3. Exchange - Practicals

Question 1

aim of required practical 5

Answer 1

-dissection of animal or plant gas exchange system or mass transport system or of organ within such a system

Question 2

describe precautions that should be followed when performing a dissection

Answer 2

● cover any cuts with a waterproof dressing
● when using a scalpel, cut away from body onto a hard surface
● when using a scalpel, use a sharp blade
● when using a scalpel, carry with blade protected / pointing down
● wear disposable gloves and disinfect hands / wash with soap
●disinfect surfaces/equipment
● safe disposal - put gloves / paper towels / organ in a separate bag / bin to dispose
● if poisonous chemicals / toxins involved, work in a well ventilated environment

Question 3

suggest an ethical consideration when dissecting animals

Answer 3

-morally wrong to kill animals just for dissection
-so use animals for dissection that have already been killed (humanely) for meat

Question 4

describe how you could prepare a temporary mount of a piece of plant
tissue for observation with an optical microscope

Answer 4

1. add a drop of water to glass slide
2. obtain a thin section of specimen and place on slide
3. stain (eg. with iodine / potassium iodide to view starch)
4. lower coverslip at angle using mounted needle without trapping air bubbles

Question 5

what are the rules of scientific drawing?

Answer 5

✓ look similar to specimen / image - draw parts to the same scale / relative size
✓ no sketching - only clear, continuous lines
✓ no shading / hatching
✓ include a magnification scale (eg. x 400)
✓ label with straight, uncrossed lines