The doubling time of a type of bacteria is 35 minutes. if every bacterium reproduces, then after 35 minutes a population of 64 bacteria will have grown approximately to what size

Approximately the size of bacteria will grow to 128 bacteria if 64 bacteria will reproduce after 35 minutes. They will only reproduce once in 35 minutes. 
A bacteria will usually reproduce or grow by dividing into two this is called a binary fission. On the above situation, 64 bacteria will reproduce also a 64 bacteria which has the total of 128. 

Mitochondria is the cell organelle that produced the energy that is needed in the body system in form of atp, that is why it is called the power house of the cell. energy is needed by the living organisms to carry out the activities which sustain life.  if the mitochondria is destroyed atp will not be produced. if the mitochondria is destroyed, energy production will stop and the affected living organism will not have the energy to carry out the necessary life processes; this will lead to the death of the organism.