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Specialised plant cells are plant cells with structures adapted for a specific role, such as root hair cells, xylem cells and phloem cells. Free notes.
Specialised Cells in Plants is part of Cell structure in GCSE Edexcel Higher Biology.
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GCSE Edexcel Higher
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Specialised plant cells are plant cells with structures adapted for a specific role, such as root hair cells, xylem cells and phloem cells. Free notes.
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Use this lesson to stay inside Cell structure while connecting the detail back to the wider Topic 1: Key concepts in biology topic.
Read the core explanations from Specialised Cells in Plants before testing yourself from memory.
A plant faces a massive challenge: it needs to move water from its roots buried in soil up to leaves that might be 30 metres high. At the same time, it must transport the sugar it makes in its leaves down to every growing part. No single cell type could handle both jobs efficiently.
This is where cell specialisation becomes crucial. Just like workers in a factory have different jobs, plant cells develop specific structures and functions. Some become expert absorbers, others become transport tubes, and others become sugar highways.
Picture the root of a plant under a microscope. You'll see thousands of tiny projections sticking out like microscopic fingers. These are root hair cells, and they're perfectly designed for one job: maximum absorption.
The key adaptation is that long, thin projection - the root hair itself. This single extension can increase the cell's surface area by up to 10 times. More surface area means more space for water molecules to enter the cell through osmosis.
Trap: Many students think root hairs are separate structures. Actually, each root hair is just an extension of a single cell - like stretching out your finger to reach something.
Once water enters the root hair cells, it needs to travel upward - sometimes dozens of metres. This is where xylem comes in. Think of xylem as a plant's plumbing system, but with a twist: the pipes are made of dead cells.
Here's what makes xylem cells so effective: they die and lose their cell contents, creating hollow tubes. Their cell walls are strengthened with a tough substance called lignin, preventing the tubes from collapsing under pressure. The end walls between cells break down, creating one continuous pipeline.
Water moves up through xylem by transpiration - as water evaporates from leaves, it pulls more water up from the roots like sucking through a straw.
While xylem handles water transport, phloem has a different job: moving the sugar (glucose) that leaves make during photosynthesis to everywhere it's needed. Unlike xylem, phloem cells stay alive to actively control this transport.
Phloem contains two main cell types working as a team. Sieve tube elements are the transport tubes - they're living cells but have lost most of their internal structures to make space for sugar solution. Companion cells sit alongside them, keeping the sieve tubes alive and controlling what moves through them.
The key difference from xylem: phloem transport is active and can go in any direction. Sugar might flow down to growing roots in spring, or up to developing fruits in summer.
Now you can see how these three cell types work together like a well-organised delivery system. Root hair cells are the loading dock, xylem is the water delivery service, and phloem is the food distribution network.
Worked example: Tracing Water and Sugar Movement
Describe the journey of water from soil to leaf, and sugar from leaf to root
Answer: Water: soil → root hairs → xylem → leaves. Sugar: leaves → phloem → roots and growing parts.
Specialised cell questions follow predictable patterns. Examiners love to test whether you can link structure to function - explaining exactly how each adaptation helps the cell do its job better.
Common exam mistakes include confusing what each tissue transports (xylem carries water, phloem carries sugars) and forgetting that xylem cells are dead while phloem cells are alive. Practice explaining why each structural feature helps the cell's function.
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Move to the related lessons or back to the topic page when you need the wider sequence before exam-style practice.
Specialised plant cells are plant cells with structures adapted for a specific role, such as root hair cells, xylem cells and phloem cells. Root hair cells absorb water and mineral ions, xylem transports water up from the roots, and phloem transports sugars around the plant.
Lignin is a tough substance that strengthens the cell walls of xylem cells. It prevents the xylem tubes from collapsing under pressure as water and mineral ions are transported from the roots to the leaves.
Root hair cells are specialised by having a long, thin projection that can increase the cell's surface area by up to 10 times. More surface area means more space for water to enter by osmosis and for mineral ions to be absorbed from the soil.
Xylem cells are dead because they die and lose their cell contents, creating hollow tubes for water to flow through. The end walls between cells break down, forming one continuous pipeline from the roots to the leaves.
Companion cells sit alongside sieve tube elements in the phloem, keeping the sieve tubes alive and controlling what moves through them. Together the two cell types transport dissolved sugars around the plant.
Water enters root hair cells from the soil by osmosis, then moves up through the xylem tubes to the leaves. As water evaporates from leaf surfaces in transpiration, it pulls more water up from the roots like sucking through a straw.
Sieve tube elements are the transport tubes of the phloem. They are living cells that have lost most of their internal structures to make space for the sugar solution moving through them.
A root hair cell is adapted for absorbing water and mineral ions from soil by having a long, thin projection that dramatically increases its surface area. This root hair can increase the cell's surface area by up to 10 times, giving more space for water to enter by osmosis.
Xylem cells are dead, hollow cells arranged end-to-end to form continuous tubes that transport water and mineral ions from roots to leaves. Their cell walls are strengthened with lignin to stop the tubes collapsing, and the end walls between cells break down to form one continuous pipeline.
Phloem is living tissue that transports dissolved sugars, mainly sucrose, from leaves to all parts of the plant. Sieve tube elements have lost most of their internal structures to make space for sugar solution, while companion cells keep the sieve tubes alive and control what moves through them.
Phloem transport can go in any direction, unlike xylem. Sugar might flow down to growing roots in spring or up to developing fruits in summer, because living phloem cells actively control the transport.
A root hair is not a separate structure: each root hair is just an extension of a single root hair cell. It works like stretching out a finger, increasing the surface area for absorbing water and mineral ions.
Sugar moves around a plant through the phloem. Leaves make glucose during photosynthesis, the glucose is converted to sucrose for transport, and the sucrose moves through phloem to the roots and other growing parts.