Reading Comprehension

Lina wrote: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.


PICK D

Plz have a look in to the colored portion..


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



The passage is primarily concerned with

(A) evaluating the effect of climate on the growth of
trees of different species
(B) questioning the validity of a method used to study
tree-ring records
(C) explaining how climatic conditions can be deduced
from tree-ring patterns

Pick C
(D) outlining the relation between tree size and cell
structure within the tree
(E) tracing the development of a scientific method of
analyzing tree-ring patterns

Please explain your answers

Testluv wrote:received a pm.

The passage was fairly straightforward but there are some very tempting wrong answers in these two questions.

Question 1:

The correct answer must be choice A.

If we have two trees that are from the same area, then of course the climate would have been the same in any given year. (It would be bizarre if we had significantly different climates at the same time in the same place).

So, for two trees from the same area, the rings corresponding to overlapping years would, according to the passage, undoubtedly exhibit similar patterns.

For choice B, note that the passage never asserts that legions of trees are necessary to arrive at conclusions about past climatic conditions. If we have only one tree, of course it is less convincing than if we have many (as always, a larger sample size provides a more solid foundation for arriving at confident conclusions). However, based on the explanation in the passage, there is no reason to think that an expert would require multiple trees to read off past climate conditions; the method described did not in any way depend on some sort of comparison of tree rings in multiple trees.

(Govi, choice D is wrong--the rings may be complacent if the two trees are in an area with a lot of groundwater).

Question 2:

The correct answer must be choice C.

For the bulk of the passage, the author is explaining how past climatic conditions can be deduced using tree ring patterns. Yes, he points to some limitations in the breadth of the method in paragraph 2. That just means that the method isn't 100% perfect or 100% applicable all of the time (what procedure is?).

But just because he is narrowing the scope of the method (ie, excluding certain groups of trees from reliable application of the method) certainly doesn't mean that he thinks the method itself is invalid. Thus, choice B is incorrect.

Testluv wrote: Question 1:

The correct answer must be choice A.

If we have two trees that are from the same area, then of course the climate would have been the same in any given year. (It would be bizarre if we had significantly different climates at the same time in the same place).

So, for two trees from the same area, the rings corresponding to overlapping years would, according to the passage, undoubtedly exhibit similar patterns.

Testluv wrote:received a pm.

The passage was fairly straightforward but there are some very tempting wrong answers in these two questions.

But just because he is narrowing the scope of the method (ie, excluding certain groups of trees from reliable application of the method) certainly doesn't mean that he thinks the method itself is invalid[/i]. Thus, choice B is incorrect.