AAMC CBT5 and 5R OFFICIAL Q&A

[Vihsadas]

This is the official Q&A thread for AAMC CBT5 and 5R.

Please post ONLY questions pertaining to AAMC CBT5 and 5R.
Out of respect for people who may not have completed the other exams, do not post questions or material from any other AAMC exam.

Please see this thread for the rules of order before you post.

Good luck on your MCAT!

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[dmplz707]

"and excretion is accomplished by hundreds of threadlike malpighian tubules that collect waste fluids, depositing them in the posterior intestine."

Wouldn't this be similar to the bladder? The bladder also collects waste fluids from the kidney..could someone please help me in reasoning this out? Thanks a lot!

 

[whiteshadodw]

"and excretion is accomplished by hundreds of threadlike malpighian tubules that collect waste fluids, depositing them in the posterior intestine."

Wouldn't this be similar to the bladder? The bladder also collects waste fluids from the kidney..could someone please help me in reasoning this out? Thanks a lot!

the kidney exclusively 'collects waste fluids' or rather it filters fluids. when you can narrow it down to two, like kidney and bladder, you have to ask yourself which answer is best. the bladder STORES urine, and the kidney just recollects ions, and sugars and gets rid of what water is left along with some urea.

 

[dmplz707]

i took the AAMC 5 in between 6 and 7, 6/5/7, and i got 42/36/42 lol
so yea, i did well, But i definitely took a hit on 5, mostly because of the science sections.

as far as that question everyone is asking about, the answer explains it well, in the beginning of the paragraph they talk about how it was infectious, so its DEFINITELY III... but the problem stated was that they couldn't find anything, so I is false. II is false because it is stated that it could not be grown AND because its the opposite of what a microbial pathogen should do

For this question, the passage states;

"Viewing identical samples with the electron microscope, however, did reveal spherically shaped objects (later identified as virions) interspersed among certain white blood cells."

Wouldn't this be consistent with Statement I;

I. Suspicious objects were found in blood samples from ill patients

on the last question of this passage? Thanks a lot guys!

 

[dmplz707]

Sorry guys I have another question from the BS section. On question 11 Passage II, I narrowed it down to Endoplasmic Reticulum vs Plasma Membrane and I ended up choosing the ER. The answer is the Plasma Membrane but wouldn't the ER be a viable choice as well?

 

[samvillian]

For this question, the passage states;

"Viewing identical samples with the electron microscope, however, did reveal spherically shaped objects (later identified as virions) interspersed among certain white blood cells."

Wouldn't this be consistent with Statement I;

I. Suspicious objects were found in blood samples from ill patients

on the last question of this passage? Thanks a lot guys!

My rationale for crossing out I was that:

They didn't find anything BEFORE coming to the conclusion that it was a virion, but only found that out AFTER knowing what they were dealing with. So that is why it can't be I, because it didn't happen in that order.

 

[Joker88]

#14 According to Equation 1, the concentration of the polymer with respect to the [HPO4^2-] is:

C. 1/n[HPO4^2-]

I understand why its "n" and not "n^2" but why is it 1/n. How come A. n[HPO4^2-] isnt right?


#19 The best materials to use as scintillators are nearly transparent to the wavelength of the light they emit. THis characteristic is important because:

A. It minimizes the reabsorption of the light

I put C (it maximizes the amount of light produced). Im guessing the scintillator doesnt control how much light is released? Its based on how much energy is intially absorbed during the excitiation? Does the scintillator play no part in the excitation? So the material only affects how much light leaves it to be collected by the photomultiplier...Is this logic correct?

 

[Joker88]

I don't understand why the answer is A? the explanation says that it has to be opposite direction to make the standing wave....
I am not following.....
Can anyone help? Thanks a lot.

For a given laser-cavity mode, the standing-wave pattern within a laser cavity can be viewed as a
superposition of two traveling waves. Their amplitudes and directions are described by which of the
following?
A) Equal amplitudes; opposite directions
B) Equal amplitudes; same direction
C) Different amplitudes; same direction
D) Different amplitudes; opposite directions

Standing waves viewed as a superposition travel in opposite directions with an equal amplitude. It makes it look like theyre not moving but they really are. Also, take a look at that diagram in the passage. Thats the standing wave theyre referring to.

 

[Joker88]

help anyone??

 

[liveoak]

joker, the concentration of the polymer should NOT change w/more initial moles.

