Q23 - Temperature-Dependent Sex Determination in Two Turtle Populations

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

British Territories in the Atlantic, Indian, Mediterranean and Pacific Oceans are vast new marine reserves which Green turtles (Chelonia mydas) and Hawksbill turtles (Eretmochelys imbricata) inhabit (1). Sex determination in turtles depends on the temperature of the nest, as shown for Chagos Archipelago hatchlings (2). Sand temperature in turn depends on the nest site (3). The majority of breeding occurs in peak breeding season, but a scarcity of males reduces breeding rates.

Figure 1 for Q23: Temperature-Dependent Sex Determination in Two Turtle Populations

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

A. Ascension produces an excess of female turtles.

B. The Chagos Archipelago produces a roughly balanced sex ratio of Hawksbill hatchlings.

C. Chagos island turtle breeding will be less disrupted by global warming, than Ascension island turtle breeding.

D. Conservationists should protect heavily shaded nest beaches as a priority.

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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