Cell DivisionAQA GCSE Biology: Flashcards

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What is the role of the nucleus in cell division?

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What is the role of the nucleus in cell division?: The nucleus stores genetic information in the form of chromosomes, which are made of DNA. During cell division, these chromosomes are distributed to daughter cells to ensure genetic information is passed on.
Name the three main stages of the cell cycle.: Interphase (including growth and DNA replication) Mitosis (nuclear division) Cytokinesis (cytoplasm division)
What happens during interphase of the cell cycle?: The cell grows and increases in size. DNA is replicated so that each chromosome consists of two identical sister chromatids. Organelles are also replicated to provide enough for both daughter cells.
Define mitosis.: Mitosis is the process of nuclear division that produces two genetically identical daughter cells, each with the same number of chromosomes as the parent cell.
What are the three main purposes of mitosis in organisms?: Growth - increasing the number of cells in an organism Repair - replacing damaged or dead cells Asexual reproduction - producing genetically identical offspring in some organisms
Explain the importance of cell division in the growth and development of organisms.: Cell division increases the number of cells in an organism, allowing it to grow larger. This is essential for development from a single fertilised egg into a multicellular organism with specialised tissues and organs.
What is cancer and how does it relate to cell division?: Cancer is a disease caused by uncontrolled cell division. Cancer cells divide repeatedly without the normal control mechanisms that limit cell division, forming tumours that can spread to other parts of the body.
Define meiosis.: Meiosis is a type of cell division that produces four genetically different haploid cells (each with half the number of chromosomes) from one diploid cell. It occurs during the production of gametes (sex cells).
What is the difference between the chromosome numbers in cells produced by mitosis and meiosis?: Mitosis produces two diploid cells with the same number of chromosomes as the parent cell. Meiosis produces four haploid cells with half the number of chromosomes as the parent cell.
Explain what independent assortment is during meiosis.: Independent assortment is the random distribution of homologous chromosome pairs to daughter cells during meiosis I. Each gamete receives a random mix of maternal and paternal chromosomes, creating genetic variation.
Define crossing over in meiosis.: Crossing over is the exchange of genetic material between homologous chromosomes during meiosis I. Non-sister chromatids swap sections of DNA, creating new combinations of alleles on the same chromosome and increasing genetic variation.
How do independent assortment and crossing over contribute to genetic variation?: Independent assortment randomly distributes different combinations of chromosomes to gametes. Crossing over shuffles alleles between homologous chromosomes. Together, these processes ensure that gametes are genetically unique and offspring show variation.
Why is meiosis important for sexual reproduction?: Meiosis produces haploid gametes with half the chromosome number. When two gametes fuse during fertilisation, the diploid chromosome number is restored in the offspring. Meiosis also generates genetic variation through crossing over and independent assortment.
What is a chromosome?: A chromosome is a structure made of DNA and protein found in the nucleus. It contains genetic information in the form of genes arranged in a linear sequence.
Explain the difference between haploid and diploid cells.: Diploid cells contain two sets of chromosomes (one from each parent) and are represented as 2n. Haploid cells contain one set of chromosomes and are represented as n. Gametes are haploid; most other body cells are diploid.