Question

read the passage and answer the following question(s). carbon cycle model the model shown below represents the transfer of carbon through the atmosphere, soil, and biosphere. carbon cycle model which label would best complete the model to represent a human activity that has increased over the past century to result in increased concentrations of carbon dioxide in earths atmosphere? a. label w, w = combustion b. label y, y = respiration c. label w, w = respiration d. label y, y = combustion

Explanation:

• Combustion (Label W): When fossil fuels (which are rich in carbon) are burned (combustion), carbon dioxide ($CO_2$) is released into the atmosphere. Over the past century, the extensive use of fossil fuels (a human activity) has led to a significant increase in the burning of these fuels. As a result, a large amount of carbon dioxide that was previously trapped in fossil fuels is now being emitted into the atmosphere, contributing to the rise in atmospheric $CO_2$ levels.
• Respiration (Label X): This is a natural process (not primarily driven by human activity in the context of the significant increase over the past century). Both plants and animals respire, taking in oxygen and releasing carbon dioxide. But the rate of respiration has not seen a human - induced exponential increase like fossil fuel combustion.
• Respiration (Label Y): Similar to label X, this represents the natural respiration process of organisms. It is a part of the normal carbon cycle and not the main factor for the increased $CO_2$ due to human activities over the past century.
• Combustion (Label Y): Incorrect as label Y is respiration (for animals, it is their normal metabolic process of releasing $CO_2$ after breaking down organic matter for energy).

Answer:

A. label W, W = combustion