Respiration In Plants (Do Plants Respire Experiment)

Do Plants Respire

All living things use a process called respiration to obtain energy from food to stay alive. Plants do respire, like all other living things.

Diagram showing respiration definition Plants, photosynthesis and stomata

What Is Respiration In Plants

Respiration in plants is the process used by plants to convert the glucose made during photosynthesis into energy which fuels the plants’ cellular activities​1​. During the process of respiration, plants consume food, and the products of respiration become the energy source.

What Is Photosynthesis In Plants

Photosynthesis is the process where light energy from sunlight is converted into chemical energy stored in glucose that can later be used in respiration. The photosynthesis process occurs in green plants that contain chlorophyll. Plants essentially create their own food through photosynthesis.

When Do Plants Respire

Respiration is a continuous process. Plants respire both during the day and at night when there is an absence of sunlight. There are two types of respiration: dark respiration and photo respiration. These are two separate kinds of respiration that occur within the green tissues in plants​2​. Dark respiration occurs both in the dark and in the light, while photo respiration only occurs in the presence of sunlight​2​.

When Does Photosynthesis Occur

While plants respire all the time, day and night, photosynthesis only occurs during the day in the presence of sunlight. The process of photosynthesis does not take place at night due to the absence of sunlight​3​.

Respiration and Photosynthesis in Plants

There is a close relationship between respiration and photosynthesis. They are the opposite of each other in many ways​4​.

In plant respiration, food and oxygen (H2O) are converted into energy and carbon dioxide (CO2). Food is the product of photosynthesis, while oxygen can be from the atmosphere or photosynthesis.

In photosynthesis, sunlight energy and carbon dioxide are converted into food and oxygen for respiration.

Do Plants Need Oxygen

Plants can respire in the presence or absence of oxygen using anaerobic and aerobic respiration.

Anaerobic respiration processes take place when there is a lack of oxygen.

Depending on the amount of sunlight, plants can give out or take in oxygen and carbon dioxide​5​.

Dark – Only dark respiration takes place in the presence of oxygen. Oxygen for respiration is consumed to break down glucose into carbon dioxide to release energy for plant growth.

Dim sunlight – The photosynthesis rate roughly equals the rate of respiration. Respiration consumes all the oxygen photosynthesis generates. Photosynthesis also uses all the carbon dioxide gas released as a product of respiration. As a result, no gaseous exchange takes place with the environment.

Bright sunlight – The conversion of carbon dioxide and water into oxygen and glucose in photosynthesis is faster than respiration produces carbon dioxide. Atmospheric gas exchange takes place.

During day time, processes of photosynthesis produce oxygen and glucose faster than respiration consumes it. Photosynthesis also uses carbon dioxide faster than respiration produces it. Oxygen surplus is released into the air, and unused glucose is stored in the plant for later use.

This is why plants are crucial to human and animal survival. Plants are the source of energy for everything. Without photosynthesis, we wouldn’t have oxygen or food to stay alive.

Do Plants Breath?

Diagram of human lungs. What is the difference between cellular respiration and breathing?

People breathe. Animals breathe.

Do plants breathe?

Breathing refers to the act of inhaling air and then expelling it—the reactions through gas exchange fuel living objects and the environment.

The exchange of gases takes place in the lung. The act of breathing involves the physical inhalation of oxygen and the pushing out of carbon dioxide.

Plants do not breathe in the strictest sense of the word​6​. The structures for exchange are also different.

Rather than lungs, plants exchange gases through pores called stomata.

During respiration and photosynthesis, the exchange in plants is done through stomata using diffusion, not breathing.

Because of these parallel processes, people sometimes imprecisely call respiration in plants “breathing.” But strictly speaking, breathing and respiring in plants are not the same.

But respiration in plants is strikingly similar to why living objects breathe.

This is why it is not entirely incorrect if you’re not using this as an answer in exams but rather use it as an analogy

Plants don’t breathe in and out using their lungs. The air exchange involves different specialized structures and mechanisms. But it is a good analogy for the concept of respiration nonetheless.

Respiration in Plants and Animals

Plants are not the only ones that can respire. Animals also respire.

Respiration in animals is similar to respiration in plants in terms of its role in gas exchange.

In animals, the exchange of gasses occurs in the lung through diffusion​7​.

Cellular respiration then takes place by converting glucose into energy and oxygen into carbon dioxide.

The products are then released and removed from the living objects through breathing.

