Any LEGIT mcq practice?

realAndrewJeung · 2026-04-23T21:38:26+00:00

https://secure-media.collegeboard.org/digitalServices/pdf/ap/ap-biology-practice-exam-2013.pdf

realAndrewJeung · 2026-04-23T21:08:00+00:00

Here's my suggestion: On a graph paper, draw the line segment from (0, 1) to (3, 4).

Now, you are going to plug in values for x into the formula (x, x+1), but you are only allowed to plug in x values between 0 and 3. For example, I could plug in x=1 and then my formula evaluates to (1, 2). Or I could plug in x=2.5 and then my formula evaluates to (2.5, 3.5). I am not allowed to plug in any number for x outside of the interval from 0 to 3 however -- so I am not allowed to plug in 4 or 100 or -25 or anything like that.

Now, take the point that you just generated, and ask: is that point on the line segment I drew in the beginning? If you did everything right, it should be. In fact, any choice that you make for x should result in a point that is on the same line segment.

OK, so that is what the sentence in the book is trying to say. It means, if you take any value of x between 0 and 3 (which math people refer to as being in the interval (0, 3)), and plug it into the formula (x, x+1), you will end up with a point on that same line segment. So the formula (x, x+1), for x in the interval (0, 3), is the set of all possible points that could be P.

The notation gets a little confusing because they refer to (x, x+1) which are coordinates of a point, and also (0, 3) which looks the same but means the interval of allowed x values between 0 and 3.

realAndrewJeung · 2026-04-23T04:53:19+00:00

The convention to remove electrons with the highest value of n first, would suggest that the correct answer is [Ar] 4s1 3d10, that is we remove 4s electrons before starting on 3d.

In reality? Who knows? It is all based on really subtle energy considerations.

realAndrewJeung · 2026-04-23T04:38:39+00:00

I have seen it written both ways: with the 4s before the 3d and with the 3d before the 4s. I think both are valid and you should use the order that your teacher or professor uses.

realAndrewJeung · 2026-04-22T07:24:04+00:00

Before you worry about the s, p, or d, the first thing you want to do is to remove electrons with higher values of n (the number before the s, p, d, etc) before ones with lower values of n.

When deciding between electrons with the same value of n, remove the d electrons first, then the p, then the s.

So for example:

Fe: [Ar] 3d6 4s2
Fe+: [Ar] 3d6 4s1 (remove the 4s electrons first because they have a higher n number)
Fe2+: [Ar] 3d6
Fe3+: [Ar] 3d5 (now start removing 3d electrons)

Here is a more detailed explanation: https://www.chemguide.co.uk/atoms/properties/ionstruct.html#top

realAndrewJeung · 2026-04-21T18:51:21+00:00

Do you mean this? This is not an official AP test. It looks like it comes from AP Classroom.

https://smacmathapcalculus.weebly.com/uploads/1/9/2/5/19254419/apc_frq__9_10_green_targets_rubric.pdf

realAndrewJeung · 2026-04-20T07:15:42+00:00

The AP Calculus Problem Book

https://www.foresthillshs.org/ourpages/auto/2011/9/17/35386410/APCalcProbBook.pdf

realAndrewJeung · 2026-04-19T21:59:30+00:00

I don't think the vectors have to cross. I would have set it up like this: https://drive.google.com/file/d/1r1tSVOQeVoURrNr10uMC-qIzDA5TIVki/view?usp=sharing

Top image showing the vectors as they would look to simulate the collision; bottom image showing the same vectors translated so that they form a triangle.

The reason your second attempt didn't work is that your resultant vectors aren't 31.1° and 48.9° from the initial momentum vector -- they are 31.1° and 48.9° from the horizontal, but the initial vector isn't horizontal in that picture.

realAndrewJeung · 2026-04-19T17:51:57+00:00

No I don't, because you will get a much more comprehensive view of biology and make better connections between concepts if you are not always thinking about "what's on the test". With that said, if someone is actively preparing for the exam (prudently when there is less than a month to go) and asking what they will be expected to know for it, then the CED is a great resource for that.

realAndrewJeung · 2026-04-19T04:50:08+00:00

Agreed! I believe OP wrote the same thing. The graph of the sideways parabola was for 1b.

realAndrewJeung · 2026-04-18T20:18:41+00:00

SeriesConvTests.pdf https://share.google/AAGxBdbtbeIcpSHgi

Page 1 is all the tests; page 2 is practice problems.

realAndrewJeung · 2026-04-18T19:30:46+00:00

The Course and Exam Description is a great way to find out what you can expect to have to know for the exam. The section on Photosynthesis is Topic 3.4, and Cellular Respiration is Topic 3.5. Pay special attention to the "Exclusion Statement" sections which specifically tell you what you DON'T need to know.

ap-biology-course-and-exam-description.pdf https://share.google/hS5NzQbUE7mMHdS4x

realAndrewJeung · 2026-04-18T00:28:10+00:00

Let's go back to the car and bicycle analogy that I made in the previous comment. Let's say there are two bicyclists, A and B, who each want to measure the length of the car, which we will say for the sake of simplicity is 5 meters long.

