Transport in Xylem
Transport in Phloem
Growth in Plants
Reproduction in Plants
Potometer Lab
100
A fungicide dissolved in water was applied to the soil in which a rose plant was growing. It later appeared in the leaves. How did the fungicide reach the leaves?
A. Movement up a water potential gradient
B. Transpiration pull in xylem
C. Translocation in phloem
D. Facilitated diffusion
B. Transpiration pull in xylem
100
In a plant, what tissue(s) is/are specially adapted to transport sucrose?
D
100
The image shows seedlings that have been exposed to unidirectional light. 
Which statement explains the growth towards the light source?
A. Light causes auxin to inhibit cell division in the shoot meristem.
B. Light causes auxin to promote cell division in the shoot meristem.
C. Auxin is concentrated in the side of the shoot with light and inhibits cell elongation.
D. Auxin is concentrated in the side of the shoot without light and promotes cell elongation.
D. Auxin is concentrated in the side of the shoot without light and promotes cell elongation.
100
Which process is matched with a valid example?
B
100
What is the function of the structure labelled X?
Water reservoir from which water can be let into the capillary tube, pushing teh air bubble back to the start of the tube
200
Cobalt chloride paper is blue when dry but turns pink with water. Blue cobalt chloride paper was fastened to the upper and lower surfaces of a plant leaf. After 20 minutes, many small pink dots were observed on the paper on the lower surface, and a few pink dots were seen on the upper surface. What conclusions can be drawn?
I. There are more stomata on the lower surface than on the upper surface.
II. Stomata on the upper surface are blocked by the waxy cuticle.
III. More transpiration occurs through the lower surface than through the upper surface.
I and III only
200
Which letter identifies phloem?
B
200
What is/are the effect(s) of auxin in plants?
I. Increasing the rate of cell elongation in stems
II. Changing the pattern of gene expression in shoot cells
III. Detecting the direction of light
A. I only
B. I and II only
C. II and III only
D. I, II and III
B. I and II only
200
Which flower structures are indicated by the letters Y and Z?
Y - Ovary (do not accept ovule or egg)
Z - Filament (do not accept stamen or anther)
200
Outline how the rate of water uptake is recorded in this potometer. [2]
a. measure distance «of movement» of air bubble/water in capillary tube
b. multiply by cross section of capillary
c. record/divide by time elapsed
Allow any other valid method.
300
Excessive irrigation can cause increased salinity in the soil. What effect does this have on water transport in the plant roots?
A. Decreases movement of water from soil into the root
B. Absorption of water with a higher solute concentration
C. Increases movement of water from soil into the root
D. Absorption of water with a lower solute concentration
A. Decreases movement of water from soil into the root
300
The diagram below shows part of the vascular system of a dicotyledonous plant. Which process is indicated by the arrows?
A. Passive translocation of sucrose from the sink to the source in the phloem
B. Active translocation of sucrose from the source to the sink in the phloem
C. Passive translocation of sucrose from the sink to the source in the xylem
D. Active translocation of sucrose from the source to the sink in the xylem
B. Active translocation of sucrose from the source to the sink in the phloem
300
A man attaches a bird box to the trunk of a dicotyledonous tree. A few years later he returns to the tree and finds that his bird box is still attached and the tree is much taller. How high will his bird box be from the ground?
A. Unchanged as growth from the apical meristem would be above the box.
B. Unchanged as growth from the lateral meristem would be above the box.
C. Higher as growth from the apical meristem would be below the box.
D. Higher as growth from the lateral meristem would be below the box.
A. Unchanged as growth from the apical meristem would be above the box.
300
Chrysanthemums are an important commercial flower. As a short-day plant, how can growers induce chrysanthemums to flower out of season?
A. Expose plants to short bursts of light for 24 hours
B. Expose plants to 15 hours of continuous light
C. Expose plants to 12 hours of light and 12 hours of darkness
D. Expose plants to 15 hours of continuous darkness
D. Expose plants to 15 hours of continuous darkness
300
State a variable that needs to be controlled in this experiment. [1]
temperature
OR
atmospheric pressure
OR
solar radiation/light
OR
wind speed
OR
leaf area
OR
size of plant
Do not accept humidity.
400
Under which conditions would the rate of transpiration be greatest?
A. Humid and cool with wind
B. Dry and hot with wind
C. Dry and hot with no wind
D. Humid and cool with no wind
B. Dry and hot with wind
400
Describe the distribution of vascular tissues in the stem of dicotyledonous plants. [2]
a. stem vascular tissue is in bundles ✔
b. «bundles» form a ring
c. phloem is towards outside «of bundle»
OR
xylem is towards centre «of bundle» ✔
Allow answers in an annotated drawing
400
What allows most plants to continue producing more roots, leaves or stems throughout their life?
A. Auxin
B. Meristems
C. Phloem
D. Cellulose
B. Meristems
400
What steps occur in germination after water uptake?
