Each of three botanists made a hypothesis regarding specimens of a par

Question

Each of three botanists made a hypothesis regarding specimens of a particular plant species:

Botanist 1: Any individual specimen possessing the gene for curly stems has either the gene for long roots or the gene for purple flowers, or both. 
 Botanist 2: Any individual specimen possessing the gene for long roots has either the gene for flat leaves or the gene for round seeds, or both. 
 Botanist 3: No individual specimen that possesses either the gene for curly stems or the gene for flat leaves or both has the gene for purple flowers.

The discovery of an individual specimen of the plant species in question having the gene for  __1__  but NOT the gene for  __2__  would show that at least one of the three hypotheses described is incorrect.

Select for  1  and for  2  the characteristics that would most accurately complete the statement, based on the information given. Make only two selections, one in each column.

ID: 700228

KarishmaB · Accepted Answer

As I map my data, I see there is a problem. B1 says curly stems means long roots or purple flowers. But B3 says curly stems or flat leaves cannot have purple flowers. So if a specimen has curly stem but not long roots, as per B1, it must have purple flowers. But as per B3, a specimen with curly stems cannot have purple flowers. Hence if a specimen has curly stem but not long roots, one botanist becomes incorrect. ANSWER 1 - Curly Stems 2 - Long Roots Here are some other TPA discussions: https://youtu.be/CuEUshOOlK0 https://youtu.be/WassWEtmcGo https://youtu.be/K-weMRndUEA https://youtu.be/sOzRtWGu3G0 https://youtu.be/-9i-MmJE8Jg

PS31 · Answer

According to first statement if they have curly stems then they either have long roots or purple flower
According to last statement if they have curly stems then they can't have purple flower
Combining these two, the specimen has only long roots

So if the specimen has curly stems but no long roots then 1st statement will be invalid

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jaky_nguyen · Answer

1st: curly -> long/purple/both
2nd: long -> flat/round/both
3rd: No curly/flat/both -> purple

Base on this: 3rd hypothesis conflicts with 1st on the case curly -> purple. Therefore, one of these Hypotheses or both might be incorrect
1st is incorrect when curly -> NO long OR NO Purple
3rd is incorrect when curly/flat/both -> purple

If blank 1 curly, blank2 NO long, and 3rd is correct NO curly-> purple, then curly -> NO long OR NO Purple => 1st is incorrect

Anonymous · Answer

I'll add my 2 cents on it. Let's denote  curly stems -> cs long roots -> lr purple flowers ->pf   flat leaves -> fl.

Gathering on a table the assumptions of B1,B3 (since they have most elements in common) and we use + for having and - for not having ( see the table below)  we can see that for all 4 elements apart from cs and lr, both botanists agree on having or not having. So, these two (cs,lr) will fill in the blanks.  If it has cs but not lr then the first botanist is mistaken . But also, if it has lr but not cs then the last one is wrong. We choose the first one (the highlighted) because in the statements given the cs is in the  if clause  whereas the lr in the  result clause ?

ScottTargetTestPrep   manasp35   KarishmaB   chetan2u 
  B1   B3 
 cs  + +

fl  - -

pf  + +

lr  + -

Danny134 · Answer

The key is to treat the individual hypotheses as combined information when looking for the correct answer. Since B1 and B3 combined implies that if a plant has curly stems- it will have long roots only.

Hence, if a plant has curly stems but not long roots- that would make hypothese of B1 invalid.

Hence, if a plant has curly stems but not long roots- that would make hypothese of B1 invalid.

Gemmie · Answer

1: If C => P or L

2: If P => F or R

3: If C => not P
....If F => not P

==> 1 and 3 sound conflicting
==> It might be related to whether C and P co-exist

So if the specimen has C
=> Then it has either L or P

(i) If C but not P
=> it must be C + L
=> no contrast with any other statement

(ii) If C but not L
=> it must be C+P
=> Constrast with Botanist 3's statement

PeachSnapple1 · Answer

Any two part questions will have a total of 10 combinations, only some of which make sense. When I counter these kind of questions, instead of thinking to pinpoint an exact pair, I always go through the 10 combinations. It's easier to spot the wrong pair than to spot the right pair right of the bat. This technique allows me to average ~1.5-2 minutes per TPA question.

