Video Transcript
Complete the statement. If light intensity is low and less
chlorophyll is synthesized by the plant, the rate of photosynthesis blank. (A) Increases, (B) decreases, or
(C) remains constant.
This question asks about the
relationship between light intensity and the plant’s gene expression. To answer it, we need to address
the relationship between light intensity, chlorophyll synthesis, and the rate of
photosynthesis.
Chlorophyll is the green pigment
found in the chloroplasts of many plants. It absorbs the light energy that is
required for photosynthesis, which allows plants to produce their own source of
sugars. The amount of chlorophyll that is
synthesized depends upon light intensity. Typically, the lower the light
intensity, the less chlorophyll is synthesized. This usually results in a lower
rate of photosynthesis, as less light energy can be absorbed by these photosynthetic
pigments.
Various experiments have shown that
the rate of photosynthesis has a positive correlation with the amount of chlorophyll
present. In other words, the more
chlorophyll present, the higher the rate of photosynthesis.
We know that when light intensity
is low, the synthesis of chlorophyll decreases. We also know that when the amount
of chlorophyll decreases, the rate of photosynthesis decreases as well. Therefore, the rate of
photosynthesis decreases when light intensity is low. So the word that should fill in the
blank in the statement, and the correct answer to this question, must be (B),
decreases.
