Q18 - The ABC Gene Model of Monocot Flower Development

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

Flower Anatomy & Reproductive Structures

Botanists may identify plants to family using diagrams, showing the different floral parts (Fig. A). According to the ABC gene model, development of a flower is based on expression of the A-, class-B- and C-genes. In dicots, sepals develop if gene-A is expressed alone, petals develop if both gene-A and gene-class-B are expressed, stamens develop if both gene-class-B and gene-C are expressed, and an ovary develops if only gene-C is expressed. A, diagram of a monocot flower; B, tulip flower (a monocot), parts of the flower are removed in photo to the right; C, the ABC gene model of monocot flower development (I, ovary; II, stamens; III, petals; IV, sepals; the latter two are similar in most monocots). Gene-class-B consists of 3 genes B1–B3.

Figure 1. Figure 1.

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

A. Tulips do not have any sepals

B. Gene-C has different expression in monocots and dicots

C. Selective supression of gene C-expression in region II leads to development of unisexual flower

D. Complete development of stamens in the tulip requires the expression of gene-B1+gene-B3+gene-C

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Question reproduced from IBO 2015, Theoretical Exam A, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)