Q16 - Antifreeze Proteins and Membrane Chemistry in Polar Fish

Theoretical B Real exam question - full text reproduced under IBO's CC BY-NC-SA 4.0 license

Comparative Thermoregulation Lipids & Membrane Biochemistry

The Royal Research Ship Sir David Attenborough and submarine Boaty McBoatface will explore British Antarctica. Life here exists below the freezing temperature of usual fish, which is determined by their osmolarity (1). Salt accounts for the majority of blood’s osmolarity. Antarctic fish are therefore prone to freezing, which usually occurs by the expansion of pre-existing ice crystals in the water. Some Antarctic fish o reduce their freezing point by > 2 C by secreting antifreeze proteins into the blood (2). Additionally, Antarctic fish must have an appropriate cell membrane chemistry, to prevent their membranes from becoming too rigid at low temperatures (3).

Figure 1 for Q16: Antifreeze Proteins and Membrane Chemistry in Polar Fish

Using the information and data, determine which of the statements are true or which are false.

A. Fish staying at great depth under floating ice shelves need to produce antifreeze proteins.

B. The anti-freeze proteins function mainly by increasing the osmolarity of the fish.

C. Antarctic fish have increased expression of phospholipid desaturases.

D. Antarctic fish have better temperature sensors and dynamic responses to temperature than temperate fish.

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Question reproduced from IBO 2017, Theoretical Exam B, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Official answer key & worked solutions