TAS Requirements for Biological drawings According to TAS

TAS Requirements for Biological drawings

• According to TAS, we can identify the following criteria for assessing biological drawings of students: 1. Accuracy : resemblance to the specimen correct shape and proportion 2. Smooth and clear lines 3. Correct labels or annotations 4. Title, plan of view and magnification 5. Large, overall neatness including the arrangement of labels and label lines

TAS AREA A 2 : This assesses the quality of biological drawings. The criteria is as follow. (1) (2) The biological drawing technique (A) Draw with sharp, clear and closed lines (B) Shaped with dots (C) Congruence with the specimen (D) index lines without crossing Annotations Students are required to give notes on two structures. Each structure is provided with 1 mark.

The following drawings High power magnification drawings Low power magnification drawings Whole mount specimen drawings

Orientation • Apart from naming the structures of your drawing correctly, you should describe how the section of the specimen is cut: • The followings are some common terms used to describe sections:

• 1. Transverse section (T. S. ) : at right angles to the long axis of a structure such as a stem; also known as cross section (X. S. ) • 2. Longitudinal section (L. S. ): along the long axis of a structure such as a stem • 3. Vertical section (V. S. ): at right angles to the surface of a structure such as the skin

• 4. Whole mount (w. m. ): e. g. onion epidermis • 5. Teased, macerated, smear, etc.

Orientation of sections

Title • Always give a title; • You can use the words of the question to phrase your title; NOT like this : T. S. of a root Like this : T. S. of specimen A • Include plan of view and magnification

• Write the title below the drawing and rather close to it; • Don’t place the title at too great a distance from the drawing or in an ambiguous position such as mid-way between 2 drawings; O. K. ? Structures of two guard cell

Low power and high power drawings

Low power drawing: • Low power magnification means the use of the 10 X or lower objective lens and the total magnification power not beyond 100 X. • Show the tissue layout / draw the whole or a representative part of the section to show the relative position of different types of tissues;

• Do not attempt to draw individual cells in a low power drawing; • Low power drawing does not mean a drawing showing the features as seen under a low power magnification of the microscope, eg. 5 x 10 !

High power drawing: • High power magnification means the use of the 40 X or 60 X objective lens and the total magnification power up to 400 X to 600 X. The purpose of these drawings is to show the cell details • Adjacent cells should be drawn in their proper positional relationships and proportionate size to one another;

• For plant cell, the cell wall is usually comparatively thick, a double line should be used to represent the thickness; • If the wall is thin, single line can be used; • If cellular structures such as cytoplasm, nuclei, vacuoles and starch grains are visible under high power, they should also be drawn and labeled

• The purpose is to show detailed cellular structures of a particular tissues or cell types, it is not necessary and timeconsuming 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!

Whole specimen means to observe with the naked eyes only.

Whole specimen drawing

• By all means imitate the style of the drawings in certain reference books, if that helps; BUT DO NOT COPY THE DRAWINGS OR MEMORIZE THEM !