The MCAT tests your knowledge of subjects, like biology, chemistry, physics, psychology and sociology, as well as your critical analysis and reasoning skills. intimidating as the MCAT may be though, it is an exam that is required by most medical schools—very few to be taken by applicants!
Of all the ways to prepare for the MCAT, reviewing prep questions is one of the best approaches to familiarize yourself with the types of questions that will be asked during the exam, and, it also gives you the chance to apply your knowledge to passage-based questions for which the MCAT is well known for.
Pseudoionone (PSI) is a terpene ketone derived from essential oils with vast applications in pharmaceutical, fragrance and cosmetic industries. PSI is typically produced from the aldol condensation of citral with ketone catalyzed by sodium hydroxide and lithium hydroxide with yields of 60–80%. Various undesired side reactions exist with these homogeneous catalysts such as the self-condensation of acetone and the secondary reactions involving the PSI produced. These homogeneous catalysts are also highly corrosive in nature and require neutralization steps upon reaction completion. Thus, the re-use of the catalyst is not practical.
Selection of a selective catalyst can increase the total yield and also reduce the formation of byproducts. Heterogeneous catalysts are easily separated from the reaction mixture and therefore, can be regenerated and reutilized. These advantages give rise to a more environmentally friendly process.
The importance of PSI encourages researchers to constantly improve the synthetic process. Table 1 shows the recent modifications and improvements that have been accomplished in the last decade to increase the efficiency of PSI production.
Recently, a new PSI derivative, 11,15-dimethylhexadeca-8,10,14-trien-7-one, was reportedly synthesized in the aldol condensation of citral and 2-octanone with sodium ethoxide catalyst. Regrettably, the new PSI derivative is not characterized in the paper mentioned. One of the weaknesses of this experiment is the use of sodium ethoxide where it is typically made by treating sodium metal with ethanol . In addition to being a costly material, sodium also reacts violently in the presence of water or oxidizing agent. Sodium ethoxide, which is usually used in the form of liquid with ethanol, is highly corrosive due to its strong base nature. Apart from that, inorganic salts formed in the neutralization steps upon reaction completion are undesirable for industry.
Amberlyst A-26 OH is a strong base, anionic, macroreticular polymeric resin based on the crosslinked styrene divinylbenzene copolymer containing quaternary ammonium groups. It is highly suitable to serve as a green catalyst. In its solid form, it is nonhazardous and can be used in a heterogeneous catalysis. After a reaction reaches completion, it can be recovered by simple filtration. Furthermore, many researchers have shown that this catalyst can be regenerated with ease using a 1 m NaOH solution.
Reference: An improved method for aldol condensation catalyses by Amberlyst A-26 OH: application in the synthesis of pseudoionone derivative, 11,15-dimethylhexadeca-8,10,14-trien-7-one; Daniel J.W. Chong, Florence H.L. Chong and Jalifah Latip. Green Processing and Synthesis
1. In the reaction of citral with acetone, what is the role of base?
A. Increasing the pH for isolation of product
B. Formation of Carbanion in acetone
C. Formation of Carbanion in Citral
D. Formation of carbocation in acetone
2. With the information provided in the passage, why heterogeneous catalysts are more efficient in catalyzing Aldol condensation reaction?
A. Heterogeneous catalyst is solid while reactants are in liquid phase, therefore separation is easier
B. Heterogeneous catalysts are easy to make
C. Heterogeneous catalysts give overall more yield
D. Both A and C
3. Aldol condensation leads to the formation of which new bond?
Since the discovery of sickle cell disease (SCD) in 1910, enormous strides have been made in the elucidation of the pathogenesis of its protean complications, which has inspired recent advances in targeted molecular therapies. In SCD, a single amino acid substitution in the β-globin chain leads to polymerization of mutant hemoglobin S, impairing erythrocyte rheology and survival. Sickle cell anemia is caused by homozygosity of the beta-S (βS) allele, which differs from the wild-type β-allele by a single nucleotide polymorphism in which GTG is substituted for GAG in the sixth codon of the β-globin gene. This leads to replacement of a hydrophilic glutamic acid residue (Glu) with a hydrophobic valine residue (Val) at the sixth position in the β-globin chain, resulting in a mutated hemoglobin tetramer HbS (α2βs2) in the erythrocytes of individuals with sickle cell anemia.
