Understandings:
3.3.U1: One diploid nucleus divides by meiosis to produce four haploid nuclei.
3.3.U2 The halving of the chromosomes number allows a sexual life cycle with fusion of gametes.
3.3.U3: DNA is replicated before meiosis so that all chromosomes consist of two sister chromatids.
3.3.U4: The early stages of meiosis involve pairing of homologous chromosomes and crossing over followed by condensation.
3.3.U5: Orientation of pairs of homologous chromosomes prior to separation is random.
3.3.U6 Separation of pairs of homologous chromosomes in the first division of meiosis halves the chromosome number.
3.3.U7: Crossing over and random orientation promotes genetic variation.
3.3.U8: Fusion of gametes from different parents promotes genetic variation.
Applications:
3.3.A1 Non-disjunction can cause Down syndrome and other chromosome abnormalities. Studies showing age of parents influences chances of non-disjunction.
3.3.A2: Description of methods used to obtain cells for karyotype analysis – e.g. chorionic villus sampling and amniocentesis and the associated risks.
Skills:
3.3.S1: Drawing diagrams to show the stages of meiosis resulting in the formation of four haploid cells
3.3.U1: One diploid nucleus divides by meiosis to produce four haploid nuclei.
3.3.U2 The halving of the chromosomes number allows a sexual life cycle with fusion of gametes.
3.3.U3: DNA is replicated before meiosis so that all chromosomes consist of two sister chromatids.
3.3.U4: The early stages of meiosis involve pairing of homologous chromosomes and crossing over followed by condensation.
3.3.U5: Orientation of pairs of homologous chromosomes prior to separation is random.
3.3.U6 Separation of pairs of homologous chromosomes in the first division of meiosis halves the chromosome number.
3.3.U7: Crossing over and random orientation promotes genetic variation.
3.3.U8: Fusion of gametes from different parents promotes genetic variation.
Applications:
3.3.A1 Non-disjunction can cause Down syndrome and other chromosome abnormalities. Studies showing age of parents influences chances of non-disjunction.
3.3.A2: Description of methods used to obtain cells for karyotype analysis – e.g. chorionic villus sampling and amniocentesis and the associated risks.
Skills:
3.3.S1: Drawing diagrams to show the stages of meiosis resulting in the formation of four haploid cells