A. Gibberellin is produced, followed by amylase activation
B. Gibberellin stimulates photosynthesis to begin in the cotyledons
C. Amylase breaks down starch to glucose which activates the embryo
D. Amylase synthesis followed by activation of gibberellin
A. Gibberellin is produced, followed by amylase activation
400
Explain the effect of relative humidity on the rate of water uptake. [2]
a. increased «relative» humidity decreases water uptake
OR
inverse relationship
b. increased «relative» humidity lowers transpiration «rate»
c. diffusion gradient reduced «as humidity increases»
d. less loss of water through stomata
OR
stomata closed
Accept inverse for dry/low humidity.
500
In hot, dry conditions plants lose water rapidly due to transpiration. Explain how the structures and processes of the plant allow this water to be replaced. [8]
Evaporation of water «in leaf/mesophyll» creates tension/low pressure/negative pressure «potential»/pulling force/transpiration pull
Water drawn through cell walls/out of xylem «in leaf» by capillary action/adhesion «to cellulose»
Low pressure/tension/suction/pulling force in xylem
Hydrogen bonds make water cohesive/allow water to be pulled up under tension/allow the transpiration pull «to move water»
Xylem resists tension/low pressure/collapse with thickened/lignified walls
Water travels from the roots to the leaves in xylem
Water absorbed in roots by osmosis
Active transport of ions/solutes into roots «enabling osmosis»
Deep/wide ranging/extensive root systems/taproots/many root hairs
Thick/waxy cuticle reduces transpiration/water loss/evaporation
Small/no leaves/reduced surface area of leaves/thorns instead of leaves
Few stomata/stomata in pits/rolled leaves
Hairs on leaf surface «to reduce air flow near the leaf/reflect sunlight»
Stomata open at night/CAM physiology to reduce water loss
500
Explain how organic compounds are transported within plants. [7]
a. transported in/translocated in/loaded into phloem
b. in sieve tubes
c. by mass flow
d. from sources to sinks
e. from leaves/other example of source to roots/other example of sink
f. loading (of sugars/organic compounds) by active transport
g. cause high concentration of solutes (in phloem/sieve tubes)
h. water uptake (in phloem/sieve tubes) by osmosis/water diffuses into phloem
i. rise in (hydrostatic) pressure at source (in phloem)
j. creates a (hydrostatic) pressure gradient/higher pressure in source than sink
k. flow can be in either direction/bidirectional
500
Describe the roles of the shoot apex in the growth of plants. [5]
a. shoot apex is an «apical» meristem/has undifferentiated cells
b. mitosis «in shoot apex»
c. cell division/cytokinesis/cells produced «in shoot apex»
d. cell elongation «in shoot apex»
e. stem/shoot growth «due to the cell division and elongation in the shoot apex»
f. produces auxin
g. auxin stimulates growth/cell elongation
h. growth towards light
i. differentiation of cells «produced by the shoot apex»
j. leaf initiation/leaf development begins/leaf «primordia» formation «at shoot apex»
k. flowers produced «by shoot apex»
500
Explain how flowering is controlled in long-day and short-day plants. [7]
flowering affected by light;
phytochrome;
exists in two (interconvertible) forms/Pfr and Pr;
Pr (red absorbing/660 nm) converted to Pfr (far-red/730 nm absorbing) in red or day light;
sunlight contains more red than far red light so Pfr predominates during the day;
gradual reversion of Pfr to Pr occurs in darkness;
Pfr is active form / Pr is inactive form;
in long-day plants, flowering induced by dark periods shorter than a critical length / occurs when day is longer than a critical length;
enough Pfr remains in long-day plants at end of short nights to stimulate flowering;
Pfr acts as promoter of flowering in long-day plants;
short-day plants induced to flower by dark periods longer than a critical length/days shorter than a critical value;
at end of long nights enough Pfr has been converted to Pr to allow flowering to occur;
Pfr acts as inhibitor of flowering in short-day plants;
500
Transpiration in plants can be measured using a bubble potometer or a mass potometer.
Suggest a possible research question that could be investigated using a potometer. Then evaluate the limitations of using a potometer in the investigation you suggested. [5]
a. the research question identifies the independent variables
b. the research question identifies the dependent variable/derived value
c. the research question identifies the organism tested
If several variables are given, mark the first one only.
Examples:
a. Effect of changing/increasing wind/temperature/light/humidity/surface area/comparing different species
b. accept transpiration rate
c. accept common names.
--------------------------
a. not all of the water taken up by the plant is used for transpiration
b. some water taken up might be used for photosynthesis/ cell turgidity
c. (bubble) potometer measures rate of water uptake (not transpiration directly)
OR
bubble in potometer may expand due to changes in temperature/pressure
d. (cut) plant/twig gets damaged/may not survive
e. conditions in a lab are not equivalent to those in nature/ difficult to change only one abiotic factor
f. difficult to extrapolate values from a twig to whole plant