Over the past 7 decades, scientists have characterized three major pathobiological processes (HbS polymerization, vaso-occlusion, and hemolysis-mediated endothelial dysfunction) that drive clinical disease. A single-nucleotide polymorphism in the β-globin gene leads to substitution of valine for glutamic acid at the sixth position in the β-globin chain. Following deoxygenation, the mutated hemoglobin (HbS) molecules polymerize to form bundles. The polymer bundles result in erythrocyte sickling by increasing cellular rigidity and distort the erythrocyte membrane, which in turn results in impaired rheology of the blood and aggregation of sickle erythrocytes with neutrophils, platelets, and endothelial cells to promote stasis of blood flow, referred to as vaso-occlusion.
Hemoglobin (Hb) polymer bundles also promote hemolysis or lysis of erythrocytes, which releases cell-free Hb into the blood circulation. Oxygenated Hb (Fe2+) promotes endothelial dysfunction by depleting endothelial nitric oxide (NO) reserves to form nitrate (NO3−) and methemoglobin (Fe3+).
Some of the approved or potential therapies prevent HbS polymerization and rescue erythrocyte deformability. Other strategies include allosterically modifying HbS oxygen affinity. In addition to anti-polymerization or anti-sickling therapies, several antiadhesion therapies are approved or being tested.
Prithu Sundd, Mark T. Gladwin and Enrico M. Novelli
1. Sickle cell anemia is an example of which kind of mutation
A. Mismatched pair of DNA bases
B. Point mutation in single nucleotide
C. Lack of formation of alpha helices in hemoglobin
D. Lack of polymerization of mutated hemoglobin HbS
2. According to the passage which of the following describe the pathogenesis of SCD
A. Deoxygenated hemoglobin forms insoluble bundles
B. Erythrocyte cell membrane deformation
C. Release of cell free hemoglobin
D. All of the above
3. From the passage what can be the definition of Vaso-Occulation
A. Sticking of sickle cells with other cells
B. Distortion of cell membranes
C. Generation of reactive oxygen species
D. Block blood flow to the point that tissues become deprived of oxygen.
There are four kind of vision problems. Myopia (Nearsightedness), Hyperopia (Farsightedness), Astigmatism and Presbyopia. In Myopia an elongated eyeball, a thick lens, or rigid or highly curved cornea may cause light that enters your eyes to deposit in front of the retina instead of directly on it. The nearsighted (myopic) eye converges rays from a distant object in front of the retina; thus, they are diverging when they strike the retina, producing a blurry image. This can be caused by the lens of the eye being too powerful or the length of the eye being too great. Difficulties seeing distant objects is the hallmark sign of this problem. Prescription eyewear and refractive surgeries may help correct this error. Concave lenses change the angle of refraction for light rays, so that they converge farther back on the retina.
In Hypermetropia (Farsightedness), as the opposite of myopia, there is an unusually short eyeball and a less curved cornea or thinner lens which directs the received light to the back portion of your retina. The farsighted (hyperopic) eye is unable to converge the rays from a close object by the time they strike the retina, producing blurry close vision. You may have a blurred close-range eyesight yet intact distant vision when this happens.
Correction of nearsightedness requires a diverging lens that compensates for the overconvergence by the eye. The diverging lens produces an image closer to the eye than the object, so that the nearsighted person can see it clearly. This reduces the power of an eye that is too powerful. To determine the spectacle power needed for correction, you must know the person’s far point—that is, you must know the greatest distance at which the person can see clearly. Then the image produced by a spectacle lens must be at this distance or closer for the nearsighted person to be able to see it clearly. It is worth noting that wearing glasses does not change the eye in any way. The eyeglass lens is simply used to create an image of the object at a distance where the nearsighted person can see it clearly.
