Prokaryotic cells
Bacteria cells (small and simple)
Eukaryotic cells
Plant and animal cells (large and complex)
Light microscope PURM
P: cheap
U: alive or dead
R(esolution): low
M(agnification): high
Electron microscope PURM
P: expensive
U: dead
R: high
M: high
Overall magnification =
Eye piece lens x Objective lens
Magnification =
Image size / object size
Mitosis
Cell division, growth and repair
Order of mitosis (6)
- Cell grows and number of sub cellular organelles increase
- Chromosomes double
- Chromosomes line up in centre
- Chromosomes are pulled apart
- Cell membrane begins to split
- Nucleus reforms forming 2 identical daughter cells
Diffusion
Particles move from high to low concentration
Liquid and gas only
Eg. Alveoli in lungs
Osmosis
Water moves from high to low concentration across a partially permeable membrane
Active transport
Particles move from low to high concentration requiring energy from respiration
Eg. Small intestine, roots
Osmosis required practical
Cylinders of potato, ends cut off
Weigh
Place in solution for 24 hrs
Dry to remove excess water
Weigh potato again
Calculate % change in mass (due to different starting masses)
Osmosis practical variables
Independent - conc of sugar solution
Dependant - mass of potato
Controlled - same potato
- length of potato
- diameter of potato
- same volume of solution
How is indirect contact spread eg.
Surfaces
How is direct contact spread eg.
Sexual contact
What are pathogens
Microorganisms that cause disease
HIV? Spread?
Virus
Sexual contact / sharing bodily fluids
HIV causes? Treatment?
Damages immune system
Antiretroviral drugs treatment
Salmonella? Spread?
Bacteria
Unhygienic food prep
Salmonella symptoms
Fever, diarrhoea
HIV symptoms
Fever, rash, muscle ache, fatigue
Measles? Spread?
Virus
Cough + sneeze
Measles symptoms
Fever, rash
