biology: working as a biologist

• mag= size of diagram
•           -------------------
•           real size

• mag= size of image
•           -----------------
•           size of object

mag= eye piece X objective

• - Scanning: 3D image
• - Transmisson: internail detail
• (SEM + TEM)

- When magnification increases the field of view goes down.

• - Compund: two seperate lens stystems, one for each eye. Shows small body in 3D (e.g. ant)
• - Compound: two or more seperate lenses. Shows interal structure of cells.

SA:V - number of units of surface area. E.g. as the organism gets bigger the ratio or surface area to volume gets smaller.

• Osmosis: movement of water across a semi permeable membrane from a high concentration to a low concentration.
• E.G. cell membrane will allow water but not salt.

Diffusion: molecules of solute spread from areas of low concentration in the solvent.

• Solvent: substance that dissolves the solute into it.
• Solute: substance that is dissolved into the solvent.
• E.G. water (solvent) will have salt dissolve into it (solute).

Hypotonic: less solute (salt) molecules outside the cell, which causes the water to be sucked in that direction. E.G. the cell will gain water and grow larger.

Hypertonic: more solute (salt) molecules outside the cell, which causes the water to be sucked in that direction. E.G. the cell will shrink and may die.