6.1 Reproduction

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Question 37
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Cell division by meiosis forms gametes. Three steps of this process involve DNA replication, a first cellular division, and a second cellular division. The graph below shows the mean mass of DNA per cell before, during, and after meiosis.

A line graph plotting the mean mass of DNA per cell on the y-axis against time in hours on the x-axis. The vertical axis is labeled 'Mean mass of DNA per cell (arbitrary units)' ranging from 0 to 14. The horizontal axis is labeled 'Time (hours)' ranging from 0 to 9. The plotted line starts at (0, 6) and remains horizontal at 6 until (2, 6). From (2, 6) it rises linearly to (4, 12). It stays horizontal at 12 from (4, 12) to (5.5, 12). At 5.5 hours, it drops vertically to (5.5, 6). It remains horizontal at 6 until (7, 6). At 7 hours, it drops vertically to (7, 3). From 7 to 9 hours, it remains horizontal at 3.

Use the graph to answer the following questions:

a.

During which time interval is the DNA in the chromosomes being copied?

[2]
b.

At which two times does a cell division event occur?

[2]
c.

What is the mean mass of DNA (in arbitrary units) in a completed gamete?

[1]
d.

What is the expected mean mass of DNA (in arbitrary units) in a zygote formed by the fusion of two of these gametes?

[1]

6.1 Reproduction Questions

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