The requirements for becoming a Jonin are not at all the requirements for becoming a Chunin. The explanation for that is simply- the chain of command.
Genin follow the orders of everyone. They are, unless otherwise specialized, the grunts of the ninja world. Every major office in any hidden village will have at least ten genin assigned to it for various purposes, be it cleaning, generalized assistance, or filing- and so on. The Cypher Corps, for example, has no more than a company of genin at a time; their job is to fetch, carry, and for the most part, mind the higher ranked members of the Corps. The Medical Corps has very nearly a brigade of genin whose duties include everything from nursing to maintenance on medical equipment.
Chunin are better than genin- they're generally more experienced, smarter, stronger, and have the responsibility to adapt their orders to situations if they should change. Chunin are able to work with a team; they are also able to work on their own. They have some skill in information gathering and in resisting interrogation; they can survive in enemy territory for a small period of time; they can, for the most part, judge the skill and power of their enemy and determine if the correct course of action should be to engage in or retreat from battle. Chunin follow orders; chunin obey the directives of a plan.
Jonin give the orders. Jonin make the plans. Jonin are, generally speaking, as high as a ninja can publically go in their chain of command. The next rank up is the new rank of Sanin- originally referring to the Dentetsu no Sanin, it now means, in essence, "a ninja with the skill, knowledge, and power of three". It is higher than jonin but lower than Kage, Kage being the highest there is.
The Chunin Exam is a three part test, composed of an intelligence gathering portion, a survival and retrieval portion, and a battle portion. Each section is meant to weed out the genin that are not ready for the responsibilities for being a chunin.
The Jonin Exam is a five part test. Three components of the test are almost identical to the Chunin Exams. However, there are two that are not at all the same. The first is a political portion- Jonin are always, always promoted inside their home village. Prospective jonin are required to have the backing of two different jonin to even attempt the test; securing the backing of a full jonin is, for potential jonin, a test of political acumen. Securing the backing of a jonin three man team, or two man cell, is generally the best plan. The final component is not known to any potential jonin, but is known to all current jonin.
Uchiha Shisui is an interesting young man. He graduated the Konoha academy at the age of eleven, with a score that stuck him in the middle of the class. His highest scores were in Intel, Traps and Evasion, Genjutsu, Taijutsu, and Stealth. He became a chunin at thirteen, and went into ANBU after he became known for his shunsuin. He's specialized in Assasination and Sabotage, and is actually retiring from ANBU after a miraculous full year of missions. Most saboteurs don't live past six months. He's well-liked by his peers, and the general ANBU consensus is that he should be put out into the general rotation while he's still human. He's gained the backing of Combat Cell 20, composed of Maito Gai and Hamaki Mimura; Combat Cell 20 specializes in Heavy Combat and Assault, and has not been fielded since the public treaty with Iwa.
Uchiha Itachi is no less interesting a young man. He graduated the Konoha academy at the age of ten, first of his class- the best of his generation. He had high scores overall, which made his specialization as a Field Medic all the more unique. He apprenticed under Senju Tsunade, and after a year of being a genin, he became both a fully-vetted Medic and a chunin, and went into ANBU as a medic. His mission record shows an impressive level of skill, not just in medical techniques, but with genjutsu and kenjutsu. He's struck terror into the hearts of new recruits, old hands, and Captains alike, and has petitioned several times to start an ANBU specific branch of the Medical Corps. He has the backing of Team Minato, composed of Uchiha Obito, his cousin- also known as The Great Thief; Nohara Rin, a senior medic- also known as The Gentle Death; and Hatake Kakashi, an assault and heavy combat specialist- also known as the White Death.
