The phylogenetic tree is commonly used by biologists to study evolutionary relationships between organisms and their ancestors. To add up, it is a diagram that branches the "phylogeny" of a single organism which could be very significant and determining on how genetically different or similar they are to their ancestors.
The answer to the question is the letter "A" Breakdown glucose.
The function of beta-galactosidase is to break down glucose. This beta-galactosidase is also commonly called "Beta-gal". This enzyme breaks down the glycosidic bond, it also includes carbohydrates that contain glucose.
The SI system or metric system is the most commonly used system of measurement around and hence makes it more applicable around the world than the english SOM