Replication and division of nuclei
Cambridge A-Level Biology (9700) · Unit 5: The mitotic cell cycle · 7 flashcards
Replication and division of nuclei is topic 5.1 in the Cambridge A-Level Biology (9700) syllabus , positioned in Unit 5 — The mitotic cell cycle , alongside Chromosome behaviour in mitosis and meiosis. In one line: A chromosome consists of DNA tightly wound around histone proteins. It's composed of two sister chromatids joined at the centromere. Telomeres are located at the ends.
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 7 flashcards — 2 definitions and 5 key concepts — covering the precise wording mark schemes reward. Use the 2 definition cards 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.
Describe the structure of a chromosome, including its key components
A chromosome consists of DNA tightly wound around histone proteins. It's composed of two sister chromatids joined at the centromere. Telomeres are located at the ends.
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 structure of a chromosome, limited to: • DNA • histone proteins • sister chromatids • centromere • telomeres
- explain the importance of mitosis in the production of genetically identical daughter cells during: • growth of multicellular organisms • replacement of damaged or dead cells • repair of tissues by cell replacement • asexual reproduction
- outline the mitotic cell cycle, including: • interphase (growth in G1 and G2 phases and DNA replication in S phase) • mitosis • cytokinesis
- outline the role of telomeres in preventing the loss of genes from the ends of chromosomes during DNA replication
- outline the role of stem cells in cell replacement and tissue repair by mitosis
- explain how uncontrolled cell division can result in the formation of a tumour
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 Replication and division of nuclei
- › 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.
Describe the structure of a chromosome, including its key components.
A chromosome consists of DNA tightly wound around histone proteins. It's composed of two sister chromatids joined at the centromere. Telomeres are located at the ends.
Explain the significance of mitosis in multicellular organisms regarding growth and repair.
Mitosis produces genetically identical cells, crucial for growth by increasing cell number. It also enables repair of damaged tissues by replacing dead or injured cells, ensuring functional restoration.
Outline the key events of interphase in the mitotic cell cycle.
Interphase involves cell growth in G1 and G2 phases, and DNA replication during the S phase. This ensures the cell has sufficient resources and genetic material before entering mitosis.
What is the role of telomeres and why is their function important?
Telomeres are protective caps at the ends of chromosomes. They prevent the loss of genes during DNA replication, maintaining the integrity of genetic information with each cell division.
Describe the role of stem cells in tissue repair.
Stem cells are undifferentiated cells that can divide by mitosis and differentiate into specialized cells. They replace damaged cells in tissues, facilitating repair and maintaining tissue function.
Explain how uncontrolled cell division can lead to tumor formation.
Uncontrolled cell division, often due to mutations, results in excessive cell proliferation. This forms a mass of cells called a tumor, which can be benign or malignant (cancerous).
Outline the main stages of the mitotic cell cycle.
The mitotic cell cycle consists of interphase (G1, S, G2), mitosis (prophase, metaphase, anaphase, telophase), and cytokinesis (cell division). These stages ensure accurate DNA replication and cell division.
More topics in Unit 5 — The mitotic cell cycle
Replication and division of nuclei 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 Replication and division of nuclei deck
Every term below is defined in the flashcards above. Use the list as a quick recall test before your exam — if you can't define one of these in your own words, flip back to that card.
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