What is involved in muscle contraction?
A. Myofibrils in the muscle shorten and lengthen to make the
muscle contract and extend.
B. Actin and myosin come in and out of the cell to make it thicker
or thinner which changes its length.
C. The gap junctions between the cells pull them closer together
which shortens the muscle.
D. The extra nuclei trigger nerves to stiffen the muscles and make
them shorter.

Drag the tiles to the correct boxes to complete the pairs. match the nitrogenous base of dna with its complement.

Lactase is essential for digesting lactose in milk. this enzyme is specific for this sugar. why? molecules and active sites vary in size; only properly sized molecules can fit.there is a precise compatibility between the active site and the lactose molecule.specificity refers to the action of the enzyme, such as hydrolysis, and relatively few molecules can be hydrolyzed.reaction-specific enzymes assume a fit by folding around the most numerous substrate molecules.

Which was not a reason why canals were built in florida