Final answer:
A #40 blade is commonly used in biology labs for dissection, and the length of the coat it leaves depends on the thickness of the tissue being cut.
Step-by-step explanation:
A #40 blade is commonly used in biology laboratories for dissection. The length of the coat left by a #40 blade depends on the thickness of the tissue being cut. Thicker tissues, such as muscle tissue, may leave a longer coat compared to thinner tissues, like skin or blood vessels.
For example, if you are dissecting a rat's muscle tissue with a #40 blade, it may leave a coat of approximately 1-2 millimeters. However, if you are dissecting thin skin tissue, the coat left may be minimal, around 0.5 millimeters or less.
It is important to handle the #40 blade with care and follow proper laboratory safety protocols to avoid injuries.