Dendrochronology, the study of tree-ring records to glean

Question

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dendrochronology-the-study-of-tree-ring-records-to-glean-136138.html#p1106463

Dendrochronology, the study of tree-ring records to glean
information about the past, is possible because each year
a tree adds a new layer of wood between the existing
wood and the bark. In temperate and subpolar climates,
cells added at the growing season's start are large and
thin-walled, but later the new cells that develop are
smaller and thick-walled; the growing season is followed
by a period of dormancy. When a tree trunk is viewed in
cross section, a boundary line is normally visible between
the small-celled wood added at the end of the growing
season in the previous year and the large-celled spring
wood of the following year's growing season. The annual
growth pattern appears as a series of larger and larger
rings. In wet years rings are broad; during drought years
they are narrow, since the trees grow less. Often, ring
patterns of dead trees of different, but overlapping, ages
can be correlated to provide an extended index of past
climate conditions.

However, trees that grew in areas with a steady supply of
groundwater show little variation in ring width from year
to year; these "complacent" rings tell nothing about
changes in climate. And trees in extremely dry regions
may go a year or two without adding any rings, thereby
introducing uncertainties into the count. Certain species
sometimes add more than one ring in a single year, when
growth halts temporarily and then starts again.

The passage suggests which of the following about the ring patterns of two trees that grew in the same area and that were of different, but overlapping, ages?

A. The rings corresponding to the overlapping years would often exhibit similar patterns.
B. The rings corresponding to the years in which only one of the trees was alive would not reliably indicate the climate conditions of those years.
C. The rings corresponding to the overlapping years would exhibit similar patterns only if the trees were of the same species.
D. The rings corresponding to the overlapping years could not be complacent rings.
E. The rings corresponding to the overlapping years would provide a more reliable index of dry climate conditions than of wet conditions.

Friends, do you find the logic here, I think I lost somewhere! Thanks!

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abhijit_sen · Answer

Last line of first para says "Often, ring patterns of dead trees of different, but overlapping, ages can be correlated to provide an extended index of past climate conditions."

A. The rings corresponding to the overlapping years would often exhibit similar patterns.
This is not supported. Moreover in both trees have same pattern, it is then case of "complacent cells", it will not yield much of information.

B. The rings corresponding to the years in which only one of the trees was alive would not reliably indicate the climate conditions of those years.
Seems Correct. Because correlation is done exactly for this reason.

C. The rings corresponding to the overlapping years would exhibit similar patterns only if the trees were of the same species.
Not supported in passage.

D. The rings corresponding to the overlapping years could not be complacent rings.
May be may be not. Not supported in passage.

E. The rings corresponding to the overlapping years would provide a more reliable index of dry climate conditions than of wet conditions.
Nothing is passage supports that correlation will work better in dry conditions better than wet. In fact in dry trees will have unpredictable growth so thereby difficult to correlate and predict.

IMO B. Please post the OA.

Anon · Answer

A

The rings corresponding to the overlapping years would often exhibit similar patterns.

Last line of first para

rpmodi · Answer

I am bad at RC but I will try

E ?

"However, trees that grew in areas with a steady supply of 
groundwater show little variation in ring width from year 
to year; these "complacent" rings tell nothing about 
changes in climate."

So 
E :The rings corresponding to the overlapping years would provide a more reliable index of dry climate conditions than of wet conditions.

sondenso · Answer

Anon, can you say some more detail how you translate from "the last line of first para" to "exhibit similar patterns". So subtle, I think!

rpmodi · Answer

haha , I am way off !! god save me on 8th !

SV6 · Answer

IMO B
Keyword: different but Overlapping - ages (last sentence of first para)

Often, ring patterns of dead trees of different, but overlapping, ages can be correlated to provide an extended index of past climate conditions.

When we have "ring patterns of dead trees" (More than one) diffrent - we can correlate ages to predict the past climat condition.

But we have two trees here, one tree live and one tree dead , even though they have overlapping ages, it will not give us any information - which B says.

All other choices are not discussed in this.

alpha_plus_gamma · Answer

IMHO, C, D , E are clearly out.

I think A is the correct answer:

becuase " Often, ring patterns of dead trees of overlapping ages can be correlated to provide an extended index of past climate conditions ."
If the ring patterns of overlapping ages are often co-related to give info about past climate conditions, the rings should exhibit similar patterns, If the ring patterns for overlapping years would have been different, how would have it helped to co-relate past climate conditions.

Whats OA?

goalsnr · Answer

I got A by POE.

B .We donot have enough information to support the answer choice because its unkown if the trees compared are alive tress or dead trees.
C. Again the passage does not discuss anything about species. So no info to support this choice either.
D.Complacent rings - steady water suppy. The questions talks about trees grown in a particular area but does not give any info about the weather conditions or water supplied to the trees.
E. The questions talks about trees grown in a particular area but does not give any info about the weather conditions.

sondenso · Answer

Thanks guys, OA is A

But I still not get the point!

Dendrochronology, the study of tree-ring records to glean

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