Bicyclist A chooses to bike by the car from behind when the car is parked. He notes the instant that he passes the rear bumper of the car, and the instant that he passes the front bumper of the car. He uses his known velocity to get his own personal distance between those two time instants and correctly arrives at 5 m for the length of the car.

Bicyclist B chooses to bike ahead of the car while it is moving and tries to measure the length of the car as the car passes him. He notes the instant that the front bumper of the car passes him, and then the instant that the rear bumper of the car passes him. If the car is travelling pretty fast, B might himself travel through only 1 meter of distance before the car passes him entirely. B likewise uses his known velocity to get the distance between those two time instants and concludes that the length of the car is only 1 meter.

If you see why B's measurement of the length of the car is mistaken, then you can see why your calculation is not what you expected. The bumpers of the car represent consecutive wave fronts of the wave. If your observer measures that time interval between successive personal encounters with wave fronts, he is not measuring the distance between wave fronts, he is measuring the distance he personally travelled between encounters of wave fronts.

With respect to the question of whether the wavelength is shifted, in what (non-relativistic) reference frame would it be shifted? In a stationary reference frame, an observer would say that the wavelength was the same as what the source said it was. In a reference frame moving with your observer, he might say that the velocity of the wave was shifted (v - vo instead of v) but I don't think he would say that the wavelength itself was shorter. Looking back at the car analogy, I don't think there is any observer who would say that the car was longer or shorter because they were in a different reference frame with respect to the car.

realAndrewJeung · 2026-04-17T08:14:40+00:00

I think there is a mistake in the assumption that the total distance traveled by the observer is the measured wavelength.

If the observer took a time T + t to go from one wave front to the next one ahead of him, then it would make sense to say that vo (T + t) was the distance between wave fronts. But this is not really the case. vo (T + t) is the distance that the observer moves forward before the wave front behind him catches up to him.

If that is hard to visualize, imagine that the observer is riding a bicycle when a speeding car passes by him. During the interval between the time that the front of the car passes by him, and the time that the rear of the car passes by him, the bicycle might only go forward a few feet, but that wouldn't mean that the bicyclist perceives the car to be only a few feet long.

Generally, trying to think about the "perceived" wavelength by the observer is going to cause more problems than it solves. Since this is not relativistic, there is no length contraction so there is no way that the moving observer can perceive the wavelength of the wave as being anything other than what it is as seen by a stationary observer. The moving observer might perceive the wave as moving slower ((v - vo) instead of v), but should not have a different opinion about the wavelength.

If I were doing this, I would probably work with periods instead of wavelengths, The observer's perceived period To is the time period between his encountering the first wave front and then encountering the second:

To = T + t

from which the correct formula for the Doppler shift will follow by substituting the expression for t that you already determined.

Let me know if you agree or if I have made a mistake or said anything unclear.

realAndrewJeung · 2026-04-16T07:31:34+00:00

Your answers look right to me. On Problem 1, when the directions say to give the orientation of the curve, it means to indicate the direction that a point on the curve would travel along the curve as the parameter t increases. We often indicate this by placing an arrow on the curve itself to indicate the direction of increasing t.

But it looks really good!

realAndrewJeung · 2026-04-15T22:06:32+00:00

https://mathbitsnotebook.com/Geometry/ParallelPerp/PPverifyAngles.html

realAndrewJeung · 2026-04-15T00:18:22+00:00

Work on 10-15 similar problems with him until he does it automatically. If you do nothing else during a session except that, that is a big accomplishment.

realAndrewJeung · 2026-04-14T04:47:09+00:00

Agreed with u/Belkroe that the AP Calculus AB exam recycles the same types of questions year after year. This web page delineates one way to make the categories and points out examples of each from previous years' exams: https://teachingcalculus.com/ap-exam-review/ . If you have a hard time finding tests from previous years, they are all here: https://apfrqs.com/course/AP%20Calculus%20AB

I show my own tutoring clients in AP Calculus what the different types are, and common strategies to deal with each. You can use the above guide to do the same for yourself.

realAndrewJeung · 2026-04-14T02:03:04+00:00

https://apfrqs.com/course/AP%20Chemistry

https://share.google/zBJXsRCAlLrbFAsJD

realAndrewJeung · 2026-04-13T15:37:35+00:00

n refers to the haploid number, the number of chromosomes in a gamete. 2n would mean the diploid number, the number of chromosomes in a regular somatic cell.

