How do green plants respire in the absence of sunlight?
Plants respire at all times, whether or not there is sunlight present. Plants respire similarly to other aerobic organisms. That is, they consume oxygen and release carbon dioxide. This is the process of cellular respiration and can be summarized by the following balanced chemical equation:
`C_6H_12O_6 + 6O_2 -> 6CO_2 + 6H_2O + ATP`
Here, the glucose breaks down in the presence of oxygen, and carbon dioxide, water and ATP molecules (energy molecules) are generated.
During the sunlight hours, the green plants carry out the process of photosynthesis, in which they consume carbon dioxide and water and generate oxygen and glucose.
Thus, the two processes (photosynthesis and respiration) consume the products of each other.
The exchange of gases, in the case of plants, is done by the leaves through the process of diffusion. In this process, gases move across a gradient: from higher to lower concentration. Leaves provide sufficient surface area and stomata control the gaseous exchange with the environment. When plants respire, oxygen is taken in and carbon dioxide is released to the atmosphere.
Hope this helps.