All living organisms, containing plants, get the energy necessary for their survival from a series of chemical reactions termed respiration. The process of respiration needs glucose to start the reactions which are changed into energy and later produce carbon dioxide and water as by-products.
The method by which cells get chemical energy by the consumption of oxygen and the liberating of carbon dioxide is called respiration. In order to carry on respiration, plant cells require oxygen and a means of disposing of carbon dioxide just as animal cells do. In plants, every part such as root, stem executes respiration as plants do not possess any particular organs like animals for the exchange of gases.
The method of respiration is written as:
Oxygen + Glucose → Water + Carbon Dioxide with Energy
We can conclude the same from the equation above as well that respiration uses oxygen and to produce carbon dioxide.
This is the main question when we think about plant respiration. As plants do not have any specialized organs like lungs so we can say that plants do not breathe rather they respire. Plants respire with the help of lenticels and stomata (exist in stems and leaves individually) which carry out the function of the gaseous exchange.
Plant respiration happens 24 hours a day, but night respiration is more obvious as the photosynthesis process finishes. During the night, it is very vital that the temperature is much cooler as compared to the daytime because plants can undergo stress. Imagine a marathon runner. The runner breathes at higher rates than an individual standing still; so, a runner’s amount of respiration is greater and the temperature of the body rises. The same principle relates to plants, as the temperature at night rises, the respiration rate increases, and similar temperature increases. This action would result in flower damage and also in plant poor growth.
In plants, respiration occurs with the help of roots. In soil oxygenated air is already present in spaces between soil particles. This oxygen is then absorbed into the roots with the help of root hair present on the roots. The hairs of the roots are in straight contact with them. In fact, root hair is a lateral tubular outgrowth of the external epidermal cells of a root. The oxygen present among the soil particles diffuses into the root hairs. From root hairs, oxygen is transported to all the parts of roots for respiration. During the respiration process, oxygen is transformed into carbon dioxide gas which is spread in the opposite direction i.e. out of the roots by the same root hairs which complete the respiration process of roots.
If a potted plant is watered over for a long time, then the plant can ultimately die. This is due to too much water exorcizing all the air from in between the soil particles. Because of this, oxygen is not free to the roots for aerobic respiration. In these states, the roots of plants respire anaerobically making alcohol. This can kill the plant. Germinating seeds during the early stage respire anaerobically as they have a seed coat that does not permit the oxygen to enter through it.
Respiration in plants occurs throughout the day and night thereby carbon dioxide is formed. Though, during the day, the total of carbon dioxide CO2 released is insignificant compared to the volume of oxygen made as a result of photosynthesis. Therefore, one should not sleep underneath a tree at night.
In the plants taking herbaceous stem exchange of gases occurs through stomata and the carbon dioxide CO2 formed during the process that gets diffused into the air with the help of stomata only. While in the plants having hard and woody stems the exchange of gases occurs through lenticels. Lenticels are usually loosely packed dead cells that are present as tiny pores on the bark of woody plants. These allow oxygen to pass to the intercellular spaces of the inside of tissues and carbon dioxide (CO2) to be liberated into the atmosphere by the phenomena of diffusion which completes the process of respiration in stems.
In leaves, the exchange of respiratory gases occurs through very small pores called stomata. The stomata are present in big numbers on the lower side of the leaves of the plant. Every stoma has a tiny pore at its centre which is enclosed and regulated by two kidney-shaped cells known as guard cells. When the stoma opens the exchange of gases occurs between the atmosphere and interior of the leaf by the method of diffusion and that completes the process of respiration in leaves.
There are two kinds of respiration that we categorize on the basis of the absence or presence of oxygen:
The respiration that occurs in the presence of oxygen is named aerobic respiration due to ‘air’ which has oxygen. Aerobic respiration contains the utilization of oxygen for the breaking of chemical bonds in glucose to liberate energy in high volumes. It is the central source of energy for plants. Animals and plants that use oxygen for respiration are aerobes. Most animals have aerobic respiration.
