon dioxide(CO2), water(H20) and ammonia(NH3)

18

Inorganic Carbon Storage

A tremendous amount of inorganic carbon may be absorbed by

1. The oceans

2. Atmosphere

3. Earth’s crust (soils)

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Inorganic Carbon Storage: The Oceans

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.

20

Inorganic Carbon Storage: The Atmosphere

The smallest percentage of the total amount of inorganic carbon

(about 0.03%) is contained in the carbon dioxide in the air we breathe.

Available for photosynthesis.

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Inorganic Carbon Storage: The Earth’s Crust

The largest storage of inorganic carbon is in sedimentary rocks, such as limestone.

 Volcanic activity and Acid Rain can break down carbon containing rocks releasing carbon dioxide.

22

Inorganic Carbon Storage (p. 28)

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Organic Carbon Storage

Organic carbon is held in storage in the bodies of living things.

When living things die, their bodies decompose and the carbon is returned to the cycle in inorganic form.

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Organic Carbon Storage

Exception: Organic carbon is stored for very long periods in bogs.

Very limited oxygen in bogs, therefore, plants and animals takes thousands of years to decompose.

Carbon locked away in organic form. Carbon in dead plant material is known as peat

25

Human Activity and Carbon Cycle

Modern times people have discovered fossil fuel deposits

Used them to supply our energy needs.

Humans have also affected the carbon cycle by cutting down forests.

26

Human Activity and Carbon Cycle

Carbon dioxide produced faster rate than nature can recycle it.

Fewer trees results in a reduction in photosynthesis.

Enhanced greenhouse effect where atmosphere is gradually heating up.

The gradual rise in temperature may have disastrous effect on ecosystems. Possible widespread extinction of plants and animals..