Which of the following adds/add carbon dioxide to the carbon cycle on the planet Earth? 1. Volcanic action 2. Respiration 3. Photosynthesis 4. Decay of organic matter Select the correct answer using the code given below.

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Q: 19 (IAS/2014)

Which of the following adds/add carbon dioxide to the carbon cycle on the planet Earth?
1. Volcanic action
2. Respiration
3. Photosynthesis
4. Decay of organic matter
Select the correct answer using the code given below.

question_subject: 

Science

question_exam: 

IAS

stats: 

0,214,58,9,9,214,40

keywords: 

{'carbon cycle': [0, 0, 0, 2], 'carbon dioxide': [2, 0, 5, 6], 'photosynthesis': [20, 0, 4, 11], 'organic matter': [1, 0, 0, 0], 'respiration': [2, 0, 1, 3], 'decay': [0, 0, 0, 4], 'planet earth': [0, 0, 4, 6], 'adds': [0, 0, 0, 2], 'volcanic action': [0, 0, 0, 2]}

Option 1 suggests that volcanic action and photosynthesis add carbon dioxide to the carbon cycle. This is partly true as volcanic action does release CO2. However, photosynthesis absorbs CO2 and thus does not `add` it to the carbon cycle.

Option 2 posits that respiration is the only source of CO2 in the carbon cycle. While it is correct that organisms release CO2 through respiration, it`s not the only source.

Option 3 is the correct answer. Volcanic action, respiration and decay of organic matter all release CO2 into the atmosphere. Volcanoes release CO2 trapped in the earth`s mantle, organisms release CO2 through respiration and as organic matter decays, it also releases CO2.

Option 4 incorrectly includes photosynthesis as a process that adds carbon dioxide to the carbon cycle. It should be noted that photosynthesis is a process taken by plants and algae to convert CO2 and sunlight into oxygen and glucose, thus reducing the amount of CO2 in the atmosphere.