The answer is A most definitely i've looked it up
Answer:
11) A. The optimum pH of an enzyme is 6.6
12) C. A control group
Cell membrane control the entry and exit of the cell . cell membrane even seperate external environment from the internal cell. gates seperate our house from roads , even gate controls entry and exit . in this way cell membrane and gates are similar
Planarians and tapeworms are from Platyhelminthes, which contains flatworms.