Q49 - Lacandonia Flower ABC Model
Lacandonia schismatica is a rare Mexican plant with an unusual flower morphology. In most flowering plants, the ABC model of floral development predicts concentric whorls: sepals (A genes), petals (A+B genes), stamens (B+C genes), and carpels (C genes). In Lacandonia, the positions of stamens and carpels are reversed, with stamens in the center and carpels surrounding them.
The figures show three possible gene expression patterns (I, II, III) that could explain Lacandonia’s unusual floral morphology.
True or false?
Q49.1. Lacandonia schismatica flower morphology could be explained by gene expression pattern I.
Q49.2. Flowers of Lacandonia schismatica will lose both petals and carpels if flowers follow gene expression pattern II.
Q49.3. Flowers of Lacandonia schismatica will lose only petals if flowers follow gene expression pattern III.
Q49.4. Lacandonia flowers form typical berries after pollination and fruit ripening.
Q49.5. Tepals, like sepals, need only A gene expression.
Question reproduced from IBO 2023, Theoretical Paper 2, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF