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# Biological functions of many plants and animals vary in

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Manager
Joined: 17 Jul 2008
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Biological functions of many plants and animals vary in [#permalink]

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18 Jul 2008, 01:33
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72. Biological functions of many plants and animals vary in cycles that are repeated every 24 hours. It is tempting to suppose that alteration in the intensity of incident light is the stimulus that controls these daily biological rhythms. But there is much evidence to contradict this hypothesis.

Which of the following, if known, is evidence that contradicts the hypothesis stated in lines 2-5 above?

(A) Human body temperature varies throughout the
day, with the maximum occurring in the late afternoon and the minimum in the morning.
(B) While some animals, such as the robin, are
more active during the day, others, such as mice, show greater activity at night
(C) When people move from one time zone to another,their biological rhythms adjust in a matter of days to the periods of sunlight and darkness in the new zone.
(D) Certain single-cell plants display daily
biological rhythms even when the part of the cell containing the nucleus is removed.
(E) Even when exposed to constant light intensity around the clock, some algae display rates of photosynthesis that are much greater during daylight hours than at night.

Can anyone explain the logic of the questions and answers behind it?
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Senior Manager
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18 Jul 2008, 02:21
I think the answer is E.

Constant light is applied, therefore the animals' function should be constant, but E says that the animals' function changes.
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18 Jul 2008, 06:41
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Doesn't it explain that the livings actions' change is related with light therefore related with timing?

The official answer is E, yet about the logic I did not get anything. In E it explains algea is effected by sunlight so it does show many reactions in daylight than night. So if the question asks us to undermine not support the conclusion. There has to lie another logic.

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23 Jul 2008, 16:56
Got this one wrong. Wanted to bump up the thread for others to argue! So, please share your thoughts not just the answer
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23 Jul 2008, 17:34
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Stated Hypothesis: Intensity of Incident light has direct relation to the biological rhythms.

The answer choice that weakens the hypothesis will introduce facts that varying intensity also produces the same rhythms effect or same light intensity produces varying rhythms.

(A) Human body temperature varies throughout the day, with the maximum occurring in the late afternoon and the minimum in the morning. [ Yes, supports the hypothesis – eliminate it]

(B) While some animals, such as the robin, are more active during the day, others, such as mice, show greater activity at night [ Direct or inverse relation – no effect]

(C) When people move from one time zone to another, their biological rhythms adjust in a matter of days to the periods of sunlight and darkness in the new zone. [Irrelevant – When biological rhythms get adjusted – eliminate it]

(D) Certain single-cell plants display daily biological rhythms even when the part of the cell containing the nucleus is removed. [irrelevant – eliminate it]

(E) Even when exposed to constant light intensity around the clock, some algae display rates of photosynthesis that are much greater during daylight hours than at night. [Hold it]

Manager
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Re: Biological functions of many plants and animals vary in [#permalink]

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21 Apr 2012, 00:56
Is this a question of Cause and Effect Relationship? If yes, then does answer choice E state that there is an alternate cause to the effect that is hypothesized?
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Manager
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Re: Biological functions of many plants and animals vary in [#permalink]

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21 Apr 2012, 11:05
perfectstranger wrote:
72. Biological functions of many plants and animals vary in cycles that are repeated every 24 hours. It is tempting to suppose that alteration in the intensity of incident light is the stimulus that controls these daily biological rhythms. But there is much evidence to contradict this hypothesis.

Which of the following, if known, is evidence that contradicts the hypothesis stated in lines 2-5 above?

(A) Human body temperature varies throughout the
day, with the maximum occurring in the late afternoon and the minimum in the morning.
(B) While some animals, such as the robin, are
more active during the day, others, such as mice, show greater activity at night
(C) When people move from one time zone to another,their biological rhythms adjust in a matter of days to the periods of sunlight and darkness in the new zone.
(D) Certain single-cell plants display daily
biological rhythms even when the part of the cell containing the nucleus is removed.
(E) Even when exposed to constant light intensity around the clock, some algae display rates of photosynthesis that are much greater during daylight hours than at night.

Can anyone explain the logic of the questions and answers behind it?

Answer E is the best choice. E indicates there is no impact of variations in the sunlight on the rates of photosynthesis performed by algae.
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Joined: 26 May 2012
Posts: 21
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GMAT Date: 09-17-2012
Re: Biological functions of many plants and animals vary in [#permalink]

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17 Feb 2013, 21:24
perfectstranger wrote:
72. Biological functions of many plants and animals vary in cycles that are repeated every 24 hours. It is tempting to suppose that alteration in the intensity of incident light is the stimulus that controls these daily biological rhythms. But there is much evidence to contradict this hypothesis.

Which of the following, if known, is evidence that contradicts the hypothesis stated in lines 2-5 above?

(A) Human body temperature varies throughout the
day, with the maximum occurring in the late afternoon and the minimum in the morning.
(B) While some animals, such as the robin, are
more active during the day, others, such as mice, show greater activity at night
(C) When people move from one time zone to another,their biological rhythms adjust in a matter of days to the periods of sunlight and darkness in the new zone.
(D) Certain single-cell plants display daily
biological rhythms even when the part of the cell containing the nucleus is removed.
(E) Even when exposed to constant light intensity around the clock, some algae display rates of photosynthesis that are much greater during daylight hours than at night.

Can anyone explain the logic of the questions and answers behind it?

But E compares rates of photosynthesis in the day and night. Further E states that in constant light, the photosynthesis is greater than at night, thus light does have an effect, which IMO does not contradict the conclusion.

