Which of the following steps has not yet been accomplished by scientists studying the origin of life?
a. synthesis of small rna polymers by ribozymes
b. formation of molecular aggregates with selectively permeable membranes
c. formation of protocells that use dna to direct the polymerization of amino acids
d. abiotic synthesis of organic molecules

The correct answer is option c. "formation of protocells that use DNA to direct the polymerization of amino acids".

Explanation:

The polymerization of amino acids is a complex biological function that involves multiple proteins and cofactors working together at different locations in the cell. Even though there are some scientific advances in the production of synthetic protocells (cell like structures made from synthetic particles), the formation of protocells able to synthesize amino acids from DNA directly has not been accomplished.

c) 50% there are four chromosomes. after crossing over, 2 of the four have been changed. that means any gamete has a 2 in 4 chance or 50% chance of receiving the mutated chromosome.