Why Do Plants Need Photosynthesis & Cellular Respiration?

During photosynthesis, plants produce the substance they require to survive and store it until they need it. During cellular respiration, plants carry out chemical reactions to derive energy from the products of photosynthesis.

Close up of Tree
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Plants conduct photosynthesis and cellular respiration to create, store and use energy.


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Plants transform light energy into chemical energy during photosynthesis.

During photosynthesis, plants transform light energy into chemical energy that living organisms can use. Plants absorb water from the soil and carbon dioxide from the air to produce sugars. Plants also release oxygen as a by-product during photosynthesis.


Green leafy indoor plant.
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Plants convert glucose into pyruvic acid during glycolisis.

During glycolysis, plants convert the simple sugar known as glucose into pyruvic acid and produce energy. This process occurs with or without oxygen in the cytoplasm of plant cells.

Cellular Respiration

Close up view of leaves
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During cellular respiration, plants use oxygen to further break down the products of glycolysis.

During cellular respiration, plants use oxygen to further break down the products of glycolysis in the mitochondria of plant cells. This process releases more energy, carbon dioxide and water.

Edriaan Koening

Edriaan Koening began writing professionally in 2005, while studying toward her Bachelor of Arts in media and communications at the University of Melbourne. She has since written for several magazines and websites. Koening also holds a Master of Commerce in funds management and accounting from the University of New South Wales.