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Questions
on transpiration pt 2
Monacia
Williams, Contributor
Welcome
to another lesson. I hope that you
all had a good week. Today, we will
continue with the question we started
last week. Yes, in case you are asking,
it was one question and it was not
completed last week! This week will
see it to its completion.
(v)
Describe the type of soil that would
be ideal for growing plants that require
a good supply of water. (2 marks)
Answer
Notice
that the examiners have introduced
a different topic here. This serves
as a reminder that you should not
pick topics for the examination; you
should try to study everything! What
would be the ideal soil? The ideal
type of soil is one that will hold
water without becoming waterlogged
and one that will provide nutrients
for the plant. This type of soil is
loam.
(b)
A similar experiment was conducted
to determine the effect of wind and
relative humidity on another plant.
Measurements of water absorbed were
taken after ever hour. The results
are shown in the following table:
TRANSPIRATION
RATE UNDER DIFFERENT CONDITIONS INDOORS
|
Hours
|
Water
Absorption Rate cm3/hr
|
|
Wind
15 Km hr-1
|
Relative
Humidity
90%
|
|
1
|
10
|
10
|
|
2
|
12
|
12
|
|
3
|
15
|
14
|
|
4
|
20
|
16
|
|
5
|
24
|
18
|
|
6
|
25
|
18
|
|
7
|
28
|
18
|
|
8
|
30
|
18
|
|
9
|
32
|
18
|
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(i)
Plot appropriate graphs on the grid
below to show the results of the experiment
shown in the table.
Answer
This
answer is testing your skills in drawing
graphs. Do you remember the lesson
we had together on this topic? If
you do not, then I suggest you go
back to it now and revise before you
attempt the question!
Remember
that the variable that the experimenter
is controlling goes on the X axis.
In this case, it would be hours since
the experimenter determines the intervals
at which the readings are made. The
other variable would now go on the
Y axis, since this is the dependent
variable. You also need to choose
suitable scales for both axes. Do
not forget the labels for the axes.
Since the two variables, wind and
relative humidity, will be plotted
on the same graph, you will need to
use two different symbols to represent
them and to write a key to indicate
which is which. If you acquire the
skills, this will be an easy four
marks to earn.
(ii)
The results in the first table were
collected from an experiment that
was conducted outdoors. Give one disadvantage
of conducting this experiment outdoors.
Answer
It
will be difficult to determine or
eliminate the influence of the different
factors on the rate of water absorption.
(iii)
Compare the effects of wind and relative
humidity as shown by the data in the
table. (2 marks)
Answer
The
rate of water absorption is the same,
10 and 12 cm3/hr, for both factors
for the first two hours, then the
rate begins to increase rapidly in
the wind speed, getting to a maximum
of 32 cm3/hr. In the 90 per cent relative
humidity, the rate increases slowly
to a maximum of 18 cm3/hr after which
there is no further increase for the
remaining hours of the experiment.
(iv)
Account for the response of the plant
to relative humidity as shown in the
table. (2 marks)
Answer
Ninety
per cent relative humidity indicates
that the air is almost fully saturated
with water vapour, therefore, there
would be no diffusion gradient created
and diffusion could not take place.
Since water is not being lost, only
the water being used by the plant
for its activities would need to be
replaced.
There
are many more questions on transpiration;
it is one of the popular topics for
the examinations, especially for Paper
02. These questions tend to be centred
on the transpiration experiments and,
therefore, require the use of mathematical
concepts. My advice to you is, start
practising how to answer these questions!
Have a good week!
Monacia
Williams teaches at Glenmuir High
School. Send questions and comments
to kerry-ann.hepburn@gleanerjm.com
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