C6H12O6 +6O2 ⟶ 6CO2 + 6H2O + Energy
All the organisms that gain energy by aerobic respiration cannot exist without oxygen. This is due to no oxygen there; they cannot get energy from the food which they consume. Aerobic respiration takes more energy because a complete breaking of glucose takes place during respiration with the use of oxygen.
The respiration that occurs in the absence of oxygen is known as anaerobic respiration. In this process, the incomplete oxidation of food substances is being made by carbon dioxide CO2, and alcohol(OH). Besides this other organic matter such as citric acid, oxalic acid, lactic acid, etc are also produced.
This process is also called intramolecular respiration. Anaerobic respiration occurs in organisms like yeast, certain bacteria, and parasitic worms. The animals and plants that can exist and gain energy even in the lack of oxygen are called Anaerobic.
Glucose ⟶ Alcohol + CO2 + (Energy)
Yeast is known to be a single-celled fungus. In yeast, a single cell signifies the whole organism. A very low volume of energy is liberated in this process. Yeast respires anaerobically and all through this process, yeast transforms glucose into alcohol. So it is used to make alcohol, bread, etc.
Anaerobic respiration yields much less energy due to the only partial breakdown of glucose happening in anaerobic respiration in the absence of oxygen. All the organisms which gain energy by anaerobic respiration can exist without oxygen.
For instance, yeast is an organism that can exist without the oxygen of air as it obtains energy by the method of anaerobic respiration. Yeast can live in the absence of oxygen.
1. What are the elements needed for respiration in plants?
Plants need oxygen for respiration to occur and release carbon dioxide. Plants do not have special organs for the gaseous exchange but for this purpose, they have stomata and lenticels. But the interesting part is that plants might get along without the respiratory system. One, because there is very little exchange of gases between two plants. Second, since roots, leaves, and stems respire at rates much lower than animals, the demand for gas exchange is very low. Only during photosynthesis do plants need great amounts of gases as leaves are well adapted to take care of their own needs during this period.
2. Does respiration occur only during the day?
Respiration in plants is a continuous process that takes place throughout the day and even at night. In the morning, all the leaves make glucose with the help of carbon dioxide and water. The carbon dioxide produced then reaches empty spaces within the leaves and simultaneously photosynthesis begins. Carbon dioxide is released at a negligible amount as compared to the amount of oxygen released during photosynthesis in the day. This is the reason why it is advisable for people not to sleep under a tree at night.
3. What are the similarities and differences between Aerobic and Anaerobic Respiration?
Both Aerobic and Anaerobic Respiration processes use glucose as the starting molecule which is known as the substrate. Food is oxidized in both and energy is further released. ATP is produced through both Aerobic and Anaerobic Respiration processes but ATP is produced more in Aerobic than Anaerobic. In Aerobic respiration, water and carbon dioxide and the end products whereas in Anaerobic respiration, alcohol is the end product. Also, oxygen is present in Aerobic respiration which is the opposite in the case of Anaerobic respiration.
4. Are NCERTs the only books to be followed for respiration in Plants?
NCERT Biology has presented and explained the concepts and theories of different topics in a concise manner. Students can easily read and study the chapters due to the use of simple language as well as diagrams for understanding different processes. Also, there are several short, long answer type questions and Multiple Choice Questions (MCQs) which will help the students test themselves and evaluate their process of learning. This will also provide them with the ground to analyze and improve in their areas of weakness.
5. Where do students get extra notes on Respiration in Plants online?
Vedantu is an online educational platform that functions with the purpose of making online classes easier and self-studying a part of the learning process. Study materials by Vedantu are crisp, concise, and well-explained which will help students in understanding the chapters and also provide them with the scope of analysis during revision. All previous years’ question papers and sample papers are updated as per the latest syllabus so that students can have an idea of the pattern and weightage of questions and marks in the paper. All the notes are in downloadable PDF format for free.