Why do scientists run control experiments and repeat their tests several times?

•in an experiment the control is what the everything is compared to
->this allows the experimenter to determine what the effect of the variable is

•they repeat the tests to ensure precision and accuracy

•human error and inconsistencies effect results
->by repeating the tests they can assure that they have results as free from error as possible

As the pollen tube penetrates the ovule it releases to sperm cells as in gymnosperms The ovule becomes a seed encasing the embryo and endosperm in a seed coat