BIO NOTES
28/1/21
Variables
Independent – changed.
Dependent – measured.
Controlled – all the same.
Extraneous – can’t be controlled but may affect results.
Accuracy and Position
Accuracy – a measure of how close a measurement comes to the actual or true
value of whatever is measured.
Precision – a measure of how close a series of measurements are to one another,
irrespective of the actual value.
Errors
Random – human error (doing more trials reduces the impact of random errors)
Systematic – equipment (to test for systematic errors, repeat experiment with
different equipment)
29/1/21
Definitions
Cell – basic structural and functional units of life. They are the smallest units.
Life processes
Mrs Gren - movement, respiration, sensitivity, growth, reproduction, excretion,
nutrition
The cell theory
- All organisms are composed of one or more cells.
- All cells arise from pre-existing cells.
- The cell is the smallest living organisation unit.
- Chemical reactions occur in cells.
Characteristic Light Microscope Electron Microscope
Energy Source light electrons
View live specimens? yes no
View colours? yes no
Magnification 400x 300,000x
Resolution low high
Measuring the size of cells
- Cells are usually measured in micrometres (μm)
- 1 μm = 0.001 mm (10-3 mm)
- 1 nm = 0.000001 mm (10-6 mm)
3/2/21
Types of Cells
, BIO NOTES
Prokaryotic Cells
- Do not contain membrane bound organelles.
- Do not have a nucleus.
- Very small (~1 μm, therefore have a good SA: V, ensures good supply of
nutrients by diffusion
Eukaryotic Cells
- Well organised, specialised cells
- Very large (10-100 μm)
- Contain membrane bound organelles (‘compartmentalised’)
Characteristic Prokaryotes - bacteria Eukaryotes – plants,
animals, fungi,
protists
Size Smaller (1-10 μm) Larger (10-100 μm)
DNA Circular (plasmid) Linear
Nucleus Absent Present
Level of Organisation Little (low) High
Organelles No membrane bound Contain membrane
organelles bound organelles
Chromosome Single and free 2 or more in nucleus
Cell Wall Most have a cell wall Cell wall (plants) made
made of peptidoglycan of cellulose
Ribosomes Present Present but different size
to prokaryotic
10/2/21
Nucleus
Structure – contains chromosomes which consist of DNA and protein.
Function – store and transmit genetic information.
Mitochondrion
Structure – two outer membranes with an infolded inner membrane to which
enzymes are attached.
28/1/21
Variables
Independent – changed.
Dependent – measured.
Controlled – all the same.
Extraneous – can’t be controlled but may affect results.
Accuracy and Position
Accuracy – a measure of how close a measurement comes to the actual or true
value of whatever is measured.
Precision – a measure of how close a series of measurements are to one another,
irrespective of the actual value.
Errors
Random – human error (doing more trials reduces the impact of random errors)
Systematic – equipment (to test for systematic errors, repeat experiment with
different equipment)
29/1/21
Definitions
Cell – basic structural and functional units of life. They are the smallest units.
Life processes
Mrs Gren - movement, respiration, sensitivity, growth, reproduction, excretion,
nutrition
The cell theory
- All organisms are composed of one or more cells.
- All cells arise from pre-existing cells.
- The cell is the smallest living organisation unit.
- Chemical reactions occur in cells.
Characteristic Light Microscope Electron Microscope
Energy Source light electrons
View live specimens? yes no
View colours? yes no
Magnification 400x 300,000x
Resolution low high
Measuring the size of cells
- Cells are usually measured in micrometres (μm)
- 1 μm = 0.001 mm (10-3 mm)
- 1 nm = 0.000001 mm (10-6 mm)
3/2/21
Types of Cells
, BIO NOTES
Prokaryotic Cells
- Do not contain membrane bound organelles.
- Do not have a nucleus.
- Very small (~1 μm, therefore have a good SA: V, ensures good supply of
nutrients by diffusion
Eukaryotic Cells
- Well organised, specialised cells
- Very large (10-100 μm)
- Contain membrane bound organelles (‘compartmentalised’)
Characteristic Prokaryotes - bacteria Eukaryotes – plants,
animals, fungi,
protists
Size Smaller (1-10 μm) Larger (10-100 μm)
DNA Circular (plasmid) Linear
Nucleus Absent Present
Level of Organisation Little (low) High
Organelles No membrane bound Contain membrane
organelles bound organelles
Chromosome Single and free 2 or more in nucleus
Cell Wall Most have a cell wall Cell wall (plants) made
made of peptidoglycan of cellulose
Ribosomes Present Present but different size
to prokaryotic
10/2/21
Nucleus
Structure – contains chromosomes which consist of DNA and protein.
Function – store and transmit genetic information.
Mitochondrion
Structure – two outer membranes with an infolded inner membrane to which
enzymes are attached.
