Topic 2 study guide
Topic 2: Cells
2.1 Cell Theory
2.1.1: Outline cell theory
Living organisms are composed of cells
Cells are the smallest unit of life
Cells come from pre-existing cells
2.1.2: Discuss the evidence for cell theory
Humans have not been able to find any living thing that is not made up of at least one cell
Robert Hooke first described cells when looking at cork through a microscope
Louis Pasteur´s experiments: he discovered that all cells must come fom pre-existing cells
2.1.3: State that unicellular organisms carry out all the functions of life
Unicellar organisms carry out all the functions of life. This includes metabolism, response, homeostatis, growth, reproduction and nutrition.
2.1.4: Compare the relative sizes of molecules, cell membrane thickness, viruses, bacteria, organelles and cells, using the appropriate SI unit.
Molecules (1 nm)
Thickness of membranes (10 nm)
Viruses (100 nm)
Bacteria (1 μm)
Organelles (up to 10 μm)
Cells (up to 100 μm)
2.1.5: Calculate the linear magnification of drawings and the actual size of specimens in images of known magnification
1. Measure the drawing with a ruler (either the length or width)
2. Measure the actual specimen (or use value given)
3. Convert units if necessary
4. Place the values into the equation: Magnification = length or width of drawing / length or width of actual specimen
5. If length of specimen is unknown but magnification is given: length or width of drawing / magnification
2.1.6: Explain the importance of surface area to volume ratio as a factor limiting cell size.
Rate of heat production, waste production and resource consumption of a cell is a function of its volume, whereas the rate of exchange of materials and energy is a function of its surface area. It the surface area to volume ratio gets too small then the substances will not be able to enter the cell fast enough to give energy to the reactions and waste products will build up within the cell. Additionally, the
2.1 Cell Theory
2.1.1: Outline cell theory
Living organisms are composed of cells
Cells are the smallest unit of life
Cells come from pre-existing cells
2.1.2: Discuss the evidence for cell theory
Humans have not been able to find any living thing that is not made up of at least one cell
Robert Hooke first described cells when looking at cork through a microscope
Louis Pasteur´s experiments: he discovered that all cells must come fom pre-existing cells
2.1.3: State that unicellular organisms carry out all the functions of life
Unicellar organisms carry out all the functions of life. This includes metabolism, response, homeostatis, growth, reproduction and nutrition.
2.1.4: Compare the relative sizes of molecules, cell membrane thickness, viruses, bacteria, organelles and cells, using the appropriate SI unit.
Molecules (1 nm)
Thickness of membranes (10 nm)
Viruses (100 nm)
Bacteria (1 μm)
Organelles (up to 10 μm)
Cells (up to 100 μm)
2.1.5: Calculate the linear magnification of drawings and the actual size of specimens in images of known magnification
1. Measure the drawing with a ruler (either the length or width)
2. Measure the actual specimen (or use value given)
3. Convert units if necessary
4. Place the values into the equation: Magnification = length or width of drawing / length or width of actual specimen
5. If length of specimen is unknown but magnification is given: length or width of drawing / magnification
2.1.6: Explain the importance of surface area to volume ratio as a factor limiting cell size.
Rate of heat production, waste production and resource consumption of a cell is a function of its volume, whereas the rate of exchange of materials and energy is a function of its surface area. It the surface area to volume ratio gets too small then the substances will not be able to enter the cell fast enough to give energy to the reactions and waste products will build up within the cell. Additionally, the