Tutor profile: Elizabeth A.
Subject: Environmental Science
Compare the carbon cycle and the nitrogen cycle.
Like all the biogeochemical cycles, the carbon and nitrogen cycles depend on the power of the sun for their ultimate energy source. Both cycles use oxygen as a combining element to create various compounds. Both cycles have a significant role in the atmosphere, the soil, and the hydrosphere. Both of these cycles have a tremendous influence on living organisms: all life on Earth is carbon-based, and all life requires nitrogen-based proteins and nucleic acids. Both of these cycles have an impact on global climate change: the carbon cycle includes carbon dioxide, a well known greenhouse gas. Nitrous oxide (part of the nitrogen cycle) is also a greenhouse gas, but less famous.
What is the Haber Process and what does it have to do with World War II?
The Haber Process is also called the Haber-Bosch process sometimes. It is named after the chemists who invented it in the early 1900's. The chemical reaction seems simple: N2 + 3 H2 --> 2NH3. The tricky part is that this reaction does not occur under normal conditions, and the chemists had to figure out how to use a catalyst with high temperature and high pressure. Do you know what a catalyst is? It is a substance, in this case iron metal, that increases the rate of a chemical reaction without being changed in the process. Haber and Bosch won the Nobel prize for this important work. We still use this chemical reaction today to make fertilizer for plants. Germany in World War II needed a way to make bombs and explosives, and the Allies had blocked the import of such materials. The Germans used the Haber-Bosch process to make their own explosives for the war.
Who is Gregor Mendel and why is he important in Biology?
Gregor Mendel lived in the 1800's and grew pea plants (among many other things). The interesting part and why he is important is because he paid attention to the traits (characteristics) of the pea plants that he grew. Peas can be carefully pollinated (crossed) with other specific pea plants to produce new seeds which grow into new pea plants, and Gregor was very good at doing this. He noticed that tall plants crossed with tall plants produced more tall plants. Seems easy, right? He also noticed that short plants crossed with short plants produced more short plants. But then when he crossed a tall pea plant with a short pea plant, he obtained seeds that produced some tall and some short plants in a very specific ratio. Every time. Gregor was smart enough to figure out what was going on, and he came up with the idea of dominant and recessive genes. He wrote down his experiments and his results. This was the foundation for what we now call genetics, a very important part of Biology.
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