Q68 - Hormonal Correlates of the Cucumber Super-Ovary Phenotype

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

Scientists grew cucumber plants in different nutrient conditions to obtain either super ovary or normal ovary types. They labelled flowers when they emerged and observed the development of flowers. Based on the color and shape, corolla development was divided into four consecutive stages: green bud (G), green-yellow bud (GY), yellow bud (Y), and flowering (F). They also measured plant growth regulator concentrations in different flower developmental stages.

Fig.Q.68 A-D: Morphological characterization of the normal ovary and super ovary types, including corolla-stage progression over time, ovary length at anthesis, and fruit length at matched days after labeling. E-J: Concentration of cytokinins (iPA, ZR, DHZR), gibberellins (GA3, GA4) and auxin (IAA) in different flower developmental stages. In the super ovary type, two sub-stages were included. Double asterisks indicate statistically significant differences within one developmental stage.

Figure 1. Figure 1.

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

A. The corolla progression between stages was much delayed in the super ovary

B. The ovary at anthesis was on average much longer in the super ovary than the normal ovary, while at the same time courses after labelling, fruit length was not different between two types.

C. Gibberellins were increased in the super ovary during the early stages of corolla development, which corresponds to the enlarged corolla size.

D. Cytokinins appear to be the primary regulator for the time of flower opening in cucumber, whereas auxin is probably involved in the size control of corolla and fruit.

← Previous: Q67 Next: Q69 →

Question reproduced from IBO 2016, Theoretical Paper B, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)