Teaching the Carbon Cycle

The carbon cycle is the process by which carbon enters and exits the earth’s atmosphere. Carbon, in the form of carbon dioxide, and along with other gases, acts as a warming layer for Earth. Without this layer of gases, the Earth would be too cold to sustain life. There are many carbon cycle models and carbon cycle demonstration kits available to assist in the explanation of this process. Below is a basic explanation of the carbon cycle.

The Carbon Cycle

Carbon is released into the environment in many ways. Animals and plants respire, releasing carbon dioxide into the atmosphere. Animals release solid waste products into the soil and water. Also, leaves, roots, wood and dead animals decay. Finally, the burning of fossil fuels and wood release stored carbon into the atmosphere.

The carbon that is released into the environment, is used by many plants and animals. This is the part of the carbon cycle that removes carbon from the atmosphere. Plants and algae take in carbon dioxide during photosynthesis. Many sea creatures take in carbon when making shells and bones. When these animals die and sink to the ocean floor, this carbon is stored for some time.

The Ocean’s Role

The majority of photosynthesis occurs in the oceans by algae and phytoplankton. Also, due to the large surface area of the oceans , carbon dioxide diffuses in and out in an attempt to equalize.

The Nitrogen Cycle

Nitrogen is found throughout the soils and atmosphere in many different, organic and inorganic, forms. The Nitrogen Cycle is the process by which atmospheric nitrogen enters the soil, is transformed by microbes, and re-enters the atmosphere (volatilization) and plants (assimilation).

How Does Nitrogen Enter the Soil?

Before nitrogen can be used by plants, it must enter the soil. Atmospheric nitrogen is forced to the ground by rainfall. Also, urine, solid and liquid waste from living organisms and living organisms that have died are deomposed by bacteria and fungi. The nitrogen from these sources then enter the soil. Commercial fertilizers are another source of nitrogen.

What Happens to Nitrogen in the Soil?

Plants cannot use organic nitrogen. Bacteria and fungi are needed to transform this unusable organic nitrogen into a usable form. Although most nitrogen fixation is completed by bacteria, some is accomplished through lightning strikes. Since ammonia is fatal to most plants, bacteria convert this ammonia (NH4) into nitrates (NO3) and nitrites (NO2). At this time, the nitrogen can be assimilated into the plant, leached into the ground water or be transformed into a gas and re-enter the air.

In very wet soils, the oxygen content is low. The bacteria in these soils take the oxygen out of the nitrates (NO3) and produce nitrogen gas. This process is call denitrification. Through a process called volatilization, the gas re-enters the atmosphere.

Owl Pellets and Owl Digestion

owlDissecting owl pellets is a fun and educational method of analyzing predator/prey relationships and for learning basic dissection techniques.

What is an Owl Pellet?

An owl pellet is the portion of an owl’s prey that has not been digested. Owl’s swallow their prey whole (they don’t have teeth to chew) and the feather’s, fur, bones and other undigestible parts are regurgitated by the owl.

How Does the Owl Pellet Form?

When the prey is swallowed, it travels through the esophagus and into the first part of the stomach, the proventriculus. Unlike other birds, the owl does not have a crop to store the food. As a result, the prey enters directly into the digestive tract. This part of the stomach has enzymes and acids (like our stomachs) to aid in digestion. From the proventriculus, the food travels to the second part of the stomach, the gizzard. The gizzard is a muscular organ that grinds the food and “filters” undigestible parts from traveling into the intestines.

The pellet is formed from the hair, bones or feathers that are left in the gizzard. The pellet will take several hours to form and several more before it is regurgitated. The owl cannot eat again until this pellet is expelled.

Does the Regurgitation of the Pellet Benefit the Owl?

Yes. Many scientists believe that this regurgitation of the pellet keeps the upper digestive tract clean.

Hydrolysis – The Splitting of Water

See the Oxygen molecules bubble and the indicator turn pink

See the Oxygen molecules bubble and the indicator turn pink

Hydrolysis Water Splitting

Using a 9V battery, 2 electrodes and small gauge wire, you can split water into its component parts. This process is called hydrolysis. We add a small amount of salt to increase the conductivity of the water and an acid/base indicator to visualize the reaction.

The chemical formula of water is H2O. When the electrical current, produced by the battery, passes through the water, the water will split and the two electrodes will bubble. Hydrogen will appear at the cathode and the oxygen at the anode. The acid base indicator around the cathode will turn blue (because the free OH molecules raise the pH) and the area around the anode will turn pink (because the free hydrogen molecules lower the pH).

Looking at the formula for water, there are twice as many hydrogen atoms as oxygen. When hydrolysis occurs, twice as many hydrogen bubbles will be released as oxygen. You can visually see extra bubbles at the point where hydrogen is being released.

Hydrolysis experiments can be quantitative (how much hydrogen and oxygen are released?) or qualitative (can I visually see the reaction taking place?)