Mitosis and the cell cycle: Students need to understand the three overall stages of the cell cycle but do not need to know the different phases of the mitosis stage.

The idea

This statement sets the depth of knowledge required for the cell cycle. You must understand its three overall stages: first, the cell grows and replicates its DNA so each chromosome is copied; second, the nucleus divides, distributing one complete set of chromosomes to each end of the cell; third, the cytoplasm and cell membranes divide to produce two genetically identical daughter cells. You do not need to name or describe the individual phases of mitosis, such as prophase, metaphase, anaphase and telophase. Assessment focuses on ordering the three stages, explaining the purpose of DNA replication and stating the outcome of the cycle, for example in a human cell with 46 chromosomes.

What earns the marks

• The first overall stage involves cell growth and replication of DNA, producing two copies of each chromosome.
• The second overall stage is nuclear division, in which one set of chromosomes moves to each end of the cell.
• The third overall stage is division of the cytoplasm and cell membranes, forming two daughter cells.
• The outcome is two genetically identical cells, each with the same chromosome number as the parent cell.
• Naming or describing individual phases of mitosis is not required for this specification.
• The three stages can be applied to growth, repair and asexual reproduction.

Common mistakes and how to put them right

• Listing prophase, metaphase, anaphase and telophase as required knowledge.

  Put it right by learning only the three overall stages.

• Treating DNA replication as part of nuclear division.

  Put it right by placing replication in the first growth stage, before the nucleus divides.

• Describing the cell cycle as producing four cells.

  Put it right by stating that it produces two genetically identical daughter cells.

Exam tips

• Learn a three-step sequence and use it to answer ordering or description questions.
• State the purpose of DNA replication, namely that each daughter cell receives a complete copy of the genetic material.
• If a question asks for detail beyond the three stages, keep your answer to the overall stages rather than inventing phase names.