Problem 7 - Biology

Question

Which of the following processes increase(s) the amount of atmospheric carbon in the carbon cycle? (a) photosynthesis (b) cellular respiration (c) combustion (d) a and \(c\) (e) b and \(c\)

Step-by-Step Solution

Answer

Cellular respiration and combustion (option e) increase atmospheric carbon.

Step 1: Understanding the Question

The question asks about which processes contribute to increasing the amount of atmospheric carbon. The carbon cycle involves several processes that add and remove carbon to and from the atmosphere.

Step 2: Evaluate Photosynthesis

Photosynthesis is the process by which plants, algae, and some bacteria use sunlight to convert carbon dioxide and water into glucose and oxygen. This process reduces atmospheric carbon as it takes in carbon dioxide.

Step 3: Evaluate Cellular Respiration

Cellular respiration is the process by which cells convert glucose and oxygen into energy, releasing carbon dioxide and water as by-products. This process increases atmospheric carbon because it emits carbon dioxide.

Step 4: Evaluate Combustion

Combustion is a chemical process in which a substance reacts with oxygen to give off heat and carbon dioxide. This process increases atmospheric carbon as it releases carbon dioxide into the atmosphere.

Step 5: Determine the Correct Combination

Based on the analysis, cellular respiration and combustion both increase atmospheric carbon. Photosynthesis decreases it. Therefore, the correct processes that increase atmospheric carbon are cellular respiration and combustion.

Key Concepts

Photosynthesis

Plants, algae, and certain bacteria perform photosynthesis, a crucial process in the carbon cycle. During photosynthesis, these organisms absorb carbon dioxide ( CO_2 ) from the atmosphere and use sunlight to convert it into glucose ( C_6H_{12}O_6 ) and oxygen ( O_2 ). This process plays a vital role in removing carbon dioxide from the air.

• Photosynthesis occurs mainly in the leaves of plants, where chlorophyll captures sunlight.
• The overall equation for photosynthesis can be written as: 6 CO_2 + 6 H_2O + light energy ightarrow C_6H_{12}O_6 + 6 O_2 .
• The glucose produced is used as food by the plant, providing energy for growth and development.

By reducing atmospheric carbon dioxide, photosynthesis acts as a natural cleanser for the air, balancing the amounts of carbon in our planet's ecosystem.

Cellular Respiration

Cellular respiration is how living organisms, including humans, convert glucose into energy. This process happens in the cells and releases carbon dioxide back into the atmosphere, thus increasing the level of atmospheric carbon.

• Glucose and oxygen are used to produce energy, with carbon dioxide and water being the by-products.
• The chemical equation for cellular respiration is essentially the reverse of photosynthesis: C_6H_{12}O_6 + 6 O_2 ightarrow 6 CO_2 + 6 H_2O + energy .
• This process occurs in the mitochondria of cells, known as the powerhouses.

The energy produced by cellular respiration is essential for various functions, including cellular repair, growth, and maintaining bodily functions. While necessary for life, cellular respiration contributes to an increase in carbon dioxide in the atmosphere.

Carbon Emissions

Carbon emissions refer to the release of carbon, especially carbon dioxide, into the atmosphere from various sources. These increase atmospheric carbon levels and are a major component of the carbon cycle.

• Combustion is a leading source of carbon emissions, occurring when fossil fuels like coal, oil, and natural gas are burned for energy.
• Other sources include deforestation, as trees which store carbon are cut down, and industrial activities.
• Carbon emissions lead to environmental issues such as air pollution and climate change.

Efforts to reduce carbon emissions involve shifting to renewable energy sources, enhancing energy efficiency, and reforesting areas. By managing carbon emissions, humans aim to reduce their impact on Earth's climate and promote sustainable living.