Iga Raiko is the oldest of her sisters, and graduated at the age of ten, second of her class of kunoichi, third overall. Her scores were well rounded, and her specialization as a Long-distance Heavy Support ninja would make little sense without referencing her psychological profile. While her teamwork is exemplary, Iga Raiko prefers to keep a long distance between herself and the world around her, making her specialization in kyujutsu a logical decision on her part. She became a chunin a year after her induction to the Genin Corps and assignment to the Oinin Corps. She excels in tracking, stealth, and silent take-downs, which is surprising considering her weapon of choice, and her reliance on the color red to differentiate her from her sisters. Further, it is noted that while her bow and arrows are her main method of fighting, she is quite skilled in the use of twin butterfly blades, and the Iga Clan style of Yama-Hitsuji Ken. She is nicknamed "Akachou", and is generally considered the smartest of her sisters due to her habit of trouncing the Nara head and his heir in Go. She has the backing of the currently active Ino-Shika-Chou trio, who have always specialized in Capture, Assasination, and Sabotage; the current generation of the trio has a very good, very clean record of success.
Iga Kirara is the oddest of her sisters. It is noted in her file that the only times she ever actually physically attended the academy was during the entrance ceremony, during year end exams, and during the final exam. She graduated the academy first in her class of kunoichi and second in her class overall. During her tenure as a chunin, Iga-san has been known to throw herself off of tall structures- both natural and man-made. She claims it is a form of training, and as she has passed all of her psychological evaluations, there is little that can be done to dispute her claims. The Iga clan's sealed genjutsu-ninjutsu technique known as "Razor Whirlwind" is a specialty of hers. She also uses a style of taijutsu that focuses on aerial leg techniques. She is nicknamed "Aochou" for her over-large uchikake, which she is never seen publically without; it's long, furisode-style sleeves give her the profile of a butterfly. Its winter-pattern of embroidered white bamboo on sky blue ground painted with darker blue bamboo wax resist, which she wears in all seasons, has gained her the reputation of being an eccentric. She specializes in Espionage, Assassination, and Tactical Explosives. She has the backing of Team 18, consisting of Inuzuka Tsume, Aburame Shibi, and Hyuuga Hizashi. While Team 18 has not been fielded in it's entirety since the Second World War, it still has the highest rate of mission completion for all teams specializing in Tracking, Hunting, and Retrieval.
Iga Yayoi is the prospective head of the Iga clan. Refer to the Iga entry in the Clan files for more information on the rules of succession within the Iga clan. She graduated third in her class of kunoichi, third overall. She has been apprenticed under Senju Tsunade since she became a genin, and is currently the senior apprentice under her; refer to the files on Uchiha Itachi, Nanashi Shizune. She is known for using senbon and bo shuriken with exclusive and lethal accuracy. She is also known for being one of the best genjutsu users in any generation, much less her own; the only challenger she may have for the mastery of the skill is Yuuhi Kurenai. Uchiha Itachi, while known to be an able and slippery user of genjutsu, has admitted that Iga Yayoi outstrips his skill by a large margin. She is well liked by her peers, and has incapacitated the entire active roster of ANBU at least once for, in her words, "Medical Concerns". Her usual target is Neko, who has shown a marked lack of personal concern when applied to medical matters. She has incapacitated Neko no less than thirty times. She has not been reprimanded for this, as her methods have never been the same twice, Neko has not lodged a complaint, and Neko always does need medical treatment before Iga Yayoi forces the issue. She is nicknamed "Kiichou", not because of her prolific use of Daiken, a common poison that is always bright yellow in its base state, but because of her genuinely sunny, happy disposition. Iga Yayoi specializes in Psychological Medicine, and has the most field experience in its use. She has the backing of Combat Cell 4, composed of Yuuhi Kurenai and Uroko Kurama, the so called "Mind Break Twins". No record exists of their being fielded, as publically having a team dedicated to Infiltration, Retrieval, and Assassination is not plausibly deniable in the event of… unfortunate circumstances.
The files are very dry reading, but they shed light on what can, and can't, be determined by an impartial watcher. I know that Iga Yayoi and Uchiha Itachi have something between them- some sweet, delicate thing, just now on the cusp of blooming. I know that Iga Raiko is, for lack of a better phrase, the dumbass of her sisters. I know that Iga Kirara is significantly stranger than can be described on paper. I know that Uchiha Shisui feels inferior to his cousins and his housemates- that's why he pushed himself so hard. I know that Uchiha Itachi became a medic because he's a genuine pacifist.
I know that these next Jonin exams are going to be the most interesting I've gotten to preside over. Hell, I might even pass those jumped up little shits.
Kushina's rubbing off on me…