[Campbell Biology P.299] Which statement correctly describes the information presented by th... | Practice Question

Which statement correctly describes the information presented by the x-axis in the provided histograms and its relation to the cell cycle?

  • A: The x-axis directly measures cell size, indicating that larger cells have more DNA.
  • B: The x-axis represents the relative amount of DNA per cell, with cells in G1 phase having approximately half the DNA content of cells in G2/M phase.
  • C: The x-axis shows the rate of cell division, with higher fluorescence indicating faster division.
  • D: The x-axis measures the number of chromosomes, and cells in S phase have twice the number of chromosomes as G1 cells.

Explanation

The passage states that the fluorescent chemical binds to DNA, and the flow cytometer records fluorescence level per cell, which in turn indicates the relative amount of DNA. Cells in G1 phase have a base amount of DNA 2C , while cells in G2/M phase have duplicated their DNA 4C , so G1 cells have half the DNA of G2/M cells.