Plant Respiration Experiment

pink flower and green leaves in bowls of water

How Do Plants Breathe Experiment

Prep Time: 5 minutes
Active Time: 10 minutes
Additional Time: 1 hour
Total Time: 1 hour 15 minutes

Here is a popular science experiment to visually see how plants “breathe”.

In this experiment, we can see how gases produced during photosynthesis and respiration are released into the environment.

Materials

  • water
  • plant (e.g. a flower or a leaf. Pick it from a living plant, not one that has fallen onto the ground)
  • sunlight (optional)

Tools

  • shallow bowl

Instructions

Steps

  1. Submerge the plant into a bowl of water. The flower or leaf may float to the top, but try to make at least part of the plant stay underwater. Leave in water, air bubbles on stem
  2. Put the bowl under the sunlight and wait. (You can also leave it in the dark but it may take longer to see results.) Leaf in water, air bubbles on leaf
  3. After an hour, observe the plant’s surface. There should be some air bubbles formed on the pedals or the leaf.

Explore

  1. Observe different parts of the plant. Do air bubbles form everywhere?
  2. Do air bubbles form if you leave the plant in the dark?

Did you try this project?

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Oxygen and carbon dioxide pass in and out of the stomata in the plants through diffusion.

When the plant is submerged in the water, bubbles of oxygen or carbon dioxide released are trapped, and they stick to the leaves or petals temporarily.

Since these gases are lighter than water, if you shake the plant, the bubbles will quickly rise to the surface and burst. It is similar to you releasing a breath underwater.

Books On Plants, Photosynthesis, And Respiration in Trees

This is Book 8 in the Super Smart Science book series.

This colorful picture book is a great introduction to botany. It teaches key vocabulary such as the leaf, stem, root, xylem, cellulose, chloroplast, photosynthesis and respiration, and pronunciation. It is thorough and easy to understand.

Other topics covered in the series, including biology, chemistry, astronomy, anatomy, and physiology, are also great additions to the kids’ library.

This book presents a lot of fun facts about plants. For example, did you know that planting one tree produces enough oxygen to support four people for one year?

Scientific concepts such as photosynthesis are well explained by excellent graphics and interesting stories about Max Axiom. Max is a superhero and a super scientist. He really helps make science learning fun.


References

  1. 1.
    Brown MH, Schwartz RS. Connecting photosynthesis and cellular respiration: Preservice teachers’ conceptions. J Res Sci Teach. Published online September 2009:791-812. doi:10.1002/tea.20287
  2. 2.
    GRAHAM D. Effects of Light on “Dark” Respiration**Abbreviations are as follows: AMP, adenosine monophosphate; ADP, adenosine diphosphate; ATP, adenosine triphosphate; CoA, coenzyme A; DCMU, dichlorophenyl dimethyl urea; DHAP, dihydroxyacetone phosphate; Fructose-1,6-P2, fructose-1,6-bisphosphate; glucose-6-P, glucose-6-phosphate; GOGAT, glutamate synthase, E.C. 1.4.1.13 (l-glutamate: NADP-oxidoreductase (transaminating); OAA, oxaloacetate; OPPP, oxidative pentose phosphate pathway; Pi, inorganic phosphate; PEP, phosphoenolpyruvate; PGA, 3-phosphoglycerate; PYR, pyruvate; RPPP, reductive pentose phosphate pathway (Calvin cycle); RuBP, ribulose bisphosphate; TCA, tricarboxylic acid. Metabolism and Respiration. Published online 1980:525-579. doi:10.1016/b978-0-12-675402-5.50019-2
  3. 3.
    Atkin OK, Scheurwater I, Pons TL. Respiration as a percentage of daily photosynthesis in whole plants is homeostatic at moderate, but not high, growth temperatures. New Phytologist. Published online February 22, 2007:367-380. doi:10.1111/j.1469-8137.2007.02011.x
  4. 4.
    Hunt S. Measurements of photosynthesis and respiration in plants. Physiologia Plantarum. Published online February 28, 2003:314-325. doi:10.1034/j.1399-3054.2003.00055.x
  5. 5.
    Makino A, Mae T. Photosynthesis and Plant Growth at Elevated Levels of CO2. Plant and Cell Physiology. Published online January 1, 1999:999-1006. doi:10.1093/oxfordjournals.pcp.a029493
  6. 6.
    Seymour J, Longden B. Respiration—that’s breathing isn’t it? Journal of Biological Education. Published online September 1991:177-183. doi:10.1080/00219266.1991.9655203
  7. 7.
    Fitting JW. From Breathing to Respiration. Respiration. Published online December 12, 2014:82-87. doi:10.1159/000369474

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