Gibberellin is a plant growth regulator that plays a role in the germination of barley seed. Gibberellin production is triggered by water uptake. State the site of gibberellin synthesis in a barley seed during germination.
Using Fig. 5.1, describe how barley seed germination index is related to water potential.
Suggest reasons for the relationship shown in Fig. 5.1.
During barley seed germination, gibberellin triggers the synthesis of enzymes. State the name of one of these enzymes and the exact site where it is synthesized.
Some plants are grown commercially for their flowers. Many of these are short-stemmed varieties. Two factors that influence stem height are: • gibberellin • the $Le/le$ gene. The $Le/le$ gene has two alleles, $Le$ and $le$. Suggest one benefit of growing a flowering-plant variety with short stems.
Explain how the $Le/le$ gene and gibberellin work together to affect stem height in plants.