Transport in plants
1 All of the
following statements are true but which one is the most precise?
Water is conducted through plant stems in
(a) the xylem, (b) vascular bundles, (c) vessels, (d) veins.
2 Which of
the following statements is the most accurate?
(a) Food can travel up the stem in the phloem.
(b) Food can travel down the stem in the phloem.
(c) Food can travel up or down the stem in the phloem.
(d) Food can travel up or down the stem in the xylem.
3 Roots have
no chlorophyll and grow in darkness. So how do roots obtain their food?
4 Which of
the following conditions is least likely to increase the rate of transpiration
in a
plant?
(a) a rise in temperature
(c) increased air movement
(b) an increase in humidity
(d) increased sunlight
5 Which of
the following statements are true of transpiration
(a) it draws water up the stem
(b) it draws dissolved salts up the stem
(c) it draws food up the stem
(d) it has a cooling effect on the leaves
(e) it speeds up photosynthesis?
6 Osmosis
and transpiration both play a part in the movement of water through a plant.
Which of these two processes makes the
greater contribution to the movement of water up
the trunk of a tree?
7 Which of
the following statements are true?
A potometer is an apparatus which can be
used to:
(a) measure the rate of water uptake in a shoot
(b) measure the rate of transpiration in a shoot
(c) measure the rate of photosynthesis in a shoot
(d)
compare rates of transpiration in different conditions
8 Most of
the water taken up by a plant passes through it and is evaporated to the
atmosphere. What use is made of the tiny fraction of this water which is
retained by the plant?
9 A student
set up a potometer in the laboratory and measured the rate of movement of water
in the capillary. An average of four readings gave a rate of 50mm per minute.
The apparatus was then taken outside, where there was a light breeze. Four more
readings were taken without delay. The average of these readings was 130 mm per
minute.
The student concluded that exposure of the
shoot to rapid air movement had increased the rate of transpiration.
Criticise the design of the experiment and
the student's conclusions.
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Transport in plants - continued
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a
potometer.
Criticise the design and practicability of
the apparatus.
11 A pot
plant was watered and the pot
enclosed in a plastic bag tied securely
round the base of the stem. The plant was
weighed at 9 a.m. and 4 p.m. During this
time it lost 32g in weight.
(a) From these results, what was the plant's
rate of transpiration?
(b)
Why might this calculated rate be slightly
inaccurate (i) in daylight, (ii) in darkness?
(c)
What was the point of (i) watering the
plant, (ii) enclosing the pot in a plastic bag?
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It is necessary
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