The cell cycle and why cells divide

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

2. 1.

   Ari reads the cell cycle wheel. In which segment is the cell's DNA copied?

   • The G1 segment
   • The mitosis segment
   • The S segment
   • The cytokinesis segment
3. 2.

   Bo watches a new cell form. It is growing and gathering building blocks, and its DNA is not copied yet. Which part of the wheel is it in?

   Use the picture in question 1.

   • G2, the second gap
   • No segment: a new cell rests before the cycle starts
   • M, the mitotic phase
   • G1, the first gap
4. 3.

   Esme reads the wheel. Which job happens in the mitotic phase?

   Use the picture in question 1.

   • The copied chromosomes are pulled apart and the cell splits
   • The cell grows and gathers energy before copying its DNA
   • The cell copies its DNA so each chromosome has two chromatids
   • The cell grows, copies its DNA and divides, from start to finish

5. Read this first

   Cycle wheel (model, not to scale), clockwise from the top

   G1, S, G2, mitosis (M), cytokinesis.

6. 4.

   Jun walks clockwise around the wheel, starting at G1. Which list shows the segments in order?

   • G1, G2, S, mitosis, cytokinesis
   • G1, S, G2, cytokinesis, mitosis
   • Cytokinesis, mitosis, G2, S, G1
   • G1, S, G2, mitosis, cytokinesis
7. 5.

   Kira looks at the wheel. Which segment comes straight after S?

   • G2, the second gap
   • Cytokinesis, the cell splitting
   • Mitosis, skipping the second gap
   • G1, the first gap
8. 6.

   Luz brackets part of the wheel as interphase. Which segments belong in the bracket?

   • No segment: interphase is a rest between cycles
   • G1, S and G2
   • Mitosis alone, since mitosis is the whole cycle
   • Mitosis and cytokinesis
9. 7.

   Noah compares two cube cells. Which cell has more surface area for each unit of its volume?

   • The 1 µm cell, with a ratio of 6
   • The 3 µm cell, because bigger cells exchange materials better
   • The 3 µm cell, since 54 is more surface area than 6
   • Neither: both cubes share the same ratio
11. 8.

    At the G1 gate, Ren learns that a cell has damaged DNA. What happens next?

    • The cell is held at the gate while the damage is repaired
    • The cell skips ahead to mitosis
    • The cell goes on into S, since a gate cannot stop a cell
    • The cell goes straight to cytokinesis and splits
12. 9.

    Tala reads about the gate in mitosis. What must be true before the sister chromatids are pulled apart?

    Use the picture in question 8.

    • Each pair of sister chromatids is attached to the spindle
    • The DNA has been copied for the first time
    • The cell has already divided its cytoplasm
    • The cell has doubled in size
13. 10.

    “model, not to scale” Zee reads about a mature nerve cell that does not divide. Where is it in the cell cycle?

    • In G0, outside the active cycle
    • In interphase, resting before its next division
    • In G1, getting ready to divide again soon
    • In mitosis, stuck partway through dividing