Researchers grew seedlings of corn, Zea mays, in loose and compact sand. The researchers measured the amount of time required for the cells in the growing root tips of the seedlings to double in number. The mean cell doubling times for the two groups of seedlings are shown in Figure 1.
Figure 1. Mean cell doubling times for the growing root tips of Zea mays seedlings planted in loose or compact sand
Based on the sample means, which of the following conclusions about the cells in the growing root tips of Zea mays seedlings is best supported by the results of the experiment?
answer choices
The cells of the root tips grow to larger sizes when the seedlings are planted in compact sand than when the seedlings are planted in loose sand.
The average rate of mitotic cell division is greater for the root tips growing in loose sand than for the root tips growing in compact sand.
The average cell cycle time is greater for the root tips growing in compact sand than for the root tips growing in loose sand.
More cells are produced per unit of time in the root tips growing in compact sand than in the root tips growing in loose sand.