Botanist 1: Any individual specimen possessing the gene for curly stems has either the gene for long roots or the gene for purple flowers, or both.
Botanist 2: Any individual specimen possessing the gene for long roots has either the gene for flat leaves or the gene for round seeds, or both.
Botanist 3: No individual specimen that possesses either the gene for curly stems or the gene for flat leaves or both has the gene for purple flowers.
The discovery of an individual specimen of the plant species in question having the gene for __1__ but NOT the gene for __2__ would show that  at least one of the three hypotheses described is incorrect .

Here are the 10 combos:
curly stems - flat leaves: not against the hypothesis, as curly stem could have round seed, and not necessarily flat leaves -->  eliminate 
curly stems - long roots:  correct , as we know curly stem can have either long root or purple flowers or both (according to Botanist 1), but according to Botanist 3, curly stem cannot have purple flower. That leaves us with the only choice: curly stem must have long root. And now, if the curly stems don't even have the long root, then that's a big paradox.
curly stems - purple flowers: not against the hypo - it's actually the idea of Botanist 3. -->  eliminate 
curly stems - round seeds: not against the hypothesis, as curly stem could have flat leaves, and not necessarily round seeds -->  eliminate 
and so on...

km0808 · Answer

So if we say that C cannot have LR:

So then:
Botanist 1 says it must have PF

But:
Botanist 2 says it cannot have PF

So then one of them must be wrong

aditsatt · Answer

Hi Karishma,
Thank you for breaking down the solution for us.

Could you please help me understand why "having the gene for Flat Leaves/Round Seeds but NOT Long Roots" would be wrong?

Because this would immediately prove B2 wrong imo, since the plant has to have gene for Long Roots for it to have either Flat Leaves, Round Seeds or both.

Similarly, "having the gene for Long Roots/Purple Flowers but NOT Curly Stems" would immediately prove B1 wrong, since the gene for Curly Stems would have to be there for it to have Long Roots/Purple Flowers/both.

The text doesn't mention the possibilities of the genes due to other alternative reasons.

cheshire · Answer

Botanist 2’s hypothesis (B2)

B2 does not say “If a plant has flat leaves or round seeds, then it must have long roots.” 
 It only forbids “long roots” without at least one of “flat leaves” or “round seeds.” 
 A plant with flat leaves (or round seeds) but without long roots is perfectly compatible with B2, so it does not refute B2.  
To refute B2 you would need to find a plant that does have long roots but has neither flat leaves nor round seeds.

Botanist 1’s hypothesis (B1)

B1 does not say “If a plant has long roots or purple flowers, then it must have curly stems.” 
 A plant with long roots (or purple flowers) but without curly stems is allowed by B1, so it does not refute B1.  
To refute B1 you would need a plant that does have curly stems but has neither long roots nor purple flowers.

Sonatomar · Answer

But the answer is proving the hypothesis, rather than disapproving it.

egmat · Answer

Hi Sonatomar,

I see exactly where this feels backwards, so let me separate two things:  using  the hypotheses and  confirming  them.

When KarishmaB (and others) trace "curly stems but not long roots," they're not agreeing with the botanists - they're doing a  proof by contradiction . The move is:  assume all three hypotheses are true , then see what such a specimen would be forced to look like.

Walk it through:

- Botanist  1 : a curly-stemmed specimen must have  long roots or purple flowers . Since this one has no long roots, it is forced to have  purple flowers .
- Botanist  3 : a curly-stemmed specimen  cannot  have purple flowers.

So the same specimen must have purple flowers  and  must not have them. That's impossible.

Here's the key:  the impossibility isn't confirming the hypotheses - it's the opposite. It means that  if  such a specimen is ever actually discovered in the real world, the three hypotheses  cannot all be correct , because together they forbid that specimen from existing. That's precisely what the blank asks for: a discovery that shows at least one hypothesis is wrong.

Think of it this way - the reasoning only "proves" the specimen can't exist  under  the hypotheses. Reality handing you that specimen breaks the hypotheses, not the specimen.

A tiny parallel to lock it in:

- Rule A: every club member owns a car or a bike (or both).
- Rule B: no club member owns a bike.

Now someone discovers a  member who owns no car . Rule A forces them to own a bike; Rule B forbids a bike. Finding that member doesn't confirm the rules - it shows one of the two rules is false.

Same engine here: the derivation looks like it's "using" the rules, but its punchline is that a real specimen with  curly stems but not long roots  can't coexist with all three - so one botanist is wrong.

Answer: Column 1 = curly stems; Column 2 = long roots

Each of three botanists made a hypothesis regarding specimens of a par

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GMAT Two-part Analysis (TPA) Questions

Each of three botanists made a hypothesis regarding specimens of a par

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