Scheme of Work Cambridge International as & a level

Extension activity: Learners explain a number of ‘real-world’ applications of the importance of osmosis, including the basis of isotonic energy drinks and bathing solutions used during transport of organs for transplant.

Past and specimen papers

Past/specimen papers and mark schemes are available to download at www.cambridgeinternational.org/support (F)

5: The mitotic cell cycle

Syllabus ref. and Key Concepts (KC)	Learning outcomes	Suggested teaching activities
5.1 Replication and division of nuclei and cells KC1 KC3	5.1.1 Describe the structure of a chromosome. 5.1.2 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. 5.1.3 Outline the mitotic cell cycle. 5.1.4 Outline the role of telomeres in preventing the loss of genes from the ends of chromosomes during DNA replication. 5.1.5 Outline the role of stem cells in cell replacement and tissue repair by mitosis. 5.1.6 Explain how uncontrolled cell division can result in the formation of a tumour.	Learners work in groups of three or four to decide on three ideas they know about cell division. Then ask them to share their facts in groups and to compile a master list, with the most important at the top. Ask for ideas as a class, and find out which other groups agreed. To make this activity more effective and inclusive, do not choose learners on the basis of ‘hands up.’ Instead, choose learners at random. Use this opportunity to explain to learners the importance of mitosis in the production of genetically identical daughter cells during growth, replacement and repair (including the role of stem cells) and asexual reproduction (F) Learners explore the structure of chromosomes using a karyotype. Learners work together to group the chromosomes in pairs, and then identify the structures called sister chromatids, centromeres and telomeres. Learners could fix the karyograms that they produce into their study notes, to provide a useful reference point during subsequent lessons. Show a range of simplified and actual electron micrographs of chromosomes and their ultrastructure. Recommended animations which are good for consolidating learners’ understanding of packaging DNA include: www.hhmi.org/biointeractive/dna-packaging www.dnalc.org/resources/3d/07-how-dna-is-packaged-basic.html Learners sequence a set of diagrams into a flow chart showing changes that occur to result in a tumour (must include an abnormal mass from which two arrows emerge to a benign growth and a cancerous (malignant) growth. (I) Tell learners that they must work in pairs or groups of three to identify the ‘odd one out’ in a series of three key words. Display a series of key words in triplets on the board or provide on paper, and ask learners to discuss which one is less related to the other two terms. They must justify their decisions. Examples include: ‘chromatid, chromosome, centromere?’ (here, centromere would be the odd one out as it does not consist of a strand of DNA identical to the others). (F)