Drawing techniques P.1

BIOLOGY TAS guide (III)

DOs and DON'Ts in making Biological drawings:

A)Notes on biological drawings

The making of accurate drawings is an essential skill for Advanced level biology students. Students are required to make drawings of external features of whole specimens, parts of specimens, dissections and prepared slides.

Students should not the following points:

  1. A drawing should be genuine and accurate record of what has been seen.DO NOT copy diagrams from books with little resemblance to the specimen, dissection or prepared slideunder investigation.
  2. For low power drawings, only the outline of the structures or tissues needs to be drawn.DO NOT draw Individual cells, they are required only for high power drawings.
  3. Draw with bold, fark, smooth lines. Shading and the use of crayons are not encouraged.
  4. Avoid making drawings on both sides of a paper.
  5. In making a drawing, first decide what you want to show. Then plan your drawing to fit on the page. it is imporant that the various parts of the structures are drawn in proportion.
  6. Drawings should be large, neat and tidy.
  7. All relevant structures should be fully and clearly labelled using pencil. Each label should be connected to the appropriate part of the drawing by a clear labelling line. The labelling lines should run as horizontal as possible and should not intersect with one another. Do not label too close to the drawings, and do not writeon the drawing itself.Distribute the labels well around the drawing so that the labelling lines can be kept reasonably short.
  8. Every drawing should include a title, the magnification power, and the plan of view of the specimen (such as transverse section, longitudinal section).
  9. Make additional drawings if important details are too small to be shown in a low power drawing. this can be done by making a simple drawing of the main features, and other drawings on details of small parts only. for examples, the recording of a transverse section of a stem should include a low power plan of the section and high power drawings of different cells types as requried to show the detail of the cells.
  10. If suffices to show the internal structural details in a small representative sector of the specimen which shows repetitive features.
  11. It is sometimes appropriate to make short notes close to the labels. Such annotated drawings are particularly valuable as they combine a record of structures with related functions and/or biological interests.

Note : / High power magnification means the use of the 40X or 60X objective lens and the total magnification power up to 400X to 600X. The purpose of these drawings is to show the cell details.
. / Low power magnification means the use of the 10X or lower objective lens and the total magnification power not beyond 100X. The purpose of these drawings is to show the arrangement of tissues in the structure.
. / Whole mount specimen means to observe with the naked eyes only.

B)Dos and Don’ts

Dos / Don’ts
Always use a pencil, and a pencil only, for the drawing, the labels, the title – everything / Do not use ink, or colour, or ball-pen.
Use an HB pencil. It is neither too hard nor too soft.
Use a good quality eraser.
Your drawing should be a plain line drawing. / Do notshade or blacken structures, such as the nuclei. Do not use shading to create3-D effects. Biological drawings are generally 2-D drawings (flat).
Always draw boundary lines free-hand. / Do not draw a cell with ruler or compass even when the cells have very regular shape.
Lines should be single, thin, firm from the beginning to the end, evenly dark. / Do not draw lines of uneven thickness, lines that fade out, and Do not go over the same line two or more times.
Lines should be continuous and should join neatly. / Do not leave meaningless gaps or have lines crossing for no reason at all.
Lines should be reasonably steady, straight: / Do not draw shaky, wavy lines:
Centralize your drawing well and make the most of the available drawing space. / Do not cram too many drawings, often of unrelated things, on the same page. On the other hand, Do not push everything into one corner and leave most of the page unused. See how much you have to draw and label, and lay out your drawing accordingly.
Todraw straightguide-lines always use a transparent plastic ruler with undented edges. / Do not draw guide-lines free-hand, even when they are very short.
Guide-lines should be straight, plain, and whenever possible, horizontal. / Do not tip guide-lines with arrows:
Distribute your labels well around the drawing so that guide-lines can be kept reasonably short. / Do not make guide-lines exceedingly long and Do not have too many guide-lines crossing your drawing.
The gap between the end of the guide-line and the label should be short, say 2mm.
The other end of the guideline should touch the part you wish to label: / Do not leave a large gap; Do not stop short of the structure you label:
Use a simple kind of print when you label: / Do not use the cursory form and Do not use capital letters in labeling:
Labels should be concise (unless otherwise stated, e.g. for annotated diagrams) and should fit into one line: / Do notunderline labels or place the label above the guide-line:
Always give a title. Use the words of the question to phrase your title. / Do not give a name to a specimen, even if you know it. You could be wrong! If something is referred as specimen A and you conclude from your observation that it is, say a T.S. of a root, Do not call it " T.S. of a root ". The title should be " T.S. of specimen A ". Give a name only when you are asked to identify the specimen.
Write the title at about 2cm below the drawing. / Do not place the title at an ambiguous position, such as mid-way between two drawings.
By all means imitate the style of the drawings in your books. / DO NOT COPY THE DRAWINGS OR MEMORIZE THEM

