Scientific diagrams

[sidzeman]

Our teacher has told us there will be guaranteed be a question on drawing a scientific diagram of xylem and phloem or blood cells in our trials
Unfortunately I've forgotten my year 7 basics and forgot the rules of drawing a diagram
Pls remind me and if you can provide examples of scientific diagrams that we need to know for the bio course thank!

[pikachu975]

Our teacher has told us there will be guaranteed be a question on drawing a scientific diagram of xylem and phloem or blood cells in our trials
Unfortunately I've forgotten my year 7 basics and forgot the rules of drawing a diagram
Pls remind me and if you can provide examples of scientific diagrams that we need to know for the bio course thank!

For xylem and phloem you need to be able to draw a transverse section:
https://image.slidesharecdn.com/1monocotdicot-101019024059-phpapp01/95/chapter-9-transport-in-plants-lesson-1-monocotyledons-and-dicot-23-728.jpg?cb=1287523931
Here's a good one (The diagram on the left)

And you need to know how to draw a longitudinal section:
http://www.bbc.co.uk/staticarchive/bd77a28b8e10ecd031c7db5199597705007e270f.jpg
Remember to label "perforations" for those circular stuff on the xylem (or you can draw them just as horizontal lines with a gap in the middle. For phloem label the "sieve plates" as those circular plates and label "companion cells" with the nuclei inside of them.

For blood cells, red blood cell is 6-8 um and white blood cell is 12-15 um. Make sure to include a scale in these e.g. 1 um = 1 cm. Red blood cells make sure you draw the two arc-shaped lines (like dimples) and label them as biconcave and make sure the shape of the RBC is circular. For WBC the shape is less circular and more elliptical and you must draw a nucleus and label that.

[Opengangs]

Hi, sidzeman!

For scientific diagrams, you should always draw what you see. For example, if you're drawing transverse and longitudinal cuts, you draw what you see, and not what you expect to see. Drawing what you expect to see defeats the purpose of a first-hand investigation. I know there were a few people who were marked down in our practical trial exam because they were drawing what is expected, and not their actual.

Furthermore, you should draw with pencil (2B, I think, was the recommended style) and label everything.
For a full checklist, feel free to see here.

[sidzeman]

Would these diagrams be appropriate?
Also: are the labelling lines not meant to have arrowheads?

[pikachu975]

Would these diagrams be appropriate?
Also: are the labelling lines not meant to have arrowheads?

The transverse section on the right are missing cambium (middle of xylem/phloem) and pith (the centre).

[sidzeman]

ahhhh I see thank you
Also, did you guys learn the functions of all these structures or just how to draw them - it doesn't really specify in the dotpoint

[pikachu975]

ahhhh I see thank you
Also, did you guys learn the functions of all these structures or just how to draw them - it doesn't really specify in the dotpoint

Yes. You know the function of xylem and phloem already from another dot point. Companion cells have a nucleus and I guess supply the energy for the phloem so that translocation can be carried out.

[sidzeman]

Sorry so what are the structures again?
Phloem is composed of living sieve cells which are joined end to end, with perforations to allow the movement of sap

What is xylem composed of and what is the purpose of sieve plates in phloem

[angelahchan]

Sorry so what are the structures again?
Phloem is composed of living sieve cells which are joined end to end, with perforations to allow the movement of sap

What is xylem composed of and what is the purpose of sieve plates in phloem

This is pretty late, but xylem is composed of two  tissues: xylem vessels (the wood of the stem) and tracheids. Xylem are dead, hollow tubes strengthened by lignin which provides support.
I'm not sure you need to know the function of sieve plates, since it wasn't in my notes, but I googled it anyway. Apparently the pores in the sieve plates can block phloem sap from flowing out when the phloem cell is damaged, protecting the phloem sap from intruding animals. (I'm assuming they close off but idk)