1. Figure a, b, c respectively; indicate the point in case of:
A. The Hypermetropia eye, the myopic eye and normal eye
B. The normal eye, the myopic eye and Hypermetropia eye
C. The normal eye, the Hypermetropia eye and myopic eye
D. The myopic eye, the normal eye and Hypermetropia eye
2. What type of lens is used to correct myopia?
3. What does farsighted mean?
A. You can see far away well.
B. You can see close up well.
C. You have perfect sight.
D. You are blind.
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Before you begin studying and preparing—and before your do anything else—the most important thing you can do is relax and de-stress! Focus and confidence, as well as plenty of sleep and a healthy lifestyle is key in achieving the best prep routine, as well as the key to acing the MCAT.
You may be asking yourself, and the truth is, it is a taxing exam due to the duration and number of subjects covered… but the difficulty is subjective and can vary depending on how prepared you are! Overall, the MCAT is a notoriously stressful undertaking for students, and many feel that it presents hurdles to specific groups of people, and unfair bias overall. At BeMo, we firmly believe that the MCAT scores do not accurately reflect a students’ ability to practice medicine, nor should it be a considered a fair predictor of their capabilities in general, but nevertheless, the MCAT is still a requirement for many schools. So, in order to best prepare, we recommend you do a few things:
1. How long is the MCAT test?
The MCAT test takes 7.5 hours to complete; it’s a notoriously intense and intimidating exam for this reason, as well as the fact that it covers 7 subject areas.
2. How much time do I need for preparation and studying?
While this can certainly vary between students, it is recommended that you spend several weeks, or, about 3 months preparing for the MCAT. Ideally, you should spend anywhere from 20-60 hours each week studying leading up to the MCAT.
3. What part of my MCAT prep should I do first?
Before you draft up a study schedule or start your practice questions, it’s imperative that you take an MCAT diagnostic test in order to see what your current score is, and decide what you need to study most/determine areas of improvement.
4. Why are MCAT prep questions important to review?
The MCAT is a very long exam that covers a variety of subject areas relevant to medical school and medical programs, including, but not limited to, biology, chemistry and physics. Reviewing prep questions is crucial so you can familiarize yourself with the structure and nature of the potential test questions you’ll face, and allow yourself time to practice applying your knowledge, and reviewing what a suitable, correct answer is!
5. Are there any other tips that can help me with my MCAT prep?
Yes! Ensure that you set a good study schedule once you complete your MCAT diagnostic test and make note of areas that you are struggling with. If you find yourself getting distracted or facing numerous challenges, an MCAT tutor, MCAT prep course, and/or an MCAT prep book may help you improve your ability to focus and properly understand and answer each question! Additionally, it’s important that you review practice questions thoroughly and don’t overwhelm yourself. Take time to rest, work on other tasks, and take care of your health and wellbeing when you aren’t studying!
6. I’m struggling—what should I do?
Do not worry—a lot of students struggle with the MCAT and MCAT prep—and, we at BeMo don’t believe it’s a fair test or accurate depiction of one’s ability to perform and succeed in medical school! Aside from contacting a tutor or searching for a prep course, we highly recommend that if you are struggling with your MCAT prep, you reach out to We’re here to help you with our 1-on-1 preparatory services and we love to help students ace their MCAT!
7. What happens if I get a low score on the MCAT?
Unfortunately, sometimes even with a valiant effort and hours of prep, students can do poorly on the MCAT. Don’t fret, though, because you can exam. Alternately, you may opt to consider one (of few) schools who do not require applicants to take the MCAT.
8. Can I take the MCAT during my application process?
You may know that taking the MCAT is in your near future, but if you’re wondering, you’re not alone! While it is entirely up to you when you take your exam, we strongly advise against students taking the MCAT, or even tackling intensive MCAT prep, during their application process. Your medical school application process is extensive and requires a lot of time and energy, so balancing your application materials and interviews with your MCAT prep and test will surely be overwhelming.