These two events in combination – the binding of the activator and the release of the repressor – allow RNA polymerase to bind strongly to the promoter and give it a clear path for transcription. They lead to strong transcription of the lac operon and production of enzymes needed for lactose utilization.
It is because the males are heterozygous in terms of sex chromosome. They carry one copy of the X chromosome and one copy of the Y chromosome. So, only a single copy of allele is enough to produce the phenotype.
Olivine is a mineral and gabbro is a rock
No they do not. Scientists study it to figure it out why some have it and others do not. It is quite rare, actually. Certain humans are capable of things most would consider strange and not human, such as being able to calculate things at an incredible speed, or an athlete faster than an Olympic medalist.