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Do Plants Need Light?

Author(s): Nancy Moreno, PhD, and Barbara Tharp, MS.

The Science of Plant Growth

Students observed the following properties of plant growth and development in this activity.

Plants require light, water, air and soil to grow. Only producers, such as green plants, are able to make the molecules needed for life from simple compounds in the air, soil and water. Almost all producers use energy from the sun to make food through the process of photosynthesis. During photosynthesis, light energy is trapped and transformed into chemical energy that can be used by cells. Green plants need only water (H2O) and carbon dioxide (CO2) in the presence of light to manufacture sugar molecules and other carbohydrates, such as starch. Plants use the energy held in carbohydrates to fuel chemical reactions and to make other molecules that are necessary for life.

Light is necessary for the production of new plant material. During photosynthesis, producers absorb energy from the sun and use it to combine carbon from carbon dioxide with water to make sugars and other carbohydrates. Through this amazing process, light energy from the sun is converted into chemical energy stored in the bonds between atoms that hold molecules together. Plants use energy stored in these molecules to build other compounds necessary for life. 

Note: Plants growing in dark conditions sometimes develop tall spindly stems. This process, called etiolation, occurs when plants use their energy to grow upward in search of light. 

Funded by the following grant(s)

National Institute of Environmental Health Sciences, NIH

National Institute of Environmental Health Sciences, NIH

My Health My World: National Dissemination
Grant Number: 5R25ES009259
The Environment as a Context for Opportunities in Schools
Grant Number: 5R25ES010698, R25ES06932