Answer:
Mechanical isolation
Explanation:
mechanical isolation is a form of prezygotic reproductive barrier, whereby similar species organisms become isolated and unable to successfully interbreed with each other to form zygote, as a result of incompatibility of their reproductive organ or structure, which prevents them from copulating. As a result of this, both species become separated as there is no gene flow between both.
The two species of juniper can be said to be kept separate by <em>mechanical isolation</em>, due to the differences and incompatibility of their reproductive structure.
All of these birds share a common ancestor
Hope i helped :3
Answer:
The gene for beta-galactosidase turns off.
Explanation:
The gene that codifies the beta-galactosidase enzyme is part of the <em>lac</em> operon, which also contains two other genes that produce enzymes involved in the metabolization of lactose.
Between glucose and lactose, the bacteria will preferentially use glucose as an energy source. On the other hand, lactose is a dimer, and thus a series of enzymes are needed to process lactose before its use as an energy source.
If there is no lactose present, the genes contained inside this operon are turned off (the operon is repressed).