[Campbell Biology P.906] Based on the experiment described in Figure 39.16, what is the most... | Practice Question

Based on the experiment described in Figure 39.16, what is the most critical factor determining lettuce seed germination when exposed to sequences of red and far-red light?

  • A: The initial light exposure.
  • B: The duration of the dark period after light exposure.
  • C: The total amount of red light received.
  • D: The final light exposure before darkness.

Explanation

The "Conclusion" section of Figure 39.16 explicitly states: "The final light exposure is the determining factor." The experiment's results clearly show that even if seeds were exposed to red light earlier, a final exposure to far-red light inhibited germination, and vice versa.