Essential Idea: The evolution of multicellular organisms allowed for cell specialization and cell replacement.
1.1.U1 According to the cell theory, living organisms are composed of cells.
1.1.U2 Unicellular organisms carry out all functions of life.
1.1.U3 Cell Surface to volume is an important limitation to cell size.
1.1.U4 Multicellular organisms have properties that emerge due to the interaction of their cellular components.
1.1.U5 Specialized tissues can develop by cell differentiation in multicellular organisms.
1.1.U6 Differentiation involves the expressions of some genes and not others in a cell’s genome.
1.1.U7 The capacity of stem cells to divide and differentiate along different pathways is necessary in embryonic development and also makes stem cells suitable for therapeutic uses.
1.1.A1 Questioning the cell theory using atypical examples, including striated muscle, giant algae and aseptate fungal hyphae.
1.1.A2 Investigation of functions of life in Paramecium and one named photosynthetic unicellular organism.
1.1.A3 Use of stem cells to treat Stargardt’s disease and one other named condition.
1.1.A4 Ethics of the therapeutic use of stem cells from specially created embryos, from the umbilical cord blood of a newborn baby and from an adult’s own tissues.
1.1.S1 Use of a light microscope to investigate the structure of cells and tissues. Practical 1
1.1.S2 Drawing of cell structures as seen with the light microscope.
1.1.S3 Calculation of the magnification of drawings and the actual size of structures and ultrastructures shown in drawings or micrographs.
1.1.NOS1 Looking for trends and discrepancies- although most organisms conform to cell theory, there are exceptions.
1.1.NOS2 Ethical implications of research- research involving stem cells is growing in importance and raises ethical issues.
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