Manipulated Variable:The speed working on maths problems
Responding Variable: The group that use¬ using a calculator
Controlled Variable:The same maths quetions
Answer:
In the nucleus of each cell, the DNA molecule is packaged into thread-like structures called chromosomes. Each chromosome is made up of DNA tightly coiled many times around proteins called histones that support its structure.
Http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0072434/
There is a website with some info. Hope it helps! :)
