7 min readConcept sheet1-mark MCQ and assertion-reason; xylem vs phloem as a 2-mark question; water transport or translocation as a 3-mark question

Transportation in plants

Xylem carries water and minerals up from the roots, pulled mainly by transpiration. Phloem carries food made in the leaves to all parts: this is translocation.

XylemVessels and tracheids; water and minerals; upward only

PhloemSieve tubes and companion cells; food; up and down

TranspirationLoss of water as vapour from the aerial parts of a plant

TranslocationUses energy from ATP to load sucrose into phloem

Xylem vs phloem

XylemCarries water and minerals from the roots to the leaves. Made of vessels and tracheids, joined from root to leaf. Flow is upward only, driven by root pressure and transpiration pull.

PhloemCarries food (sucrose, amino acids and other substances) from the leaves to other parts. Made of sieve tubes with companion cells. Flow is up and down, using energy from ATP.

How water rises in xylem

1
Root cells in contact with the soil actively take up ions (minerals).
2
The ion concentration in the root becomes higher than in the soil, so water moves into the root from the soil.
3
Water keeps entering and pushes a column of water up the xylem: this is root pressure, most useful at night.
4★
In the day, water evaporates from the leaves through stomata (transpiration). This creates a suction that pulls water up from the roots.
5★
Transpiration pull is the main force that moves water up a tall tree during the day.

★ key step

How food moves in phloem (translocation)

1
Leaves make sugar by photosynthesis.
2
Sucrose is loaded into the sieve tubes using energy from ATP.
3
This raises the osmotic pressure in the phloem, so water moves into it.
4★
The pressure pushes the food towards parts with lower pressure: roots, fruits, seeds and growing buds.
In spring, sugar stored in roots or stems moves up to the buds

★ key step

Why transpiration is useful

It helps pull water and minerals up from the roots to the leaves.
It helps in temperature regulation: evaporation cools the leaves.
It removes extra water from the plant.

In real life

Transpiration keeps leaves cool, which is one reason the shade of a neem or banyan tree feels pleasant on a summer afternoon. Sugarcane tastes sweet because phloem carries sucrose from its leaves down into the stem.

Exam angle

2 marks: “Write two differences between xylem and phloem.” Xylem carries water and minerals upward; phloem carries food up and down. Xylem has vessels and tracheids; phloem has sieve tubes and companion cells.

3 marks: “How does water reach the leaves of a tall tree from its roots?” Root cells take up ions; water enters by the concentration difference and is pushed up as root pressure (mainly at night); transpiration from leaves creates suction (transpiration pull), the main force in the day.

2 marks: “What is translocation? Why does it need energy?” Movement of food such as sucrose in phloem. Energy from ATP is used to load sucrose into phloem, which builds the pressure that moves it.

Remember it

Xylem is a water lift that goes only up; phloem is a food delivery van that goes up and down.