A galaxy contains stars, gas, and dust. This matter must be held together or the galaxy will break apart. What is responsible for holding the stars, gas and dust together in a galaxy? Group of answer choices

gravity

friction

light

Hemoglobin is a proton that carries oxygen around your body what is hemoglobin made from

Using meiosis, the sporophyte produces spores that are .

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.