Question 1: The carbon cycle describes the process by which carbon atoms move through the Earth's atmosphere, biosphere, oceans, and geosphere. It involves processes such as photosynthesis, respiration, decomposition, and combustion.

Answer: The carbon cycle is the movement of carbon atoms through different parts of the Earth system, involving processes like photosynthesis, respiration, decomposition, and combustion.

Question 2: Define 'carbon fixation' in the context of the carbon cycle.

Answer: Carbon fixation is the process by which plants convert inorganic carbon dioxide from the atmosphere into organic compounds during photosynthesis.

Question 3: Which process releases carbon dioxide back into the atmosphere: photosynthesis or respiration?

Answer: Respiration

Question 4: Fill in the blank: The burning of fossil fuels is an example of 

Answer: See full answer key

Question 5: Explain how deforestation affects the carbon cycle.

Answer: Deforestation reduces the number of trees available to absorb carbon dioxide during photosynthesis, leading to higher atmospheric CO2 levels. It also releases stored carbon in trees when they are burned or decay, disrupting the balance of the carbon cycle and contributing to climate change.

Question 6: Calculate the amount of carbon dioxide (in grams) released when 10 kg of fossil fuels are combusted, assuming the combustion releases all stored carbon as CO2. (Atomic mass of Carbon = 12 g/mol, Molecular mass of CO2 = 44 g/mol)

Answer: First, calculate moles of carbon: 10,000 g / 12 g/mol = 833.33 mol. Since each mol of carbon forms 1 mol of CO2, total CO2 mass = 833.33 mol * 44 g/mol = 36,666.52 g.

Question 7: Identify two ways in which humans can reduce their impact on the carbon cycle.

Answer: Reducing fossil fuel use by switching to renewable energy sources and increasing reforestation efforts.

Question 8: Describe a practical method that scientists could use to measure the amount of carbon stored in soil samples.

Answer: Scientists can collect soil samples and analyse them using techniques such as dry combustion with a CHNS analyser or infrared spectroscopy to determine the amount of organic carbon present, providing an estimate of soil carbon storage.