Final answer:
When fatty acids are released by lipase, the pH decreases due to the release of H+ ions. Organisms may adjust the ratio of saturated and unsaturated fatty acids in their cell membranes to maintain membrane fluidity across temperature fluctuations.
Step-by-step explanation:
When fatty acids are liberated by lipase, the pH of the solution decreases. This occurs because fatty acids are acidic in nature, releasing hydrogen ions (H+) into the solution upon liberation, increasing the acidity. As the concentration of H+ ions increases, the pH value falls because pH is a measure of the acidity of a solution, with lower pH values representing higher acidity.
Regarding organisms and membrane fluidity, to maintain fluidity at different temperatures, an organism might use different proportions of saturated and unsaturated fatty acid tails in their phospholipids to adapt their cell membranes. Unsaturated fatty acids, which have double bonds and kinks in their tails, prevent tight packing and thus maintain fluidity at low temperatures. Conversely, saturated fatty acids, without double bonds, allow for tighter packing and might be increased in response to high temperatures to maintain structure.