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2024 AQA A LEVEL BIOLOGY MASS TRANSPORT IN PLANTS YEAR 1 EXAM WITH CORRECT ANSWERS
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2024 AQA A LEVEL BIOLOGY MASS TRANSPORT IN PLANTS YEAR 1 EXAM WITH CORRECT ANSWERS
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2024 AQA A LEVEL BIOLOGY MASSTRANSPORT IN PLANTS YEAR 1
EXAM WITH CORRECT ANSWERS
What is the name of the theory for how water moves through a plant? -
CORRECT-ANSWERSCohesion-tension theory
From which cells in the leaf does water evaporate? - CORRECT-
ANSWERSSpongy mesophyll cells
Why is water pulled up as a column in the xylem? - CORRECT-
ANSWERSThere are cohesive forces between water molecules (hydrogen
bonding)
How does the cohesion-tension theory describe water moving through a
plant? - CORRECT-ANSWERS1. Water evaporates/transpires from the leaf
2. Water potential at stomata decreases
3. Water is drawn out of the xylem to replace the water lost
4. This creates tension
5. Water is pulled up as a column
6. Water enters the stem from the roots
Why is it important that the xylem vessels are narrow tubes? - CORRECT-
ANSWERSIncreases the surface area for adhesion of water to the walls of the
xylem
What is the purpose of the pores in the walls of the xylem? - CORRECT-
ANSWERSTo allow water to move in and out of the xylem
True or False
Lignin in the cells walls of xylem vessels means the cells are waterproof -
CORRECT-ANSWERSTrue
Why is water usually lost from the leaf? - CORRECT-ANSWERSThere is a lower
water potential outside the leaf than inside
Water diffuses down the water potential gradient out of the leaf
How is water usually lost from a leaf? - CORRECT-ANSWERSThrough the
stomata
, Complete the sentence
Water and mineral ions move from to - CORRECT-ANSWERSFrom roots to
leaves
Why does a potometer not measure the rate of transpiration? - CORRECT-
ANSWERSWater used in photosynthesis
Water produced in respiration
Water used for turgidity
True or False
A potometer measures the rate of transpiration - CORRECT-ANSWERSFalse
Measures rate of water uptake
How does water enter a plant cell? - CORRECT-ANSWERSIt moves down a
water potential gradient across the partially permeable membrane
By osmosis
What is an advantage of transpiration? - CORRECT-ANSWERSThe constant
stream of water also transports ions around the plant
The evaporation has a cooling effect, stopping the enzymes being denatured
if the plant overheats
Why is there cohesion between water molecules? - CORRECT-ANSWERSThey
are polar molecules
Hydrogen bonding
How are organic substances moved through a plant? - CORRECT-ANSWERSBy
translocation
In the phloem
Describe the phloem - CORRECT-ANSWERSElongated cells joined end to end
Holes in end walls - sieve plates
In bundles in the steam
Very few organelles/cytoplasm
Why is there a higher rate of respiration when there is a high concentration
of sucrose at the source? - CORRECT-ANSWERSSucrose --> glucose
Glucose can be respired
Why do phloem cells need companion cells? - CORRECT-ANSWERSThey have
lost many of their organelles e.g nucleus when they are specialised
It helps them repair and maintain themselves
Produces ATP for active transport of H+
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