It is obvious that I am missing something vital here.
Senior Manager
Joined: 07 Nov 2012
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Schools: LBS '14 (A)
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Re: Biological functions of many plants and animals vary in [#permalink]

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18 Feb 2013, 01:59
Hi - I agree.

E is not the correct answer. It supports the conclusion that light is not the key thing that causes creatures to distinguish between day and night...

James
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Re: Biological functions of many plants and animals vary in [#permalink]

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18 Feb 2013, 03:13
plumber250 wrote:
Hi - I agree.

E is not the correct answer. It supports the conclusion that light is not the key thing that causes creatures to distinguish between day and night...

James

Hi James,

But the OA is E. Sometimes I wonder about the accuracy of CR's reasoning for the OAs.
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Re: Biological functions of many plants and animals vary in [#permalink]

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18 Feb 2013, 03:53
Can we see the Reasoning behind the OA?
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Re: Biological functions of many plants and animals vary in [#permalink]

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18 Feb 2013, 04:06
plumber250 wrote:
Can we see the Reasoning behind the OA?

Situation:
Biological rhythms of many plans and animals work in 24 hr cycles. The alteration of the intensity of light is thought to control these cycles.

Reasoning:
What evidence the hypothesis that light is the controlling stimulus?
Look for an example demonstrating that the intensity of light cannot be the controlling stimulus of the 24 hr cycle. Algae exposed to a constant intensity of light throughout the 24 hr cycle nevertheless exhibit a far greater activity of biological functions during daylight hours than at night. The ex. of algae thus contradicts the hypothesis.
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Re: Biological functions of many plants and animals vary in [#permalink]

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18 Feb 2013, 04:12
Right,

I think I get it, the key issue is the phrase 'in lines 2-5' but then in the printed passage it is not clear what those are.

I and others assumed that it refers to the overall conclusion of the argument.

In fact 'lines 2-5' must be the section that talks about the initial hypothesis.

A 'cut and paste' issue from another source.....
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Re: Biological functions of many plants and animals vary in [#permalink]

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18 Feb 2013, 04:21
plumber250 wrote:
Right,

I think I get it, the key issue is the phrase 'in lines 2-5' but then in the printed passage it is not clear what those are.

I and others assumed that it refers to the overall conclusion of the argument.

In fact 'lines 2-5' must be the section that talks about the initial hypothesis.

A 'cut and paste' issue from another source.....

Sorry mate I dont follow where you're coming from.
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Re: Biological functions of many plants and animals vary in [#permalink]

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18 Feb 2013, 04:24
If the passage was written like this (rough cut and paste)

72. Biological functions of many plants and animals
vary in cycles that are repeated every 24 hours. It is
temptingto suppose that alteration in the intensity
of incident light is the stimulus that controls
these daily biological rhythms.

But there is much evidence to contradict this hypothesis.

The relevant section ('in lines 2-5') is highlighted.

So if you look at it like that, then the official answer explanation makes perfect sense
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Re: Biological functions of many plants and animals vary in [#permalink]

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18 Feb 2013, 04:32
plumber250 wrote:
If the passage was written like this (rough cut and paste)

72. Biological functions of many plants and animals
vary in cycles that are repeated every 24 hours. It is
temptingto suppose that alteration in the intensity
of incident light is the stimulus that controls
these daily biological rhythms.

But there is much evidence to contradict this hypothesis.

The relevant section ('in lines 2-5') is highlighted.

So if you look at it like that, then the official answer explanation makes perfect sense

I understand what they mean now, by saying "....than at night" they actually mean at night when the light was still incident on the algae. If they would have made the sentence parallel by saying "... during night hours" I may have gotten it.

This was a good one! Thanks for your help!
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Re: Biological functions of many plants and animals vary in [#permalink]

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20 Apr 2017, 13:07
Biological functions of many plants and animals
vary in cycles that are repeated every 24 hours. It is
tempting to suppose that alteration in the intensity
of incident light is the stimulus that controls
these daily biological rhythms. But there is much

Which of the following, if known, is evidence that contradicts the hypothesis stated in lines 2-5 above?

(A) Human body temperature varies throughout the day, with the maximum occurring in the late afternoon and the minimum in the morning.

- This option talks about the temperature impact on human body and nowhere mentions the impact of the light, hence this option is irrelevant.

(B) While some animals, such as the robin, are more active during the day, others, such as mice, show greater activity at night

- Once again, this option talk about day and night but we cannot conclude that light is playing a role in this behaviour. Hence, B is irrelevant too.

(C) When people move from one time zone to another, their biological rhythms adjust in a matter of days to the periods of sunlight and darkness in the new zone.
- Time zones is completely out of Scope.

(D) Certain single-cell plants display daily biological rhythms even when the part of the cell containing the nucleus is removed.
- Talks about biological rhythms but does not mention anything about light, once again out.

(E) Even when exposed to constant light intensity around the clock, some algae display rates of photosynthesis that are much greater during daylight hours than at night.

- This option is clearly taking into consideration the impact of light. It definitely weakens the argument.

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Re: Biological functions of many plants and animals vary in [#permalink]

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12 Nov 2017, 07:30
Read the second part of the question carefully, "alteration" in the intensity...reason for the change in biological rhythms.
so we are concerned with the change in light intensity, be it any light.

option E clearly states that, even after providing "constant light intensity" exposure to algae, rates of photosynthesis (biological rhythms)...greater during daylight hours( we are speaking only of hours, the light intensity is still constant) than at NIGHT( whoa!! there is a variation in biological rhythms!!...who the hell did it, definitely not light intensity coz that was kept constant throughout!)
whoa!! again hypothesis overruled

hope you understood it.

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Re: Biological functions of many plants and animals vary in   [#permalink] 12 Nov 2017, 07:30
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