Why do Plants Release Carbon Dioxide at Night?

Introduction

Photosynthesis is one of the essential processes that plants undergo to create food and oxygen. It is the process of converting carbon dioxide $\mathrm{(CO_2)}$ and water $\mathrm{(H_2O)}$ into glucose $\mathrm{(C_6H_{12}O_6)}$ and oxygen $\mathrm{(O_2)}$. During the day, plants take in carbon dioxide from the air and use it to create energy through photosynthesis.

However, at night, plants continue to respire, which means they release carbon dioxide instead of taking it in. This phenomenon raises the question, why do plants release carbon dioxide at night? In this tutorial, we will explore the reasons behind this occurrence and its significance for plants.

Respiration

Before delving into the reasons behind plants releasing carbon dioxide at night, we must understand the significance of respiration in plants. Respiration is a process that occurs in all living organisms, including plants, animals, and microorganisms.

It is the process of converting glucose into energy by breaking down the molecules through a series of chemical reactions. This process occurs in the mitochondria of the cell, which are the energy-producing organelles of the cell.

$$\mathrm{Glucose + Oxygen\:\rightarrow\:Carbon \:dioxide + Water}$$

$$\mathrm{C_6H_{12}O_6 + 6O_2 \:\rightarrow\:6CO_2 + 6H_2O}$$

Respiration in plants is crucial because it provides the energy required for various processes, including cell division, growth, and reproduction. Additionally, respiration in plants also helps in the breakdown of organic matter in the soil and aids in nutrient uptake. Without respiration, plants would not be able to survive and carry out their vital functions.

What Happens to Carbon Dioxide During the Day?

During the day, plants release oxygen into the air through photosynthesis and take in carbon dioxide from the atmosphere. Carbon dioxide is necessary for photosynthesis as it serves as a source of carbon for the plant to produce glucose.

However, the amount of carbon dioxide released by plants during the day is much less compared to the amount released at night through respiration. The carbon dioxide released by plants during the day is quickly taken up by other plants, algae, and other organisms for photosynthesis, contributing to the global carbon cycle.

Additionally, carbon dioxide released during the day can also be absorbed by oceans, where it is used by marine plants and organisms. Overall, the amount of carbon dioxide released by plants during the day is relatively small compared to the amount absorbed through photosynthesis, making photosynthesis a vital process in reducing carbon dioxide levels in the atmosphere.

Why Carbon Dioxide Is Released at Night?

There are several reasons behind plants releasing carbon dioxide at night. The primary reason for this phenomenon is the absence of sunlight. During the day, plants take in carbon dioxide and use it to create glucose through photosynthesis. However, at night, there is no sunlight available for photosynthesis to occur. Therefore, the plant's cells switch to cellular respiration to produce energy.

Another reason for the release of carbon dioxide at night is that plants continue to carry out metabolic processes during this time. Even though there is no sunlight available, plants continue to use energy to carry out metabolic processes such as repairing damaged tissue and producing new cells. These processes require energy, which is provided through respiration.

Additionally, the release of carbon dioxide at night is also affected by temperature. During the day, when temperatures are high, plants close their stomata to conserve water. As one of the functions of stomata is gaseous exchange, when the stomata close there is an excess buildup of carbon dioxide (left after photosynthesis) which gets accumulated during the day. This is also released at night when the stomata open.

This excess carbon dioxide along with the carbon dioxide released through respiration increases the total percentage of carbon dioxide released during the night.

Humidity is another factor that affects the release of carbon dioxide at night. When humidity is high, plants transpire less, leading to less water loss through their leaves. This allows plants to keep their stomata open for longer periods, facilitating the exchange of gases such as carbon dioxide.

Conclusion

In conclusion, respiration is a crucial process that occurs in all living organisms, including plants. It is the process of converting glucose into energy through a series of chemical reactions. At night, plants release carbon dioxide instead of taking it in due to the absence of sunlight and the continuation of metabolic processes.

Temperature and humidity also play a role in the release of carbon dioxide at night. Understanding the reasons behind this occurrence is vital for researchers and scientists studying plant physiology and the global carbon cycle.

FAQs

Q1. How much carbon dioxide do plants release at night?

Ans. Plants release varying amounts of carbon dioxide at night depending on their size, age, and metabolic activity. However, on average, plants can release between 10 and 100 times more carbon dioxide at night than during the day.

Q2. Can plants continue to grow in the absence of sunlight?

Ans. Plants require sunlight for photosynthesis, which is essential for their growth. However, some plants, such as those that grow in caves or other low light conditions, have adapted to low light levels and can still carry out photosynthesis and grow. These plants rely on other sources of energy, such as chemical energy, to carry out photosynthesis.

Q3. Can high humidity affect plant growth?

Ans. High humidity can affect plant growth by reducing the amount of water plants lose through their leaves. When humidity is high, plants transpire less, leading to less water loss and less uptake of nutrients. This can affect the growth and development of the plant.

Q4. How does temperature affect plant respiration?

Ans. Temperature affects plant respiration by influencing the rate at which chemical reactions occur. At optimum temperature the rate of respiration will be high. At higher temperature rate of respiration decreases, due to low availability of oxygen. At lower temperatures, the rate of respiration slows down due to freezing of plant tissues.

Q5. How do plants contribute to the global carbon cycle?

Ans. Plants contribute to the global carbon cycle by absorbing carbon dioxide from the atmosphere during photosynthesis and converting it into organic compounds, such as glucose, which are used for energy and growth. They release oxygen as a byproduct, which is essential for respiration in animals and other organisms. When plants die or shed leaves, the carbon they have accumulated is returned to the atmosphere or the soil, where it may be stored for long periods of time or released through decomposition or combustion.