Therefore, 1/n * n/1 = 1

that's why we must multiply the concentration of [HPO4] by 1/N to convert it to a constant value of ONE. (which is what the concentration of the polymer must stay as)

 

[dmplz707]

Sorry guys I have another question from the BS section. On question 11 Passage II, I narrowed it down to Endoplasmic Reticulum vs Plasma Membrane and I ended up choosing the ER. The answer is the Plasma Membrane but wouldn't the ER be a viable choice as well?

Could someone provide their own reasoning for this following question that I have quoted above? Thanks.

 

[Joker88]

thanks for the help!

dmplz,

hopefully im thinking of the same question as you are. They're looking for a defect in the receptor from what i remember. The receptor is going to be placed on the plasma membrane. Now of the choices given the only one that is most likely to have a defect is going to be the plasma membrane. The ER wont display the receptor. It may not be a clear question but remember to look for the best answer

 

[DrDotooMuch]

Sorry guys I have another question from the BS section. On question 11 Passage II, I narrowed it down to Endoplasmic Reticulum vs Plasma Membrane and I ended up choosing the ER. The answer is the Plasma Membrane but wouldn't the ER be a viable choice as well?

Don't trip. I got you covered. Its not the ER. Why would it be the ER. If there is no receptor on the membrane. The only thing your sure is that the non-mutated rats have the receptor and the mutated rats don't have them. Where are receptors?.... on the plasma membrane.

 

[DrDotooMuch]

I don't understand why the answer is A? the explanation says that it has to be opposite direction to make the standing wave....
I am not following.....
Can anyone help? Thanks a lot.

For a given laser-cavity mode, the standing-wave pattern within a laser cavity can be viewed as a
superposition of two traveling waves. Their amplitudes and directions are described by which of the
following?
A) Equal amplitudes; opposite directions
B) Equal amplitudes; same direction
C) Different amplitudes; same direction
D) Different amplitudes; opposite directions

I help you. When I did this test. I immediately eliminated C and D because if they had different amplitudes you would have one of those funny waves that have different peaks and troughs all over the wavelength (a non sin wave). This wave looks like a normal wave (from the tube picture) so the amplitudes must be equal so you don't have a really funny wave and you have a wave that looks like a normal sin wave. It must be in opposite direction according to superposition principle. Hope this helps.

 

[PlatinumPenny]

I just took AAMC #5 VR section just for practice. Half of the questions I got wrong came from that Picasso passage. Just came here to vent!

 

[fingerscrossedd]

I just took AAMC #5 VR section just for practice. Half of the questions I got wrong came from that Picasso passage. Just came here to vent!

man oh man, do i feel you on the Picasso passage! I got owned on that one

 

[BilalL]

I just took AAMC #5 VR section just for practice. Half of the questions I got wrong came from that Picasso passage. Just came here to vent!

Yup I got only 2 questions wrong in the rest of the passages and missed 4 questions in the Picasso passage. But I got my usual avg on verbal, so I guess they made the rest of the verbal much easier to compensate for the Picasso.

 

[yangsc]

okay, i get that you need to add both acid and heat to dehydrate/create an anhydride, but why does the order matter? here is the question: http://i.imgur.com/aGMhU.png

 

[notbobtrustme]

okay, i get that you need to add both acid and heat to dehydrate/create an anhydride, but why does the order matter? here is the question: http://i.imgur.com/aGMhU.png

acid protonates the carbonyl which allows for nucelophillic attack on the carbonyl carbon. heating restores the carbonyl.

when you heat first, you aren't driving any reaction forward. the acid is needed to protonate the carbonyl then heating drives the formation of the anhydride

 

[SysBio]

I have a couple of Q's for the: Biology Section - AAMC 5R (full length)

In passage 1, last question:
wouldn't you assume clonal deletion occurs in the lymph nodes, similar to clonal selection?

In passage 7, 2nd last question:
I dont understand the difference between longeivity of a species vs longeivity of an individual....answer D (I, II, and III) seems right to me

 

[YouNeverKnow22]

Also did anyone miss the one about the speed of the ocean wave because the question was ambiguous.

If ocean waves strike the shore every 3.0 s and the horizontal distance between adjacent crests and troughs is 1.0 m, what is the average speed of the waves?

This could mean either the distance between adjacent troughs (one wavelenth) is 1m (like I thought it meant) or it could mean 0.5 wavelength. Why can't they just make it clear by says "the distance between AN adjacent peak and trough is 1m". I feel like they do a ****ty job with ambiguity.

