Certain species of fish swim in large clusters called schools

Question

Certain species of fish swim in large clusters called schools, whose function is not entirely understood. Experiments have shown that individual fish, when removed from a school, demonstrate higher heart rates than those found withing the school. Fish may experience stress at being separated from fellow members of their species, but an alternative explanation is that, for hydrodynamic reasons, swimming alone requires more physical exertion.

Which of the following, if discovered in an experiment, would support one of the two hypotheses and undermine the other?

Which of the following,if discovered in an experiment,would support one of the two hypotheses and undermine the other?

A. When a school of fish is made to swim in turbulent condition,the heart rate of each individual fish increases.
B. When individual fish are isolated from their school but are permitted to swim in close proximity to others members of their species,their heart rates remain normal.
C. When a school of fish is threatened by a predator,the heart rates of the fish within it will remain steady,while the heart rates of individual fish will increase significantly.
D. When individual fish are removed from a school,they demonstrate higher heart rates than types of fish that do not normally swim in schools.
E. When a school of fish is threatened by a predator,the fish within it will demonstrate higher heart rates than individual fish isolated from their schools.

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Senthil1981 · Answer

There is one fact and are 2 hypothesis to explain the fact.
Fact/conclusion : Fish has higher heart rate when isolated than when in School
Hypothesis 1: Isolation from their fellow members of the species causes Stress leading to higher heart rate
Hypothesis 2: Isolation demands more physical exertion than when in School.

Let's look at the choices and how to support or refute.

A. When a school of fish is made to swim in turbulent condition,the heart rate of each individual fish increases.
 Does not support or refute either hypothesis.

B. When individual fish are isolated from their school but are permitted to swim in close proximity to others members of their species,their heart rates remain normal.
 Supports Hypothesis 2 and Refutes 1 by stating "other members" instead of "fellow members"

C. When a school of fish is threatened by a predator,the heart rates of the fish within it will remain steady,while the heart rates of individual fish will increase significantly.
 Reiterates the conclusion,but neither support nor refutes any of the hypothesis.

D. When individual fish are removed from a school,they demonstrate higher heart rates than types of fish that do not normally swim in schools.
 Reiterates the conclusion,but neither support nor refutes any of the hypothesis.

E. When a school of fish is threatened by a predator,the fish within it will demonstrate higher heart rates than individual fish isolated from their schools.
 Out of scope

narmadadhruv · Answer

Certain species of fish swim in large clusters called schools,whose function is not entirely understood.Experiments have shown that individual fish,when removed from a school,demonstrate higher heart rates than those found withing the school. Fish may experience stress at being separated  from fellow members of their species,but an alternative explanation is that,for hydrodynamic reasons, swimming alone requires more physical exertion .
Which of the following,if discovered in an experiment,would support one of the two hypotheses and undermine the other?

A. When a school of fish is made to swim in turbulent condition,the heart rate of each individual fish increases.  effect of turbulent water is out of scope, we are only concerned with effect on fish separated from a school vis-a-vis hydrodynamic OR stress level. 
B. When individual fish are isolated from their school but are permitted to swim in close proximity to others members of their species,their heart rates remain normal.  again out of scope, since there is an ambiguity on effect of close proximity on fish; does it have a hydrodynamic effect or doest it effect stress level due to isolation? 
C. When a school of fish is threatened by a predator,the heart rates of the fish within it will remain steady,while the heart rates of individual fish will increase significantly.  this means anxiety/stress levels for fishes in the school is steady whereas for fishes out of the school it is not - correlates with the bold part mentioned above 
D. When individual fish are removed from a school,they demonstrate higher heart rates than types of fish that do not normally swim in schools.  it is not the comparison we are looking for. This one compares different types of fishes, whereas we are looking for effect of separation on the same fish 
E. When a school of fish is threatened by a predator,the fish within it will demonstrate higher heart rates than individual fish isolated from their schools.  this does not correlate with the statement in bold, in fact this is the reverse of C and a trick to confuse and delay us from giving the right answer, more practise of these question types will make us reject this option in <5 secs.

khitindra · Answer

I would go With Option B. The reasoning behind the answer choice B is that

When individual fish are isolated from their school but are permitted to swim in close proximity to others members of their species, the fishes are not swimming alone. They have other members of their species as well. So less energy is exerted while swimming.

A,C,D,E options are out of context.

abhishekdadarwal2009 · Answer

Certain species of fish swim in large clusters called schools,whose function is not entirely understood.Experiments have shown that individual fish,when removed from a school,demonstrate higher heart rates than those found withing the school.Fish may experience stress at being separated from fellow members of their species,but an alternative explanation is that,for hydrodynamic reasons,swimming alone requires more physical exertion.
Which of the following,if discovered in an experiment,would support one of the two hypotheses and undermine the other?

