Question

2.4 review

1. identify which cycle most relies on the processes of photosynthesis and cellular respiration?

a. carbon cycle c. nitrogen cycle
b. phosphorus cycle d. water cycle

1. identify which of these processes are carried out by anaerobic bacteria? select all correct answers.

a. decomposition c. denitrification
b. transpiration d. nitrification

1. analyze consider the cycles modeled in figures 2 - 13, 2 - 14, 2 - 15, and 2 - 16 that show what happens to a water molecule, a carbon atom, a nitrogen atom, and a phosphorus atom, respectively. describe two ways the water cycle is different from the other cycles.
2. design use figure 2 - 13 to make a simple model that follows an oxygen atom as it cycles through any two of these spheres: atmosphere, biosphere, hydrosphere.

Explanation:

1. Photosynthesis and cellular respiration are key processes in the carbon cycle. Plants take in carbon - dioxide during photosynthesis and release it during cellular respiration.
2. Anaerobic bacteria carry out decomposition and denitrification. Decomposition breaks down organic matter and denitrification converts nitrates to nitrogen gas. Transpiration is a plant - related process and nitrification is mainly carried out by aerobic bacteria.
3. The water cycle involves the movement of water in different states (solid, liquid, gas) and is driven by evaporation, condensation, and precipitation. It is different from other cycles as water is a compound while carbon, nitrogen, and phosphorus are elements. Also, water exists in large amounts in the hydrosphere and has a unique phase - change cycle.
4. For example, an oxygen atom in a water molecule in the hydrosphere can evaporate into the atmosphere. Then, the water vapor can condense and fall as precipitation back into the biosphere when it is taken up by plants during photosynthesis.

Answer:

1. A. carbon cycle
2. A. decomposition, C. denitrification
3. The water cycle involves a compound (water) while others involve elements. Water has a unique phase - change cycle driven by evaporation, condensation, and precipitation.
4. An oxygen atom in a water molecule in the hydrosphere evaporates into the atmosphere. Then it condenses and falls as precipitation into the biosphere where it is taken up by plants during photosynthesis.