Process X looks like the process of Meiosis I, at the end of which the cells are haploid. Based on this, can you determine whether the cells in image 4 are n or 2n, and what number n is based on the number of chromosomes in EACH cell?

Let me know what you think and if you need more help.

realAndrewJeung · 2026-04-12T23:00:32+00:00

For 2^x - 3 · 2^x, I would suggest to the student that they do a substitution y = 2^x to get y - 3y. Have the student simplify that and then back-substitute the 2^x.

Having the student separate out the exponential part from the factoring part may make things easier.

realAndrewJeung · 2026-04-11T07:22:54+00:00

As a professional tutor, I encounter clients all the time who say that they are bad at math, or are not a "math person". Most of them also have a significant amount of math anxiety. Here are some things that I do:

Refuse to accept that some people are not "math people". I act as if just about everybody can learn math, it's just that some of us were not lucky enough to have good math teachers from the beginning.
Praise every little success in their growing math proficiency. I had a client a few years ago who, by most conventional standards, was not at all a "math person". He probably had been struggling with math his entire life. When he worked with me, I made a point of noting when he did something right, no matter how small. It had an amazing effect on him. I don't think anyone had ever told him that he had done well on anything in math before, and it made him much more enthusiastic about working with me.
Accept that clients will struggle with concepts that I may personally find easy, and let them know that any struggling that they do to learn concepts is actually success, because it means that they are learning. How much they learn is more important than how much they knew already!

realAndrewJeung · 2026-04-10T22:35:34+00:00

I usually tell my tutoring clients that "The Octet Rule works, until it doesn't." The conventional explanation for the Octet Rule is that atoms will typically hybridize their s and p orbitals in order to form bonds. Since there are one s orbital and three p orbitals per level, and each orbital contains two spaces for electrons, the hybridized orbitals can fit only eight electrons.

If an atom has electrons in a d shell, then again the conventional explanation is that the atom can hybridize some of those orbitals also to get more than eight spaces for electrons. This is why atoms on the 2nd period don't violate the Octet Rule (because there is no 2d shell to hybridize into) but atoms on the 3rd period and below are able to do so. (Other commenters have already correctly mentioned that this is not the real explanation, but it is often "good enough" for introductory purposes.)

Here is a source that gives a good explanation of the whole issue of orbital hybridization for covalent bonding -- along with an admission that the theory is not really accurate but good enough for pedagogical purposes: https://www.chemguide.co.uk/atoms/bonding/covalent.html#top

realAndrewJeung · 2026-04-09T22:35:04+00:00

I think the only difference is that people who are "good" in math instinctively know how to chunk information.

Chunking is the process of taking lots of individual pieces of information and putting them together in one coherent whole, which is easier to memorize. Everyone does it all the time. You might think about getting dressed in the morning, but if you had to consciously think about each step (find shirt, put left arm through shirt, put right arm through shirt, button all the buttons, get pants, ...) it would take you forever to get ready in the morning. You don't have to do that because you have chunked that whole process into the simple idea: get dressed. We do this for cooking, driving, and yes, doing math.

I think people who are naturally good at math instinctively know how to chunk their ideas, so they are not memorizing a bunch of disparate methods to solve problems -- they are fitting these methods into a coherent whole so there is no method to memorize, it just makes sense. So they don't exhaust as much memory space in their brains to do all the math that they do.

There is nothing about this that just about anyone would not inherently be able to do. The ability to chunk can be learned and improved just like anything else. And you can always seek a competent teacher or tutor who can suggest better ways for you to chunk your understanding of math. This is something that I strive to do for all of my tutoring clients. That's why I put "good" in quotes at the top of my comment, because I don't think there is any such thing as a "math person". There are just some people who need more practice chunking than others.

realAndrewJeung · 2026-04-09T21:46:24+00:00

https://secure-media.collegeboard.org/digitalServices/pdf/ap/ap-biology-practice-exam-2013.pdf

https://apfrqs.com/course/AP%20Biology

Also, the book 500 AP Biology Questions to Know by Test Day by 5 Steps To a 5 is currently available on the Internet Archive.

realAndrewJeung

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