Paper 2 style question on topic 1.1 Intro to cells

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Summary list for 1.1 Introduction to cells

Cell theory

  • According to cell theory, living organisms are composed of cells.
  • Organisms consisting of only one cell carry out all functions of life in that cell, e.g. Paramecium, Chlorella.
  • Identifying the characteristics of living things (Mr H. Gren - metabolism, response, homeostasis, growth, reproduction, excretion & nutrition).
  • Surface area to volume ratio is important in the limitation of cell size.
  • Multicellular organisms have properties that emerge from the interaction of their cellular components, (Emergent properties).
  • Specialised tissues can develop by cell differentiation in multicellular organisms.
  • Differentiation involves the expression of some genes and not others in a cell.
  • Stem cells can divide and differentiate along different pathways in embryonic development which makes stem cells useful for therapeutic uses (e.g. Stargardt's disease).
  • There are ethical concerns about the use of embryo stem cells.

Calculating magnification and size

  • Calculate the magnification of an electron microscope image from a scale bar.
  • Calculate specimen size using a scale bar.
  • Calculate specimen size using magnification.