Carbon cycle assessment

Volcanic eruptions add carbon dioxide to the atmosphere. Which of the following also adds carbon dioxide directly to the atmosphere?

• A. burning a forest
• B. forming fossil fuels (when plants were turned into coal, oil, and gas)
• C. evaporation of a puddle
• D. erosion of igneous rocks

Which of the following are mainly cycled through the processes of photosynthesis and cellular respiration?

• A. carbon and sulfur
• B. carbon and oxygen
• C. nitrogen and sulfur
• D. nitrogen and oxygen

Carbon fixation is an important part of the carbon cycle. Carbon fixation is the conversion of carbon dioxide into organic compounds such as glucose. Which of the following organisms cannot fix carbon?

• green algae
• mushrooms
• grass
• oak trees

Which of the following processes removes carbon from the air and uses it to make organic compounds?

• A. combustion
• B. decomposition
• C. photosynthesis
• D. respiration

The diagram below shows a chloroplast and some of the components of the reactions that occur in chloroplasts. Which of the following is a product of the reactions that take place in a chloroplast?

• A. hydrogen gas
• B. nitrate
• C. oxygen gas
• D. protein

Which statement is an example of how carbon moves through a food chain as part of the carbon cycle?

• Producers release carbon dioxide, and consumers take it in.
• Producers take in carbon dioxide, and consumers release it.
• Producers take in carbon from the soil, and they release it when they decompose.
• Producers release carbon into the soil, and consumers take it in from the soil.

A composter speeds up the decomposition of dead plant material. The illustration below shows a person putting plant material into a composter. Which of the following is one result of the decomposition of the plant material?

• A. Photosynthesis produces starches.
• B. A mixture of water and salt is created.
• C. All bacteria and other microorganisms die.
• D. Carbon dioxide is released to the atmosphere.

Earth’s atmosphere is 20.9% molecular oxygen (O2). Which process provides most of the oxygen in the atmosphere?

• A. cellular respiration
• B. osmosis
• C. photosynthesis
• D. transpiration

Scientists use satellite data to produce images such as the one below, showing the density of plants across Earth’s different land areas. Scientists study these images to determine how plant density changes during a year. They can then use this information to help predict carbon dioxide concentrations in the atmosphere in different locations and at different times of the year. Which of the following best explains why scientists can predict carbon dioxide concentrations from plant density data?

• A. Plants add carbon dioxide to the atmosphere during germination.
• B. Plants add carbon dioxide to the atmosphere during transpiration.
• C. Plants remove carbon dioxide from the atmosphere during photosynthesis.
• D. Plants remove carbon dioxide from the atmosphere during cellular respiration.

Which of the following types of organisms perform BOTH cellular respiration AND photosynthesis?

• birds
• plants
• insects
• fungi