Outline how selective breeding was used to produce vigorous, uniform varieties of maize.
IR8 is a rice variety that was developed in the 1960s. It was produced by breeding together two different rice varieties: PETA, which gives a high yield, and DGWG, which is a dwarf variety. Fig. 6.1 is a diagram showing the three rice varieties. Suggest why IR8 is an improvement on the PETA variety of rice.
In 2009, scientists produced a new rice variety, IR64-Sub1, by breeding together FR13A, a low-yield variety that has an allele for flood tolerance, and IR64, a high-yield variety. The scientists sequenced the DNA of these three rice varieties. Suggest the benefit of sequencing the DNA of IR64-Sub1.
After a few generations of breeding, the scientists crossed IR64-Sub1 with IR64. Explain why the scientists crossed IR64-Sub1 with IR64.
Suggest the benefit of sequencing the DNA of IR64-Sub1.
After a few generations of breeding, the scientists crossed IR64-Sub1 with IR64. Explain why the scientists crossed IR64-Sub1 with IR64.
With reference to Fig. 6.2, suggest explanations for the different responses to gibberellin shown by dwarf variety A and dwarf variety B.
Outline the features of a transcription factor such as BZR1.