I still don't understand this, why is the wavelength 2?
edit nevermind--I'm guessing it's because crest-crest=2 because crest-trough is 1 (half the distance), stupid miss on my part

 

[YouNeverKnow22]

#14 According to Equation 1, the concentration of the polymer with respect to the [HPO4^2-] is:

C. 1/n[HPO4^2-]

I understand why its "n" and not "n^2" but why is it 1/n. How come A. n[HPO4^2-] isnt right?


#19 The best materials to use as scintillators are nearly transparent to the wavelength of the light they emit. THis characteristic is important because:

A. It minimizes the reabsorption of the light

I put C (it maximizes the amount of light produced). Im guessing the scintillator doesnt control how much light is released? Its based on how much energy is intially absorbed during the excitiation? Does the scintillator play no part in the excitation? So the material only affects how much light leaves it to be collected by the photomultiplier...Is this logic correct?

can anyone help with these two?

 

[EnginrTheFuture]

can anyone help with these two?

The second one has to do with resorption of light emitted by the scintillator, not the absorption of the particle you are trying to detect.

A scintillator is a piece of material that is good at absorbing incoming radiation/decay products like gamma rays. Upon "capturing" that incoming radiation, it emits a photon of light that is often times in the visible range. This light is the scintillator telling you "hey, I got hit by what your're looking for but can't see with your eyes normally". A counter can take each little flash of light emitted by this material and count them for you (As opposed to Rutherford who had grad students get bombarded by radiation and strain the hell out of their eyes to count little flashes of light). This tells you how many original particles struck the scintillating material over a given period of time.

The question asks about the absorption not of the radiation (which you want a high absorption of this obviously), but rather the absorption of the light the scintillating material emits within itself when it captures the radiation. If every time it captured a particle it emitted a photon of light that got nowhere before getting reabsorbed, the detector or grd student will never get any counts.

You want to maximize the absorption of the incoming particles/decay product of interest by the scintillator.

You want to minimize the absorption of the light that the scintillator emits to tell you "hey I got hit by the particle you're looking for"

 

[09ine]

Question 130 BS

Arthropods as a Taxon unit, are considered successful because:
I. there are numerous species
II. many individuals have relatively long life spans
III. there are aquatic, terrestrial and flying species.

I put down all 3 because the first sentence says:

"evolutionary successful in terms of species LONGEVITY, diversity, and variety of ecological niches"

Does not RELATIVELY long life spans = longevity?

 

[Dasypus]

I'm afraid you fell into their little trap Species longevity ≠ longevity of individuals.

For instance, a species of beetle could have been around for millions of years, though no individual lived more than six months. Very long-lived species, made up of very short-lived animals.

 

[09ine]

I'm afraid you fell into their little trap Species longevity ≠ longevity of individuals.

For instance, a species of beetle could have been around for millions of years, though no individual lived more than six months. Very long-lived species, made up of very short-lived animals.

Oh damn, I can't believe I fell for that one then.

 

[qw098]

Hypothetical Question:

For the picture shown down below...

What if the question read:

"As the pressure applied to the sample of water at 0.01 Celsius is increased from 1.0 torr to 200 atm at constant temperature the:"

A) Vapor will become a solid then a liquid
B) Vapor will become a liquid

The reason I ask this, is because according to my modified question up above... we would be going through the triple point, and isn't the triple point the point where all three phases can co-exist? So would the vapor become a solid, and then a liquid, or just become a liquid?

Thanks!

 

[nickelbackfan]

Physical sciences question #14

According to Equation 1, the concentration of the polymer with respect to [HPO42–] is:
A) n[HPO42–].
B) n2[HPO42–].
C) (1/n)[HPO42–].
D) (1/n2)[HPO42–].
According to the balanced coefficients in Equation 1, each time one molecule of the polymer (CP)n is formed, there also are n hydrogen phosphate ions HPO4-2 produced. Thus, the concentration of (CP)n must be 1/n times the concentration of the HPO4-2. The correct response is C.
I just don't understand the correlation at all with respect to the n. Someone? Anyone?

Can someone please explain this? I still don't understand it.

If you have N moles of HPO42- for 1 mole of CP, would that make it a 1:n ratio? I chose A

 

[rjosh33]

Can someone please explain this? I still don't understand it.

