Physics for Life Sciences

(left) Experimental Subjects Musca Metallica awaiting immersion in a hot spa bath and (right) demonstrating ways to survive a rapid drop in temperature.

A new course, PHYS1201 - Life Science Physics, was introduced in 2000. This course examines selected topics in Physics that have been chosen to present material with direct relevance to various areas of Life Science. One challenge was to develop a new set of laboratory experiments that would not only continue to illustrate the basic physical principles, but also show students how they might be applied to various areas in Life Sciences. The experiments include:

• Specific heat. Students measure the specific heat of some biological materials. To minimise problems with the RSPCA and various ethics committees, some experimental animals are specimens of the domestic frankfurter (Canis thermophilis vulgaris). Students heat the specimens in hot water; any that remain uneaten are dropped into cold water and their specific heat calculated from the temperature rise of the water.
• Thermal Conductivity. Students heat one end of a frankfurter and estimate its thermal conductivity by measuring the rise in temperature at a distant point. Thermal insulation from the environment is achieved by cunningly placing the frankfurter between two halves of a suitable bread roll.
• Poikilotherms and heat loss. Students examine how different external coverings affect the heat loss when an animal is exposed to a rapid drop in temperature. The School of Physics has evolved a set of experimental animals (Musca metallica ) that enjoy a wide range of temperatures and don't object to having their internal temperature measured.
• Refractive index. Students invesitigate the problems caused by light passing through the air/water interface.They use the light emitted by specimens of the lesser cubefish, Blockus brassii , a type of shiny stonefish. This creature has an unusual hunting strategy that involves turning on a red light whenever a school of suitable fish pass nearby. Usually some of the fish will stop, only to be devoured immediately.

Students also conduct experiments on colour vision and mixing, variation of optical resolution with contrast, nuclear magnetic resonance, X-ray diffraction and ionising radiation.

John Smith