Chromosome behaviour in mitosis and meiosis
Cambridge A-Level Biology (9700) · Unit 5: The mitotic cell cycle · 8 flashcards
Chromosome behaviour in mitosis and meiosis is topic 5.2 in the Cambridge A-Level Biology (9700) syllabus , positioned in Unit 5 — The mitotic cell cycle , alongside Replication and division of nuclei. In one line: The spindle, composed of microtubules, is responsible for accurately segregating the sister chromatids to opposite poles of the cell during anaphase. This ensures each daughter cell receives a complete set of chromosomes.
Marked as AS Level: examined at AS Level in Paper 1 (Multiple Choice), Paper 2 (AS Structured Questions) and Paper 3 (Advanced Practical Skills). The same content may also be assumed in Paper 4 (A Level Structured Questions).
The deck below contains 8 flashcards — 1 definition and 7 key concepts — covering the precise wording mark schemes reward. Use the definition card to lock down command-word answers (define, state), then move on to the concept and calculation cards to handle explain, describe, calculate and compare questions.
The role of the spindle during mitosis
The spindle, composed of microtubules, is responsible for accurately segregating the sister chromatids to opposite poles of the cell during anaphase. This ensures each daughter cell receives a complete set of chromosomes.
What the Cambridge 9700 syllabus says
Official 2025-2027 spec · AS LevelThese are the exact learning outcomes Cambridge sets for this topic. The candidate is expected to be able to do each of these on the relevant paper.
- describe the behaviour of chromosomes in plant and animal cells during the mitotic cell cycle and the associated behaviour of the nuclear envelope, the cell surface membrane and the spindle (names of the main stages of mitosis are expected: prophase, metaphase, anaphase and telophase)
- interpret photomicrographs, diagrams and microscope slides of cells in different stages of the mitotic cell cycle and identify the main stages of mitosis
Cambridge syllabus keywords to use in your answers
These are the official Cambridge 9700 terms tagged to this section. Mark schemes credit responses that use the exact term — weave them into your answers verbatim rather than paraphrasing.
Tips to avoid common mistakes in Chromosome behaviour in mitosis and meiosis
- › Distinguish between repairing a single cell and tissue repair; mitosis produces genetically identical cells to replace those that are lost.
- › Distinguish between nuclear division (mitosis) and the broader cell cycle; remember that DNA replication occurs in S phase, which is part of interphase.
- › Remember that all nucleated body cells retain a full set of genetic information, and telomeres shorten but do not change in number.
- › Ensure you draw daughter chromosomes as single chromatids once they have separated and are moving toward the poles in anaphase.
- › Focus on centrioles as the Microtubule Organising Centre (MTOC) that assembles and disassembles spindle fibres to move chromosomes.
Describe the key events occurring during prophase of mitosis.
Chromatin condenses into visible chromosomes (each with two sister chromatids), the nuclear envelope breaks down, and the spindle apparatus begins to form from the centrosomes. Microtubules attach to the kinetochores of the sister chromatids.
What is the role of the spindle during mitosis?
The spindle, composed of microtubules, is responsible for accurately segregating the sister chromatids to opposite poles of the cell during anaphase. This ensures each daughter cell receives a complete set of chromosomes.
Outline the events that occur during metaphase.
The chromosomes line up along the metaphase plate (equator) of the cell, with each sister chromatid attached to a spindle fiber originating from opposite poles. This ensures equal distribution of genetic material.
Describe the main events during anaphase.
Sister chromatids are separated and pulled to opposite poles of the cell by the shortening of spindle fibers. Each chromatid is now considered an individual chromosome.
What occurs during telophase of mitosis?
The chromosomes arrive at the poles and begin to decondense. The nuclear envelope reforms around each set of chromosomes, and the spindle apparatus disappears. Cytokinesis usually occurs concurrently.
What happens to the nuclear envelope during mitosis?
The nuclear envelope breaks down during prophase, allowing the spindle fibers to access the chromosomes. It reforms during telophase around the separated chromosomes, creating two distinct nuclei.
Explain the process of cytokinesis in animal cells.
In animal cells, cytokinesis involves the formation of a cleavage furrow, a contractile ring of actin and myosin filaments that pinches the cell membrane inward, eventually dividing the cytoplasm into two daughter cells.
How does cytokinesis differ in plant cells compared to animal cells?
Plant cells form a cell plate, a new cell wall, between the two daughter nuclei. Vesicles containing cell wall material fuse at the midline, expanding outward until the new cell wall completely separates the two cells.
More topics in Unit 5 — The mitotic cell cycle
Chromosome behaviour in mitosis and meiosis sits alongside these A-Level Biology decks in the same syllabus unit. Each uses the same spaced-repetition system, so progress in one informs the next.
Key terms covered in this Chromosome behaviour in mitosis and meiosis deck
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