If you have N moles of HPO42- for 1 mole of CP, would that make it a 1:n ratio? I chose A

Yes, the ratio is 1:n. But don't just stop there. Set up a proportions equality.

That is, 1/n = [(CP)n] / [HPO4]. Then, solve for [(CP)n] by multiplying over [HPO4].

You then get [(CP)n] = (1/n) ([HPO4]), which is the correct answer.

 

[nickelbackfan]

Yes, the ratio is 1:n. But don't just stop there. Set up a proportions equality.

That is, 1/n = [(CP)n] / [HPO4]. Then, solve for [(CP)n] by multiplying over [HPO4].

You then get [(CP)n] = (1/n) ([HPO4]), which is the correct answer.

Ok thank you I think I understand now. I think my problem was with a basic understanding of ratios and proportions. So when one says there is a 1:2 ratio of A to B, then that means A/B=1/2 right?

 

[rjosh33]

Ok thank you I think I understand now. I think my problem was with a basic understanding of ratios and proportions. So when one says there is a 1:2 ratio of A to B, then that means A/B=1/2 right?

Exactly. Also, it's easy to get mixed up with variables, so if possible I usually try to insert (easy) numbers as a check.

Using the above problem as an example, if 1 mole of (CP)n also results in 4 moles of HPO4 ions, then [(CP)n] = 1/4[HPO4], which is consistent with the correct answer.

 

[argama]

Nvm wrong thread, sorry

 

[smaziz]

Does anyone know why on question #120, the answer is
C: attack at the carbonyl carbon atom by the lone pair of nitrogen
and not B: protonation of the carbonyl oxygen by the hydrogen atom of water?

Thanks!!

 

[carboxylase]

#46

A certain laser has only one mode of oscillation. Which of the following are properties of the light it emits?
I. it is monochromatic
II. it is coherent
III. it is difuse

Answer: I and II.

Part of the explanation says: a laser with one mode produces light at a single frequency (monochromatic).

How do we know this?

 

[asf503]

#46

A certain laser has only one mode of oscillation. Which of the following are properties of the light it emits?
I. it is monochromatic
II. it is coherent
III. it is difuse

Answer: I and II.

Part of the explanation says: a laser with one mode produces light at a single frequency (monochromatic).

How do we know this?

The answer stem addressed this:

"A certain laser only has one mode of oscillation."


When a light source has only one wave of oscillation, it's basically telling you that that light is only spitting out one wavelength of light- i.e. that light source is only emitting a monochromatic light (mono means one)

 

[Shams al Deen]

There were three killer questions on the PS section of this test:
- #6 about relative concentrations of CFCs and O2. They somehow expected you to realize that the CFC produced a chlorine radical which acted as a catalyst and therefore CFC was present in a catalytic amount. I was really confident with my wrong answer of 2 eq. But this turned out to be a very hard question.

-#24 about which gas evolves when a strip of Cu placed in solution of HNO3. I put H2, but answer was NO and I'm still not completely sure why that is. Another very difficult question.

#52 about a nearsighted person and what corrective lens he would require. Not a big fan of optics and this one was unlike other optics problems I've done. I didn't know we had to be that familiar with the human eye.

To me, it seems like every MCAT section will have about 2 to 4 crazy questions like these and getting a 14 or 15 comes down to either superior science knowledge past the pre-reqs OR great luck.

BS had a few crazy one as well.
-#110 the last question on the weird protozoa with macro/micronuclei passage. They were asking about the F1 generation resulting from a heterozygous and homozygous strain. I could not figure out how to even approach this question.

#117 about reversing the reaction...How was I supposed to know what heating did? I'm not great with Ochem, but I don't remember seeing this in the review books.

Feels like its a lot easier to make the careless mistakes with BS tho because you just want the exam to be done by the time you get to that section.

 

[circulus vitios]

#117 about reversing the reaction...How was I supposed to know what heating did? I'm not great with Ochem, but I don't remember seeing this in the review books.

Feels like its a lot easier to make the careless mistakes with BS tho because you just want the exam to be done by the time you get to that section.

This question got me, too. The equation in the passage doesn't mention any heating so I guess you're supposed to assume that it's favorable as written. Reversing a favorable reaction is unfavorable so it would require additional energy through heating, I guess.

BTW, **** everything about the protozoan passage.

 

[Bru]

Ugh. One word: Picasso.

