Cycling of MatterCarbon Cycle

Nitrogen Cycle

Ecosystems TEKS• TEK 7.5 B – Demonstrate and explain the cycling of

matter within living systems such as in the decay of biomass in a compost bin. • Biomass is the material that makes up living organisms.• Decomposition is when substances are broken down.

Decomposers are bacteria, fungi, earthworms, and dung beetles. • As material decomposes in a compost bin, heat, along

with other gases (CO2 & Nitrogen), are given off. Composting provides natural and organic fertilizer which is both healthy for the soil and environment. The decaying process releases energy and recycles biomass.• The Nitrogen, Carbon, and Water cycles demonstrate

and explain the cycling of matter within living systems.

• TEK 7.6 A – Identify that organic compounds contain carbon (C) and other elements such as hydrogen (H), oxygen(O), nitrogen (N), phosphorus(P), and sulfur (S). • Organic compounds are comprised of carbon and other

elements that are recycled due to chemical changes that rearrange the elements for the particular needs of living things. • Inorganic compounds rarely contain the element carbon

and are from nonliving things.

Ecosystems TEKS

Carbon Cycle• Carbon is one of the most important elements on Earth.• All living things have carbon in their cells. Organisms need

carbon to survive. • However, Earth only has a certain amount of carbon.

Living things are constantly being born and growing, so how do the increasing numbers of living things get the carbon they need?• Carbon (as well as other elements) moves between the

living and nonliving environment in cycles. • The Carbon Cycle allows this to happen.

Where does Carbon exist?• Atmosphere (air) as a gas called carbon dioxide.

• Biosphere (the living environment) in the cells of organisms.• Geosphere (Earth’s crust) in the rocks.• Hydrosphere (liquid Earth) dissolved in water.

Atmosphere• Oxygen (O2) makes up 20% of the atmosphere.• When carbon is attached to two oxygen molecules, it

becomes carbon dioxide (CO2), which is toxic or poisonous if animals or people breathe in too much of it. • Plants remove CO2 from the air during photosynthesis.

Biosphere• Carbon exists in the bodies of living things (plants, animals).• Plants get the carbon they need because they create their own sugar

molecules (glucose) through photosynthesis. • When animals eat plants, the animals get the carbon they need. • Carbon becomes part of the cells of consumers through the food they

eat. When animals eat other animals who ate plants, the carbon is passed along to them.

How does carbon get recycled into the atmosphere?

3 ways

• When plants perform photosynthesis, they release oxygen (O2) into the air. • Consumers breathe in and use this O2 as they break down the

sugars they eat. Animals then breathe out and give off CO2 into the air so the plants can use it again.• CO2 is returned to the atmosphere by respiration – when

animals breathe.

Respiration(Animals Breathing)

Decomposition (Decay)• When an organism dies, the tissues, including carbon, are

broken down by decomposers, releasing CO2.

• Burning wood or fossil fuels (oil, gas) releases large amounts of CO2 into the atmosphere. Because they are made from plants, they contain carbon, which is released as CO2. Cars and factories contribute a lot.• Combustion also happens in forest fires.

Combustion (Burning)

Carbon Cycle

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Cellular

Decomposition

Combustion

Carbon Cycle Video

https://youtu.be/vrDekmRbBVk

Nitrogen Cycle• Where does Nitrogen exist?• It is found in many places just like carbon, and it gets recycled to be reused through the Nitrogen Cycle.• Nitrogen is the main gas in the atmosphere, making up 78%.• However, Nitrogen is in a form that plants or animals can’t

use. It must first be changed with the help of bacteria in the soil and water into Nitrogen compounds that other living things can use.• Nitrogen fixation – the process that changes atmospheric

Nitrogen into Nitrogen compounds that are usable by living things.

78%

21%

1%

• 1. Lightning changes nitrogen gas in the atmosphere to nitrogen compounds that fall to the ground when it rains.

• 2. Nitrogen-fixing bacteria in the soil converts it to usable nitrogen compounds that plants can take in.

• 3. Animals eat the plants, getting the nitrogen compounds passed on to them.

• 4. When an organism dies, decomposers break down the tissues. As decomposition occurs, Nitrogen is given off as a gas and returned to the atmosphere. It is also returned through animal waste as fertilizer for new plants.

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