AQA A Level Biology复习笔记3.5.10 Required Practical: Dissecting Mass Transport Systems

• Dissections are a vital part of scientific research
• They allow for the internal structures of organs to be examined so that theories can be made about how they function
• There are ethical concerns surrounding dissections
  • People worry about how the animals for dissections are raised and killed
  • It goes against the religious beliefs of some individuals

   

• The biological specimen used for dissection should be from a reputable source and should be disposed of in the correct manner
• If multiple specimens are being dissected then they should be taken from individual organisms of the same species and roughly the same age

Image showing a heart dissection. The pencil passes through the right ventricle into the right atrium via the tricuspid valve. Remember that just like in diagrams the right ventricle appears on the left side of the heart. You can distinguish between the left and right ventricles also by looking at their size; the left ventricle is much larger than the right.

Apparatus

• Scissors
• Scalpel
• Tweezers / Forceps
• Dissection board
• Paper towels
• Biological specimen
• Pins

Method

• A lab coat, gloves and eye protection should be worn
  • To avoid contamination with biological material (which could cause an allergic reaction)

   

• Place the specimen on the dissecting board
• Use the tools to access the desired structure
  • When using the scalpel cut away from your body and keep your fingers far from the blade to reduce the chance of cutting yourself
  • Scissors can be used for cutting large sections of tissue (cuts do not need to be precise)
  • Scalpel enables finer, more precise cutting and needs to be sharpe to ensure this

   

• Use pins to move the other sections of the specimen aside to leave the desired structure exposed

Limitations

• It can be hard to see some of the smaller, finer structures within organs
• The specimens do not reflect how the tissue would look in a living organism
• If only a single specimen is dissected then anomalies found within that specimen may be ignored or glossed over