11/11/11. Not horrible but I i kept falling for/missing little wording traps in the questions. Felt less straight-forward the 3,4. A fair amount of specific knowledge questions as well. On the plus side, I'll never forget what an imide is.

 

[Patassa]

Picasso, you're an @sshole. I missed 4 on that passage alone. That's never happened to me before, I got an 11 because of that jerk.


The Cu, HNO3 problem makes me want to punch a baby.

 

[451617]

The second one has to do with resorption of light emitted by the scintillator, not the absorption of the particle you are trying to detect.

A scintillator is a piece of material that is good at absorbing incoming radiation/decay products like gamma rays. Upon "capturing" that incoming radiation, it emits a photon of light that is often times in the visible range. This light is the scintillator telling you "hey, I got hit by what your're looking for but can't see with your eyes normally". A counter can take each little flash of light emitted by this material and count them for you (As opposed to Rutherford who had grad students get bombarded by radiation and strain the hell out of their eyes to count little flashes of light). This tells you how many original particles struck the scintillating material over a given period of time.

The question asks about the absorption not of the radiation (which you want a high absorption of this obviously), but rather the absorption of the light the scintillating material emits within itself when it captures the radiation. If every time it captured a particle it emitted a photon of light that got nowhere before getting reabsorbed, the detector or grd student will never get any counts.

You want to maximize the absorption of the incoming particles/decay product of interest by the scintillator.

You want to minimize the absorption of the light that the scintillator emits to tell you "hey I got hit by the particle you're looking for"

get reply - thanks!

 

[gettheleadout]

What I missed and care to comment on:

PS #9 - I agree with everyone who says this is ambiguous; "adjacent crests and troughs" - does that mean adjacent crests and adjacent troughs, or an adjacent crest and trough? They should have just said "an adjacent crest and trough."

PS #24 - Cu and HNO3. So this is hard because, as the explanation said, H2(g) is plausible. I agree most with an earlier thread response mentioning that it should have occurred in water as well if H+ were being reduced. Comparing the electronegativities of N vs H seems like a more difficult way of determining that.

VR #79 - I actually got this one right, but I think it sucks. Their explanation for why A isn't correct is a joke, and is the kind of statement I would expect to be the answer to a question asking "which part of the passage isn't supported by [anything]." Pathetic.

BS #105 - How is DNA self-replicating? DNA needs a multitude of enzymes to act on it to replicate. Furthermore, they explain "nonlinear" as being incorrect because "all nucleic acids are a linear arrangement of component nucleotides," but when genes are described as linear or nonlinear, that distinction only makes sense in the context of the overall strand, i.e. linear like eukaryotic chromosomes, or nonlinear like circular prokaryotic chromosomes.

 

[Neutral]

Alright I've read through this entire thread, and while some people have addressed this question, I haven't seen too many answers that really flesh it out.

I'm referring to question 24, PS section and it is as follows:

"When a strip of Cu is placed into H2O (l), no change is observed. However, when a strip of Cu is placed into a solution of HNO3 (aq), a gas evolves. What is the most likely identity of the gas?"

I, like many others, chose H2. The correct answer was NO.

How does this problem work? Does Cu form a bond to HNO3? Or Does Cu simply lose electrons to become oxidized, while HNO3 picks them up to be reduced? So we would have Cu 2+ and... HNO32-? If nitrogen picks up those electrons it would have 8 from its bonds to oxygen, picking up another two would im guessing make one of those bonds go to a lone pair on the oxygen to make nitrogen have 3 sigma bonds to oxygen, a lone pair, and 2 O's with -1 charges?

I don't really know what I'm doing when it comes to this problem so any help would be greatly appreciated!

 

[pm1]

At first, I had the right answer. I had multiplied the deltaS value by the number of moles.

However, the units on the answer choices J/(mol K) made me go back and not multiply by mols.

Shouldn't the units of the answer be J/K since we were already supposed to multiply by number of mols???

Thanks!

 

[Heday]

At first, I had the right answer. I had multiplied the deltaS value by the number of moles.

However, the units on the answer choices J/(mol K) made me go back and not multiply by mols.

Shouldn't the units of the answer be J/K since we were already supposed to multiply by number of mols???

Thanks!

