O Level / IGCSE Biology chapter 7: Transport in flowering plants MCQs with answers
By Team Megalecture · Updated 4 Nov 2026
21 exam-style questions on Transport in flowering plants, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.
Ten Transport in flowering plants questions with answers
Try each one, then open the answer. These ten stay the same; the test draws new ones every time.
1. What is transpiration?
A
the uptake of water by roots
B
the loss of water vapour from leaves
C
the transport of sucrose in the phloem
D
the movement of water in the xylem only
Show answer
Answer: B. Transpiration is the loss of water vapour from the leaves, mainly through the stomata.
2. A lot of salt is added to the soil around a plant and the plant wilts. Why?
A
the roots absorb too much water by osmosis, so the leaves become too heavy
B
the soil solution has a lower water potential than the root cells, so water moves out
C
the salt is absorbed by the guard cells, which makes the stomata close and stops water uptake
D
the salt blocks the xylem vessels, so water cannot travel up the stem to the leaves
Show answer
Answer: B. Salt lowers the water potential of the soil water below that of the root cells, so water leaves the roots by osmosis instead of entering them. The cells become flaccid and the plant wilts.
3. Why does the rate of transpiration increase at a higher temperature?
A
the cuticle becomes thinner, so water passes straight through the leaf surface
B
the stomata close, so more water is forced out through the waxy cuticle instead
C
water molecules gain kinetic energy, so evaporation and diffusion are faster
D
the xylem vessels become wider, so water is pulled up the stem more quickly
Show answer
Answer: C. At higher temperatures water molecules have more kinetic energy, so they evaporate faster from the mesophyll cells and diffuse faster out of the leaf.
4. What is the effect of an increase in humidity on the rate of transpiration, and why?
A
it decreases, because the water vapour gradient between leaf and air is smaller
B
it increases, because there is more water vapour in the air for the leaf to absorb
C
it increases, because the stomata open wider when the air around the leaf is moist
D
it has no effect, because transpiration depends only on the number of open stomata
Show answer
Answer: A. In humid air there is less difference in water vapour concentration between the leaf air spaces and the air, so diffusion out through the stomata is slower and transpiration decreases.
5. Which feature helps root hair cells to absorb water?
A
a long, thin extension giving a large surface area
B
a thick waxy cuticle that prevents water loss
C
walls strengthened with lignin to carry water upwards
D
many chloroplasts to absorb light for photosynthesis
Show answer
Answer: A. Root hair cells have a long, thin extension that increases surface area for absorbing water and mineral ions. They have no chloroplasts, no cuticle and no lignin.
6. A leafy shoot with a total leaf area of 150 cm² loses 4.5 g of water in 3 hours. What is the rate of water loss, in g per cm² per hour?
A
0.09
B
1.5
C
0.03
D
0.01
Show answer
Answer: D. Mass lost per hour = 4.5 ÷ 3 = 1.5 g. Per cm² of leaf = 1.5 ÷ 150 = 0.01 g per cm² per hour. Dividing only by the area gives the loss over three hours, not per hour.
7. Why does water move from the soil into a root hair cell?
A
the cell contains more water than the soil does
B
the root hair cell uses energy from respiration to pump water in by active transport
C
the soil water has a lower water potential than the cell sap, so water is drawn in
D
the soil water has a higher water potential than the cell sap
Show answer
Answer: D. Water moves by osmosis from a higher to a lower water potential. The soil water has a higher water potential than the sap in the root hair cell, so water enters.
8. A stained cross-section of a dicotyledonous stem shows the dye in a ring of separate patches. Which statement about these patches is correct?
A
they are phloem tubes, which lie in a ring in the centre of the stem
B
they are pith cells, which store the dyed water in their vacuoles
C
they are vascular bundles, and the dye is in the xylem on the inner side of each one
D
they are cortex cells, which have taken up the dye by osmosis
Show answer
Answer: C. In a dicotyledonous stem the xylem and phloem lie together in vascular bundles arranged in a ring. Dye carried in the water is found in the xylem.
9. Why does wind increase the rate of transpiration?
A
it cools the leaf, so less water evaporates from the mesophyll cells
B
it removes water vapour from beside the leaf, so the gradient stays steep
C
it closes the stomata so that water vapour is trapped inside the leaf
D
it adds water vapour to the air around the leaf, so the leaf loses water faster
Show answer
Answer: B. Wind blows away the humid air next to the leaf, keeping the concentration gradient steep, so water vapour diffuses out faster and transpiration increases.
10. How does wilting occur?
A
more water is lost by transpiration than the roots can take up, so the cells become flaccid and lose their support
B
the stomata open too wide, which lets extra carbon dioxide in and damages the leaf
C
cells take in too much water, so they burst and the stem cannot support the leaves
D
the xylem vessels collapse because they lack lignin, so water cannot travel up
Show answer
Answer: A. If water is lost by transpiration faster than the roots can supply it, the cells lose water and become flaccid, so the plant wilts.
Transport in flowering plants: questions students ask
How many Transport in flowering plants MCQs are there?
21, each with the answer and a short explanation, across 2 topics: Uptake and transport of water and ions, Transpiration and translocation. Every chapter test draws ten of them, so you can take it many times.
Is the O Level / IGCSE Biology chapter 7 test free?
Yes. The test, the answers and the explanations are free and need no sign-up. Sign in only if you want your scores kept across devices.
How is the chapter test marked?
The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.
