Blueprint Diagnostic Bio/BioChem Discrete Explanations

Session 279

We are covering the first set of discrete questions in the bio/biochem section. Get this half-length test for free with a free account at Blueprint MCAT.

We’re joined by George from Blueprint MCAT. If you would like to follow along on YouTube, go to premed.tv.

Listen to this podcast episode with the player above, or keep reading for the highlights and takeaway points.

[02:35] Shifting Your Mindset When You Get to Discrete Questions

The biggest concern students have in the science sections is the content. And for the discrete questions, content matters. And so, either you know it or you don’t.

In terms of approach, you just have to decide. For instance, you read the question, and if you don’t know this, just move on. It’s not even a question to flag because if you really don’t have any idea what it is then you will just end up spending more time on it and it won’t give you the answer.

[04:15] Question 16

Which of the following will cause a blood pH of 8.2?

A.Decreased O2 concentration

B.Decreased tidal volume

C.Increased H2O concentration

D.Increased respiratory rate

Thought Process:

If you paraphrase this question, you actually want to know what causes alkalosis.

The key here is to remember that higher CO2 in your blood will make your blood more acidic. It’s a bicarb buffer. Protons plus bicarb makes carbonic acid, (H2CO3}. It makes water (H2O) and CO2. So there’s the spectrum.

And if you think about it, more CO2 will ultimately push towards more protons, so more CO2 in the blood will make it more acidic.

Alkalosis and acidosis are two states, and there are two mechanisms involved here. It’s either respiratory or metabolic. Respiratory means it’s at the level of the lungs. Metabolic means it’s at the level of the kidneys.

All this is saying is that there’s an imbalance in this chemical equation which is the bicarbonate buffer. Either you have too much or too little bicarb, or too much or too little carbon dioxide.

And so, if you want it to be more basic, you have to have too little CO2 in your blood. And that can be done by blowing it off through increased respiratory rate.

If you’re hyperventilating, you’re breathing really quickly, and you’re getting rid of all your CO2 levels in your blood will cause the acid levels to fall. That is why the pH increases. Hence, an increased respiratory rate will cause respiratory alkalosis.

Looking at the other choices:

A – Oxygen concentration has no impact on pH. So this is out.

B – Tidal volume means the amount of volume that you breathe normally. And if you’re decreasing your tidal volume, then you’re not getting enough CO2 out.

C – Water is a solvent and it’s neutral. It’s neither acidic nor basic so it doesn’t change the pH at all.

Correct Answer: D

[14:53] Question 17

Patients with excess fat are more likely to require larger therapeutic doses of which vitamin?

A.Vitamin B1

B.Vitamin C

C.Vitamin D

D.Vitamin B3

Thought Process:

If you paraphrase this question: Patients with excess fat need larger doses of what vitamin? Now, based on stored knowledge, the fat-soluble vitamins are A, D, E, and K. And the only fat-soluble vitamin above is Vitamin D.

If we ingest a regular dose of a fat-soluble vitamin, that’s going to dissolve our fat stores. All the other vitamins in the other answer choices are water-soluble vitamins. In that case, it would have no interaction with fat so it wouldn’t make a difference.

Hence, vitamin D is the correct answer here.

Correct Answer: C

[17:54] Question 18

Chitin’s flexibility and strength make it favorable as a biodegradable surgical thread. All of the following describe the portion of a chitin molecule shown below EXCEPT:

A.carbohydrate.

B.polypeptide.

C.disaccharide.

D.polymer.

Thought Process:

This is an “except question” so if you paraphrase this question, which of the answer choices is not part of the chitin molecule? And so, which one has nothing to do with surgical threading?

Answer choices A and C are both sugars and so we can eliminate these two. Polymers are made up of monomers which are made up of monosaccharides or simple sugars. And each individual sugar either looks like a six-membered ring or a six-carbon light chain, when you flatten it out into a Fischer projection. And it’s a polymer because again, you see multiple units attached together.

A polypeptide is a protein chain, which is a bunch of amino acids. Ultimately, when we look for proteins, we want to look for the classic carboxyl group attached to an R-group. And we don’t see that in the diagram above. And so, the correct answer would be B.

Correct Answer: B

[23:42] How to Stop That Negative Self-Talk

When you actually take your first step, that’s when you start to see progress. And so, take it one step at a time.

Focus on One Skill at a Time

Instead of telling yourself that you’re too slow on CARS, focus on the strategies. Focus on each one of these strategies one at a time. Every time you approach a passage, just think of how you’re going to work on one skill – and one skill only.

Maybe, work on identifying the tone words first. Then in your next passage, practice looking at transition words to see how ideas relate. You’re going to highlight “in contrast to” or “furthermore” or “on the other hand.” Pay attention to these words, so that when you’re asked a question about relationships, you already know how this stuff fits together.

You might miss the other three or four questions, but that’s okay because you’re going to get this question.

Done is Better Than Perfect

Compartmentalize things, make them step by step, take that big goal, and break it down into little things one step at a time. That’s how you can keep that motivation because you will have that progress to motivate you.

“Done is better than perfect. Some progress is better than no progress.” Click To Tweet

If you stack that over time, build those reflective habits, that thought process, and that confidence, by the day it actually matters, it’s going to pay dividends. And so, keep up your good work, keep your mindset open, have a growth mindset, and learn from your mistakes, and it’ll all pay off in the end.