A. When a school of fish is made to swim in turbulent condition,the heart rate of each individual fish increases.  this does not support nay claim.
B . When individual fish are isolated from their school but are permitted to swim in close proximity to others members of their species,their heart rates remain normal.  Correct because when the fish swims along other fishes of same species then they dont experience higher heart rate.
 C. When a school of fish is threatened by a predator,the heart rates of the fish within it will remain steady,while the heart rates of individual fish will increase significantly. 
 D. When individual fish are removed from a school,they demonstrate higher heart rates than types of fish that do not normally swim in schools. 
 E. When a school of fish is threatened by a predator,the fish within it will demonstrate higher heart rates than individual fish isolated from their schools.

Rishovnits · Answer

Hi can you please tell me how does it support hypothesis 2?

TaN1213 · Answer

Hello,

Premise:
Within the group -- normal heartbeat rate
Isolated from group -- faster heartbeat rate
Reasons: 
1. Isolating the fish might have caused stress
2. Physical exertion due to hydrodynamic reasons
 
Aim : to support one and undermine the other

Assume Salmon fishes form schools. Now you are isolating one salmon fish from the school. It is expected that the heart beat rate increases. But now you have placed this Salmon fish near other fishes such as jelly fish. Presence of jelly fishes balances the hydrodynamics and the heart rate of that Salmon fish remains normal, as opposed to the expected heart rate increase. 
This supports reason 2 and shows that reason 1 is not valid as the heart rate does not increase despite the isolation.

Hope that makes sense.

Idonije · Answer

I still don't understand the answer to this question. How is it B? feels like everyone is guessing.

guddo · Answer

Certain species of fish swim in large clusters called schools, whose function is not entirely understood. Experiments have shown that individual fish, when removed from a school, demonstrate higher heart rates than those found withing the school. Fish may experience stress at being separated from fellow members of their species, but an alternative explanation is that, for hydrodynamic reasons, swimming alone requires more physical exertion.

Which of the following, if discovered in an experiment, would support one of the two hypotheses and undermine the other?

Which of the following, if discovered in an experiment, would support one of the two hypotheses and undermine the other?

The two hypotheses are different. One says the higher heart rate is caused by stress from being separated from other fish. The other says it is caused by the greater physical effort of swimming alone.  So the right answer must separate social isolation from swimming effort .

A. When a school of fish is made to swim in turbulent condition, the heart rate of each individual fish increases.

This shows that physical difficulty can raise heart rate, but it does not explain the original case of fish removed from a school.

B. When individual fish are isolated from their school but are permitted to swim in close proximity to others members of their species, their heart rates remain normal.

This is correct. If the fish are not in their original school but are still near other fish, and their heart rates remain normal, that supports the stress hypothesis: being near other fish prevents the stress response. It undermines the swimming-effort hypothesis because the fish are still not swimming as part of a normal school, yet their heart rates are normal.

C. When a school of fish is threatened by a predator, the heart rates of the fish within it will remain steady, while the heart rates of individual fish will increase significantly.

This adds a predator threat, which changes the situation. It does not cleanly test whether the original higher heart rate is due to separation stress or swimming effort.

D. When individual fish are removed from a school, they demonstrate higher heart rates than types of fish that do not normally swim in schools.

This does not clearly choose between the two hypotheses. Schooling fish might be more stressed when alone, or they might simply be less efficient when swimming alone.

E. When a school of fish is threatened by a predator, the fish within it will demonstrate higher heart rates than individual fish isolated from their schools.

This does not support either original explanation well. It focuses on predator threat, not the effect of being separated from the school.

Answer: (B)

egmat · Answer

Hi Idonije,

I get why the earlier replies felt like guessing. Things like "it says  other  members, not  fellow  members" don't really explain the logic. Let me give you the actual mechanism.

Start with the two competing explanations for why an isolated fish has a faster heart rate:

-  Hypothesis 1 (stress):  being  separated from its own school  upsets the fish.
-  Hypothesis 2 (exertion):  swimming alone  is physically harder for hydrodynamic reasons.

The trick is that in the original experiment,  both things happen at once  - the removed fish is both separated  and  swimming alone. So you can't tell which one is raising the heart rate. To split them, you need an experiment that  changes one factor but not the other .

What B actually does

In B, the fish is  "isolated from their school but permitted to swim in close proximity to other members of their species."  Look at the two factors separately:

-  Still separated from its own school  - if stress were the cause, the heart rate  should still be high .
-  No longer swimming alone  (other fish nearby restore the hydrodynamic benefit) - if exertion were the cause, the heart rate  should drop back to normal .

The result: heart rate  stays normal . That outcome matches the exertion prediction and  contradicts  the stress prediction. So B  supports Hypothesis 2 and undermines Hypothesis 1 . That's exactly what the question asks for - and it's not a guess; it's a controlled comparison.

Why this beats the predator choices

C and E add a  predator  - a brand-new stressor that wasn't in either hypothesis. They never separate "alone vs. together" from "stressed vs. calm," so they can't tell the two apart. D compares different  species , which is irrelevant. Only B isolates one variable.

Quick way to lock it in:  picture testing whether a plant wilts from  too little water  or  too little light . You'd keep it watered and just remove the light. If it still wilts, light wasn't the problem. B does the same move - it removes only the "swimming alone" factor and watches what happens.

Answer: B

Certain species of fish swim in large clusters called schools

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Certain species of fish swim in large clusters called schools

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