Video Transcript
The graph provided shows the
results of incubating seeds in different concentrations of gibberellin, GA. Which of the following best
describes the trend shown? (A) As the concentration of GA
increases, the percentage of seeds that germinate decreases. (B) As the concentration of GA
increases, the percentage of seeds that germinate increases. Or (C) as the concentration of GA
increases, there is no significant effect on the percentage of seeds
germinating.
Most plant seeds are designed to
withstand harsh environmental conditions, such as cold winters and periods without
water. Seed dormancy is maintained by high
concentrations of a hormone called abscisic acid, or ABA, which controls water
uptake by the seed’s embryo tissues, allowing it to survive desiccation.
When the harsh environmental
conditions have passed, ABA concentration in the seed decreases. This allows water to enter the
seed’s embryo tissues. And at the same time, a hormone
called gibberellin, sometimes known as gibberellic acid or GA, is secreted. GA breaks down the starchy food
stores in the seed, allowing the embryonic plant to perform cellular respiration and
synthesize proteins, stimulating germination and the plant’s first growth.
This is reflected in the graph
provided by the question. As the concentration of GA
increases, the percentage of seeds germinating also increases. This means that we have found the
correct answer to this question. The answer choice that best
describes the trend shown in the graph is (B). As the concentration of GA
increases, the percentage of seeds that germinate increases.
