The heart
Common errors:
- Left and right reversed: remember, in a labelled diagram, the left side of the heart is on the right side of the page (as if you are looking at someone facing you)
- Missing valves: the tricuspid and bicuspid valves are between atria and ventricles; semi-lunar valves are at the base of the aorta and pulmonary artery
- Wrong vessel connections: the aorta connects to the left ventricle, the pulmonary artery to the right ventricle
- Equal-thickness walls: the left ventricle wall must be drawn noticeably thicker than the right
The nephron
Common errors:
- Bowman's capsule not cupping the glomerulus: the capsule must surround the ball of capillaries
- Missing labels: loop of Henle, proximal convoluted tubule, distal convoluted tubule, collecting duct
- Arrows showing wrong direction of flow: filtrate flows from Bowman's capsule through the tubule to the collecting duct
Leaf cross-section
Common errors:
- Palisade and spongy mesophyll in wrong positions: palisade is on top (near upper epidermis), spongy is underneath
- Stomata on the upper surface: most stomata are on the lower epidermis
- Missing air spaces in spongy mesophyll: these are essential for gas exchange
General drawing rules
Single clear pencil lines. No shading. Proportions must be accurate. Label lines drawn with a ruler, horizontal, touching the structure. Title and magnification included.