Specialised Plant Cells

The three main structures found in plant cells are:

  • Chloroplasts
  • Permanent vacuole
  • Cellulose cell wall

Root hair cells

Roots are covered with hairs, which increase the surface area of the root. Root hair cells are long thin hairs found inside the roots of plants. They increase the surface area for the absorption of water and mineral ions into the plant.

Root hair cells have many adaptations:

  • The cell has root hairs, which increases the area of the root.
  • A thin cell wall allows water to pass through easily, as it provides a shorter diffusion distance.
  • Unlike other plant cells, root hair cells do not contain any chloroplasts – Photosynthesis requires light energy from the Sun. As roots are underground, they do not need chloroplasts.
  • They contain mitochondria for the active transport of mineral ions.
  • Their permanent vacuole increases the rate of osmosis.
Illustrative diagram showcasing the absorption of water and minerals from soil by plant roots. The detailed section depicts the cellular structure of a root hair, highlighting features like the cell wall, cytoplasm, vacuole, and nucleus. Surrounding the root hair are soil particles from which water and minerals are being absorbed into the root hair. To the right, the process is summarised showing water and minerals moving from the soil, through the roots, and eventually being utilised by the whole plant, represented by a small small green plant. Arrows indicate the direction of nutrient flow. The background is white.

Guard cells

Guard cells are found in plant cells and they control the opening and closing of the stomata on the surface of the leaf. The function of a guard cell is to allow gas exchange and control water loss within the leaf

A comparative diagram depicting two states of a stoma on a plant's leaf: closed and open. On the left, the 'Stoma closed' illustration shows two tightly packed guard cells with labelled structures such as the nucleus, chloroplasts, vacuole, cell wall and the guard cell itself. On the right, the 'Stoma open' illustration displays the same labelled structures, but with the guard cells curved away from each other, creating an opening called the stoma. The background is white.

The guard cells become rigid or flaccid, changing shape depending on the condition of the plant.

Xylem cells

Xylem cells are found in the plant stem. Collectively, they form long tubes that are responsible for the transportation of water and dissolved mineral ions, from the roots to the leaves. Substances in the xylem are transported by transpiration.

There are many adaptations in xylem cells, such as:

  • No end top and bottom walls, which forms a long tube. This allows the water and dissolved minerals to be drawn upwards by transpiration.
  • The cells have very thick walls, which are lined with a chemical called lignin. This chemical provides a waterproof barrier and it strengthens the tube, which helps to support the plant.
  • Xylem cells have no internal structures such as a nucleus, a vacuole, cytoplasm or chloroplasts. This makes it easier for water and mineral ions to pass through.
Illustration of a xylem vessel, a tall green cylindrical structure. Blue arrows within the vessel indicate the upwards movement of water and minerals, labelled as "one-way only." The vessel is annotated to highlight the absence of end walls between cells, described as "No end walls between cells." The image is set against a white background.

Phloem cells

Phloem cells are responsible for the transportation of dissolved sugars and amino acids up and down the plant. They are also found in the stem.

Substances in the phloem are transported by translocation, which is an active process. The phloem is made up of two different types of cells:

  • Vessel cells – These cells have no nucleus, and each one is joined end-to-end. The end walls of the vessel cells have sieve plates, which allow the dissolved substances to flow through.
  • Companion cells – Each vessel cell is connected to a companion cell. Since transporting substances in the phloem requires energy, the companion cell provides this energy to the vessel cell.
Illustration of a phloem vessel, depicted as a series of connected green cells. Orange arrows within the vessel show a "two-way flow" of water and food. The image highlights the presence of end walls in the cells, labelled as "Cells have end walls with perforations." The image has a white background and is topped with the title "Phloem vessel."

You’ve used 10 of your 10 free revision notes for the month

Sign up to get unlimited access to revision notes, quizzes, audio lessons and more

Sign up