What determines the physical change form of a substance​

Which of the following statements is true of enzymes? a)they dont provide an active site for substrates to bind in a reaction b)they act on a specific type of substrate in a reaction c)they unusable after a reaction d)they change shape after a reaction

Aflame cell is at the end of each tubule of the nephridium malpighian tubules kidneys none of the above

If a strand of dna has 35% thymine. what is the percentage of cytosine, adenine, guanine?