B.13C_Carbon_onlevel – 02

A student group was standing in front of a dinosaur exhibit at the Natural Science Museum. Their museum guide held up a small piece of natural chalk and asked if anyone could explain how the piece of chalk could contain carbon that was exhaled by a dinosaur. The students were intrigued by the question and began discussing the facts needed to answer the question. First, they must find out where chalk is found in nature. Next, they must investigate the processes that would provide a path for carbon in the atmosphere to become carbon in the chalk.

The museum guide gives the students a hint by telling them that natural chalk is made of a chemical compound called calcium carbonate. Carbonate contains carbon, so the students realize that this is an important fact about chalk. Carbon is an essential element in all organisms. Plants need carbon to grow and reproduce. Animals obtain carbon by eating plants or other animals. Carbon compounds are a source of energy for living things. The carbon in organisms is the basis of all the organic molecules in their structure.

Chalk is not a living thing and calcium carbonate is not an organic molecule, so the students search for more facts. The museum guide stated that all the answers can be found in the museum. In the shell exhibit, the students were told that shells of marine animals are made of calcium carbonate. This fact provides an organic connection to the chalk, since marine animals are living things.

The students turn their attention to the carbon in the atmosphere. The carbon cycle moves carbon from the atmosphere to organisms and back to the atmosphere. The carbon cycle is a biogeochemical cycle in which atoms move between abiotic factors and biotic factors. Abiotic factors in the carbon cycle are the atmosphere, bodies of water, decomposed organic matter in soil called humus, and rock formations. Biotic factors are all living things.