BIOLOGICAL DRAWINGS FROM MICROSCOPE SLIDES A comparative analysis

ELODEA LEAVES showing one or more hook cells on the edge of a leaf

M

low A cell arrangement OK but: proportions are off; tip of hook cell inaccurate, chloroplasts too big for cell … overall, too stylised for a drawing

M

N proportions way off; hook cell curved on wrong side; inconsistent representation of the cell wall

low M angle between leaf and hook cell is a bit too wide

A tip of hook cell doesn’t show its main special feature i.e. thick cell wall

M

high A cells a bit wide and too rounded at ends

M

M

N cell shapes wrong cells don’t look like part of a leaf interlocking of cells doesn’t match slide hook tip has not been thickened! chloroplasts drawn too large

M

A cell outlines too wavy; tip of hook cell inaccurate; chloroplasts drawn carelessly (have hair!)

M

A cells too far apart; shapes don’t interlock well

M

M

M immediately obvious which cells have been drawn

A cell shapes don’t interlock enough chloroplasts too big for cells cell wall thickness too variable

LEAF TEARS showing a stoma and guard cells surrounded by epidermal cells

some shape mismatch sketchy lines chloroplasts open! A

M could have shown: membranes of plasmolysing cells, thick edges of guard cells around the stoma opening

M shapes, proportions and spacing excellent

A guard cells drawn far too large and cell shapes don’t match

N significant mismatch of shapes and sizes

M could have shown membranes of plasmolysing cells air bubble!

M obvious from shapes which cells have been drawn

A cell junctions misplaced shapes don’t match the specimen very well

specimen is clearly well understood by person drawing M

N epidermal cell shapes a poor match and way too small compared to guard cells; not enough cells drawn

M accurate, but ideally should show a couple more complete cells

A nuclei and shapes don’t match specimen very well

N mismatch of shapes and proportions; cells being “scalloped” off first cells; two cells drawn as one?

A guard cells way too small

M

A cells too angular guard cells too small

M clear match

A cell junctions don’t match and proportions are off

A cell proportions off: three need to be narrower for M

M clear match to specimen

M starts of walls of surrounding cells show that these cells are part of a larger piece of tissue

A guard cells drawn too elongated epidermal cell shapes do not match specimen well

SPIROGYRA a unicellular organism that lives in threads with other Spirogyra

…but why would you even try to draw something this hard? M