Question

In the temperate zone, is the atmospheric concentration of carbon dioxide higher during the day or night? Why?

Short answer

Explain your answer. Answer: The atmospheric concentration of carbon dioxide is higher during the night in the temperate zone. This is because photosynthesis, which consumes CO2, slows down or stops at night due to the absence of sunlight, while respiration, which releases CO2, continues throughout the night. As a result, there is a net increase in atmospheric CO2 concentration during the night.

Step-by-step solution

Understand photosynthesis and respiration in plants

Photosynthesis is the process by which plants convert light energy from the sun into chemical energy in the form of glucose. During this process, plants absorb carbon dioxide (CO2) from the atmosphere and release oxygen (O2). On the other hand, respiration is the process where plants break down the stored glucose to release energy. During respiration, plants consume oxygen and release carbon dioxide. Photosynthesis primarily occurs during daytime when sunlight is available, while respiration occurs throughout the day and night.

Analyze CO2 concentration during the day

During the daytime, photosynthesis is the dominant process in plants due to the availability of sunlight. As a result, plants consume more carbon dioxide from the atmosphere and release oxygen. This leads to a decrease in the overall atmospheric CO2 concentration during the day.

Analyze CO2 concentration during the night

At night, there is no sunlight available for photosynthesis. Thus, photosynthesis slows down or stops in most plants. However, respiration continues to occur throughout the night as plants still need to break down glucose to release energy. During respiration, plants will consume oxygen and release carbon dioxide into the atmosphere. Therefore, the atmospheric concentration of CO2 increases during the night.

Conclusion

In the temperate zone, the atmospheric concentration of carbon dioxide is higher during the night. The main reason for this is the absence of sunlight at night, which slows down or stops photosynthesis in plants. As a result, plants consume less CO2 from the atmosphere, while still releasing CO2 through respiration, leading to an overall increase in atmospheric CO2 concentration.

Key concepts

Photosynthesis

Plants possess an incredible ability to convert light from the sun into energy, through a process known as photosynthesis. This chemical reaction primarily occurs in chloroplasts found in plant cells. During photosynthesis, plants draw in carbon dioxide ( CO_2 ) from the air and utilize sunlight to transform it into glucose, a sugar molecule used to fuel their growth and metabolism. Oxygen ( O_2 ) is released as a byproduct of this transformation. The presence of sunlight is crucial for photosynthesis, hence it primarily occurs during the daytime.

Key aspects of photosynthesis include:

• Utilizes sunlight as an energy source.
• Absorbs CO_2 and releases O_2 .
• Makes glucose which is vital for plant growth.

Understanding photosynthesis is key to recognizing why carbon dioxide levels may vary between day and night. During periods without sunlight, especially at night, this vital process comes to a halt, affecting atmospheric CO_2 levels.

Respiration

Unlike photosynthesis, respiration occurs in plants continuously, day and night. This process is crucial for the survival of plants as it allows them to convert the stored energy in glucose into usable energy needed for growth and maintenance. During respiration, glucose reacts with oxygen to produce carbon dioxide ( CO_2 ), water, and energy in the form of adenosine triphosphate (ATP).

Respiration's key points include:

• Occurs continuously, without needing sunlight.
• Releases CO_2 into the atmosphere.
• Provides energy for cellular activities in plants.

Since respiration continues at night while photosynthesis halts, there's a net increase in carbon dioxide output from plants during nighttime. This process is partly why carbon dioxide concentrations rise in the atmosphere after dark in areas with dense vegetation.

Diurnal Variation

The concept of diurnal variation refers to the fluctuations in natural phenomena that follow a daily cycle, influenced by the presence or absence of sunlight. In terms of carbon dioxide ( CO_2 ) concentration in the temperate zone, diurnal variation is observable in the contrasting roles of photosynthesis and respiration over a 24-hour period.

During the day:

• Photosynthesis prevails, resulting in increased CO_2 uptake by plants.
• Leads to a reduction in atmospheric CO_2 levels.

At night:

• Photosynthesis stops due to lack of sunlight.
• Respiration becomes predominant, releasing more CO_2 into the air.
• Results in a rise in atmospheric CO_2 concentration.

Understanding diurnal variation provides valuable insight into how daily cycles impact environmental parameters, specifically carbon dioxide levels, which are influenced by natural plant processes. This concept helps explain why you might detect higher CO_2 concentrations at night compared to daytime in many environments.