What is the experiment called in which all the features of each experimental group are exactly the same, except for the independent variable?

i think it's called a controlled group

answer by yourhope:

answer is

human impact on the environment can be seen in the deterioration of the !

: )

the unequal cytoplasmic division that  results  in  one egg  and three polar bodies ensures that a fertilized  egg has  ample nutrients  forits journey  to  the uterus.