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.
