Question

Briefly describe O2 transfer from the atmosphere into the mitochondria of an insect cell. Name four variables that if altered would result in a decrease in rate of O2 uptake by the cell. Include the direction of change for the variable (increase or decrease) along with a brief explanation that references Fick’s Law of Diffusion where appropriate.

Answer 1

-Air enters the insect’s body through valve-like openings in the exoskeleton. These openings called spiracles . Air flow is regulated by small muscles that operate one or two flap-like valves within each spiracle contracting to close the spiracle, or relaxing to open it.
-Aftet passing through a spiracle, air enters a longitudinal trachel trunk, eventually diffusing throughout a complex, branching network of trachral tubes that subdivides into smaller diameters and reaches every part of the body. At the end of each tracheal branch, a special cell provides a thin, moist interface for the exchange of gasses between atmospheric air and a living cell. Oxygen in the tracheal tube first dissolves in the liquid of the tracheole and then diffuses into the cytoplasm of an adjacent cell. At the same time, carbon dioxide, produced as a waste product of cellular respiration, diffuses out of the cell and, eventually, out of the body through the tracheal system.

*high air flow rates can cause cell damage due to shear forces
*Increasing temperatures inversely affects both the volumetric mass transfer coefficient and oxygen solubility in culture medium. Oxygen solubility in pure water falls with increasing temperature
*climate conditions also responsible .