Essential Idea: The evolution of multicellular organisms allowed for cell specialization and cell replacement.
At SHS, Topic 1.1 is taught in the following class unit(s):
1.1.U1  ​According to the cell theory, living organisms are composed of cells.
  • State the three parts of the cell theory.
  • Outline evidence that supports the cell theory.
  • Compare the use of the word theory in daily language and scientific language.
1.1.U2  Unicellular organisms carry out all functions of life.
  • Outline the functional characteristics of life.
1.1.U3  ​Cell Surface to volume is an important limitation to cell size.
  • ​Outline the activities occurring in the volume and at the surface of the cell.
  • Calculate the surface area, volume and SA:V ratio of a cube.
  • Explain the benefits and limitations of using cubes to model the surface area and volume of a cell.
  • Describe the relationship between cell size and the SA:V ratio of the cell.
  • Explain why cells are often limited in size by the SA:V ratio.
  • List three adaptations of cells that  maximize the SA: volume ratio.
1.1.U4  ​Multicellular organisms have properties that emerge due to the interaction of their cellular components. 
  • Define and provide an example of a multicellular organism.
  • Define and provide an example of a unicellular organism.
  • Define “emergent property.”​
  • Provide an example of emergent properties at different hierarchical levels of life.
1.1.U5  ​Specialized tissues can develop by cell differentiation in multicellular organisms.
  • Define tissue.​
  • Outline the benefits of cell specialization in a multicellular organism.
  • Define differentiation.​
1.1.U6  ​Differentiation involves the expressions of some genes and not others in a cell’s genome.
  • Describe the relationship between cell differentiation and gene expression.
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.
  • Define zygote and embryo.
  • List 2 key properties of stem cells that have made them on the active areas of research in biology and medicine today.
  • Explain why stem cells are most prevalent in the early embryonic development of a multicellular organism.
  • Contrast the characteristics of embryonic, umbilical cord and adult somatic stem cells.
  • Define totipotent, multipotent and pluripotent.
​1.1.A1  ​Questioning the cell theory using atypical examples, including striated muscle, giant algae and aseptate fungal hyphae.
  • Describe features of striated muscle fibers that make them a discrepancy from a atypical cell.
  • Describe features of red blood cells that make them a discrepancy from a atypical cell.
  • Describe features of aseptate fungal hyphae that make them a discrepancy from a atypical cell.
  • Describe features of giant algae that make them a discrepancy from a atypical cell.​
​​1.1.A2  ​Investigation of functions of life in Paramecium and one named photosynthetic unicellular organism.
  • Describe characteristics of Paramecium that enable it to perform the functions of life.
  • Describe characteristics of Chlamydomonas that enable it to perform the functions of life.
1.1.A3  ​Use of stem cells to treat Stargardt’s disease and one other named condition.
  • Outline why stem cells are used in medical research and treatment.
  • Outline the cause and symptoms of Stargardt’s disease.
  • Explain how stem cells are used in the treatment of Stargardt’s disease.
  • Outline the cause of leukemia.
  • Explain how stem cells are used in the treatment of leukemia.​
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.
  • Discuss the benefits and drawbacks in using adult stem cells.
  • Discuss the benefits and drawbacks in using embryonic stem cells.
  • Discuss the benefits and drawbacks in using cord blood stem cells.
1.1.S1  ​Use of a light microscope to investigate the structure of cells and tissues.  Practical 1
  • Label the names of parts of the microscope.
  • Define magnification.
  • Given the magnification of the ocular and objective lenses, calculate the total microscope magnification.
  • Define "field of view."
  • Outline how to determine the diameter of a field of view using low power magnification.
  • Calculate the field of view diameter of a microscope under medium or high power.
  • Outline how to estimate the size of a sample in the microscope field of view.
  • Demonstrate how to focus the microscope on  a sample.​
1.1.S2  ​Drawing of cell structures as seen with the light microscope.
  • Demonstrate how to draw cell structures seen with a microscope using sharp, carefully joined lines and straight edge lines for labels.​
1.1.S3  ​Calculation of the magnification of drawings and the actual size of structures and ultrastructures shown in drawings or micrographs. 
  • Define micrograph.
  • State why the magnification of a drawing or micrograph is not the same as the magnification of the microscope.
  • Use a formula to calculate the magnification of a micrograph or drawing.
  • If given the magnification of a micrograph or drawing, use a formula to calculate the actual size of a specimen.​
1.1.NOS1  ​Looking for trends and discrepancies- although most organisms conform to cell theory, there are exceptions.
  • Define "trend" and explain why trends are useful in scientific study.
  • Define "discrepancy" and explain why discrepancies are useful in scientific study.
  • List features that would be considered a “trend” related to the cell theory.​
1.1.NOS2  ​Ethical implications of research- research involving stem cells is growing in importance and raises ethical issues.
  • Explain why biological research must take ethical issues into consideration.

In the News
I give many of my IB Biology resources away, for the benefit of students and teachers around the world. 
If you've found the materials helpful, please consider making a contribution of any amount to this Earthwatch Expedition Fund. 

​Did I forget something?  Know of a mistake? Have a suggestion?  Let me know by emailing me here. Cheers!

Before using any of the files available on this site, please familiarize yourself with the Creative Commons Attribution License. 
​​​It prohibits the use of any material on this site for commercial  purposes of any kind.  ​

"When we try to pick out anything by itself, we find it hitched to everything else in the Universe." 
 John Muir,   1911