How is Transpiration Related to Photosynthesis? A Guide for Plant Lovers

If you are a plant lover, you might have wondered how plants make their own food and use water. You might have heard of the terms transpiration and photosynthesis, but do you know what they mean and how they are related? In this article, we will explain the concepts of transpiration and photosynthesis, and how they are connected in the life cycle of plants.

What is Transpiration?

Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers Water is necessary for plants but only a small amount of water taken up by the roots is used for growth and metabolism. The remaining 97–99.5% is lost by transpiration and guttation

Transpiration occurs through the stomatal apertures, which are small pores on the surfaces of leaves. The stomata are bordered by guard cells that open and close the pore in response to various environmental stimuli and can regulate the rate of transpiration to reduce water loss

Transpiration has several purposes for plants, such as:

  • Providing the water for photosynthesis
  • Transporting mineral ions from the roots to the shoots
  • Cooling the plant as water evaporates
  • Creating a negative pressure that pulls water from the roots to the leaves

What is Photosynthesis?

Photosynthesis is how plants use sunlight to create their food from carbon dioxide and water Photosynthesis occurs in the chloroplasts, which are specialized organelles in plant cells that contain chlorophyll, a green pigment that absorbs light energy.

Photosynthesis can be divided into two stages: light reactions and dark reactions. In the light reactions, water is split into oxygen and hydrogen ions, and the light energy is converted into chemical energy in the form of ATP and NADPH. In the dark reactions, also known as the Calvin cycle, carbon dioxide is fixed into organic molecules using the ATP and NADPH produced in the light reactions

Photosynthesis is essential for plants because it:

  • Produces glucose, which is used as an energy source and a building block for other organic compounds
  • Releases oxygen, which is vital for aerobic respiration and life on Earth
  • Reduces carbon dioxide, which is a greenhouse gas that contributes to global warming

Transpiration and photosynthesis are closely related because both involve the exchange of gases between the plant and the atmosphere. Transpiration allows carbon dioxide to enter the leaf interior and oxygen to escape during photosynthesis. Hence, transpiration is generally considered to be merely an unavoidable phenomenon that accompanies the real functions of the stomata

However, transpiration also affects photosynthesis in several ways, such as:

  • Maintaining a high water potential in the leaf cells, which prevents wilting and plasmolysis
  • Delivering water to the chloroplasts, which is required for the light reactions of photosynthesis
  • Influencing the stomatal conductance, which determines how much carbon dioxide can enter the leaf
  • Modulating the leaf temperature, which affects the enzyme activity and reaction rates of photosynthesis

Therefore, transpiration and photosynthesis have a complex relationship that depends on various environmental factors, such as light intensity, humidity, temperature, wind speed, soil moisture, etc. Plants have to balance their water loss and carbon gain to optimize their growth and survival.


Transpiration and photosynthesis are two important processes that occur in plants. Transpiration is the loss of water from aerial parts of plants, while photosynthesis is the production of food from carbon dioxide and water using light energy. Transpiration and photosynthesis are related because both involve gas exchange between the plant and the atmosphere, and both affect each other in various ways. Understanding how transpiration and photosynthesis work can help us appreciate the amazing abilities of plants and their role in our environment.

Doms Desk

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