C)TAS Sample drawings

  1. Making Low-power drawings:
Show the tissue layout / draw the whole or a representative part of the section to show the relative position of different types of tissues
When making 'Low Power' drawings, NO individual cells should be drawn.
  1. Making HP drawings:
The purpose is to show detailed cellular structures of a particular tissues or cell types, it is not necessary and time-consuming to draw a complete section through an organ in high power;
Don’t draw too many cells! Draw their representatives or certain typical cells are usually adequate

Sample marking

  1. Drawing of whole mount specimen(w.m.)
means to observe with the naked eyes only.


A3 : 1

Reason

  • Title is missing. This drawing shows poor resemblance to the specimen and is done rather casually. However most of the important biological features are shown. Segmentation in the abdomen, a feature which can be observed, is missing. Antennae, mouthparts and legs are poorly drawn.
  • Lines can be smoother.
  • Though labels are correct, marks given should not be based mechanically on the number of correct labels alone, but should rather base on an overall impression of the drawing as a whole.
ugh magnification is shown.
A3 : 3

Reason

  • This drawing shows a moderate degree of resemblance to the specimen.
  • Important biological features are shown. The proportion of the legs to the rest of the body is not accurate. The antennae, look broken, should be stated as such or indicated by broken line. Some details of the legs, e.g. segments, claws, pads, spurts, etc. are missing.
  • Lines are clear and mostly steady though slightly too thick.
  • Labels are appropriate except that the region for thorax should be extended to cover those thoracic segments where the legs arise.
  • The title should specify that the "lateral view" not the "lateral surface" of the grasshopper is being drawn.


A3 : 5

Reason

  • It shows a high degree of resemblance to the specimen.
  • Important biological features are shown. The shape and the proportions of various parts are good.
  • Most labels are correct.
  • Lines are clear and smooth.
  • Title and magnification are appropriate.

Low-power drawing of T.S. Ileum

First diagramA3 : 4

Reason

/ The drawing shows an acceptable degree of resemblance to the specimen. The four layers of the ileum wall are clearly shown. The proportion of the various layers are acceptable except that the muscularis mucosa is a bit thick.
/ Double lines should be used to show the thickness of the wall of the blood vessels.
/ Labels are neatly arranged but the mucosa is not labelled. They could have been grouped to show the four basic layers.
/ The title and magnification are appropriate.

Second diagram A3 : 3

Reason / This drawing shows good resemblance to the slide of the ileum with good proportion of the various layers.
/ The dots in the submucosa could have been drawn better. Circles should not be used in the longitudinal layer. Cell, e.g. goblet cell and its label should not be shown in L.P. drawings.
/ Label lines should not cross : line for villi and lacteal. Labels such as the "columnar epithelium mucus membrane" and "the smooth muscle layer" are intercepted by long bracket of the mucosa. In general, labels are a bit crowded on the right-hand side. There are a number of wrong labels : the circular muscle had been wrongly identified as the longitudinal muscle and the longitudinal muscle had been wrongly identified as the serosa. Certain features in the submucosa was wrongly labelled as the circular muscle layer.
/ The title can be bigger. Perhaps a smaller section of ileum wall should be drawn to avoid too much detail in the drawing.

Third diagram A3 : 1

Reason

/ This drawing is like a sketch and shows little resemblance to the specimen. The four layers : mucosa, submucosa, muscularis externa and serosa are not clearly shown by lines.
/ No biological details such as blood vessels and the two muscle layers have been included.
/ The labels are neatly arranged.
/ The title is spelled wrongly. It is not informative as to indicate how the ileum has been sectioned to give the view shown.

Marking and reasons:

First diagramA3 : 2

Reason / Some of the labels are missing.
/ Poor resemblance. Poor drawing on blood vessels.

Second diagramA3 : 4

Reason

/ Good resemblance. Spreaded lines.
/ Enough labels. No magnification.
/ Good scale. Hepatic portal vein is too thick. No anus.

Third diagramA3 : 3

Reason / Good resemblance,. Good scale, Good labels,
Labels are too close to the drawing,
The lines are not smooth enough.
/ The shape of liver is not true.
The stomach is too large

End