They're asking for the standard entropy change of the reaction, so no, the units would not be in the form of J/K. Think of the reaction at a more basic level so see if the answer you get makes sense. You go from 2 moles of gas to 3 moles of gas. So entropy should increase (be positive). The way you did it, you would get 205-238.8=-33.8 which does not make sense. Entropy should be positive; your only choices are B and D based solely on the fact that entropy is increasing in the system. The only way to get +33.8 would be to do Reactants minus Products, which makes no sense. DeltaG, DeltaH, DeltaS... pretty much every equation we use is always products minus reactants.

If you just did products minus reactants (with and without using moles), you'd get either 137.4 or -33.8, however you know that deltaS is positive, so D is only logical choice even if units don't make sense to you.

 

[pm1]

Hmmm.. I see. Yea, it wouldn't make sense for the answer to be a negative value.
Thank you!!!

 

[Heday]

Alright I've read through this entire thread, and while some people have addressed this question, I haven't seen too many answers that really flesh it out.

I'm referring to question 24, PS section and it is as follows:

"When a strip of Cu is placed into H2O (l), no change is observed. However, when a strip of Cu is placed into a solution of HNO3 (aq), a gas evolves. What is the most likely identity of the gas?"

I, like many others, chose H2. The correct answer was NO.

How does this problem work? Does Cu form a bond to HNO3? Or Does Cu simply lose electrons to become oxidized, while HNO3 picks them up to be reduced? So we would have Cu 2+ and... HNO32-? If nitrogen picks up those electrons it would have 8 from its bonds to oxygen, picking up another two would im guessing make one of those bonds go to a lone pair on the oxygen to make nitrogen have 3 sigma bonds to oxygen, a lone pair, and 2 O's with -1 charges?

I don't really know what I'm doing when it comes to this problem so any help would be greatly appreciated!

I'll take a stab.

Background info: most of us probably thoughr of that Zinc and HCl reaction producing ZnCl2 and H2. It made sense to us back then, it's a redox reaction. Well HCl is a strong acid so it dissociates to H+ and Cl-. The Zn then reduces the H+ and that's how you end up with H2 gas and ZnCl2. Zn has the option of reducing H+ or Cl-, however notice that Chlorine already has a negative charge (it's got enough electrons).

In Cu and HNO3, the same thing happens, we have the acid dissociating into H+ and NO3-, with the Cu ready to reduce. Most people would say "H+" is reduced since it has a positive charge, BUT we need to look at the lewis structure for NO3-.

Notice how nitrogen has a positive charge in all the resonance structures? So now we're trying to decide who wants to be reduced more, N+ or H+? Think about the electronegativities of the two atoms. We KNOW that F, O, and N are more electronegative than H because these atoms can engage in hydrogen bonding. Electronegativity is the tendency is attract electrons to itself. So N+ seems to be the clear winner in terms of who will be getting the electrons. [Electronegativity is 3.04 for N and 2.20 for H]

CO2 does not make sense as there is no C. O3 does not make sense since all the oxygens have negative charges. It's a choice between N and H. The reaction with Zn and HCl is easier to deal with because we don't have two electron deficient atoms to choose between. However, what would you expect from Zn and HNO3?

 

[FeinMS]

Man, I took 5R and it was a tricky one! I thought I would do worse, but the score was the same compared to AAMC 3 and 4. It seems like their scale is pretty reliable.

 

[onedirection]

The PS Section
The laser passage

A certain laser has only one mode of oscillation, which of the following are properties of lgiht it emits?

The answer was I and II
But isn't monochromatic light impossible?

 

[monkeyvokes]

The PS Section
The laser passage

A certain laser has only one mode of oscillation, which of the following are properties of lgiht it emits?

The answer was I and II
But isn't monochromatic light impossible?

Why do you say that?

 

[onedirection]

Why do you say that?

I remember reading a PS passage once that said it is impossible to have monochromatic light


Also I wasn't sure about that one question

In a mating of two Tetrahymena strains that are homozygous in their macronuclei and heterozygous in their micronuclei for a recessive gene, what percentage of the F1 generation will express the recessive phenotype

How did you know that you simply had to do a cross between two heterozygotes?

 

[FeinMS]

I remember reading a PS passage once that said it is impossible to have monochromatic light


Also I wasn't sure about that one question

In a mating of two Tetrahymena strains that are homozygous in their macronuclei and heterozygous in their micronuclei for a recessive gene, what percentage of the F1 generation will express the recessive phenotype

How did you know that you simply had to do a cross between two heterozygotes?

The passage tells you that the macronuclei is responsible for gene expression and micronuclei become macronuclei. So genes in micronuclei end up macronuclei to be expressed.