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Question Video: Understanding How the Intensity of Light Affects Photosynthesis Chemistry

How does the intensity of light affect photosynthesis?

03:02

Video Transcript

How does the intensity of light affect photosynthesis? (A) Light of greater intensity decomposes the oxygen produced during the reaction. (B) Light of lesser intensity uses a greater amount of carbon dioxide per minute. (C) Light of lesser intensity creates fewer free radicals and leads to less decomposition of chlorophyll. (D) Light of greater intensity creates surplus energy, which is stored in cellulose in the plant stem. Or (E) light of greater intensity increases the rate of reaction of photosynthesis.

In this question, we need to understand how the intensity of light affects photosynthesis. We can answer this question if we first explain the photosynthesis reaction and then explain its limiting factors.

The photosynthesis reaction is an essential chemical process because it generates sugars from carbon dioxide and water molecules. The sugars produced can later fuel metabolic activities that help plants thrive. The chemical reaction process also replenishes atmospheric oxygen because it generates one oxygen molecule per carbon dioxide or water molecule.

Photosynthesis reactions tend to happen in the chloroplasts of most plants. The reactions occur here because chloroplasts contain a photosensitive chemical called chlorophyll. The chlorophyll absorbs blue light and red light, reflecting green light, making the plant appear green. The energy from the absorbed light then drives photosynthesis reactions.

The equation describes how the photosynthesis reaction occurs in chloroplasts. We should notice that the term light is above the reaction arrow. The carbon dioxide and water usually only combine in the chloroplasts because the chloroplasts can provide the energy needed for turning carbon dioxide into glucose.

We can study the reaction equation to determine some of the limiting factors of the photosynthesis reaction process. The equation suggests that carbon dioxide concentration and light intensity are both limiting factors of the photosynthesis reaction. Plants can only readily synthesize product glucose molecules if they have enough carbon dioxide molecules and chemical energy derived from light.

Scientists find they can increase or decrease the rate of photosynthesis reactions by changing the light intensity. They can increase the photosynthesis reaction rate as they increase the intensity of light. They can similarly reduce light intensity to decrease the photosynthesis reaction rate.

So the answer to the question “How does the intensity of light affect photosynthesis?” is (E): light of greater intensity increases the rate of reaction of photosynthesis.

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