Plant tissues

Organisation · Plant tissues, organs and systems · note 1 of 5

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Plant tissuesSpec 4.2.3.1

In short

Plant tissues are groups of cells whose structure suits their function. Epidermal tissues cover and protect the plant, palisade mesophyll has many chloroplasts for photosynthesis, and spongy mesophyll has air spaces for gases to diffuse. Xylem transports water and mineral ions, phloem transports dissolved sugars, and meristem tissue produces new cells for growth.

You need to be able to explain how the structures of plant tissues are related to their functions. Plant tissues include epidermal tissues, palisade mesophyll, spongy mesophyll, xylem and phloem, and meristem tissue.

Plant tissues
Tissue	Structure	Function
Epidermal tissues	A thin layer of cells covering the surface. In the leaf it is covered by a waxy layer	Protects the plant and reduces water loss. The leaf epidermis lets light through
Palisade mesophyll	Tall, tightly packed cells near the top of the leaf, containing many chloroplasts	Photosynthesis: absorbs light
Spongy mesophyll	Rounded cells with air spaces between them	Air spaces let gases such as carbon dioxide diffuse through the leaf. Photosynthesis also occurs here
Xylem	Hollow tubes strengthened by lignin	Transports water and mineral ions
Phloem	Tubes of elongated cells	Transports dissolved sugars
Meristem tissue	Found at the growing tips of shoots and roots. Cells divide and can become different types of cell	Produces new cells for growth

Exam tip:

Always give structure and function together: ‘many chloroplasts, so absorbs more light for photosynthesis’.

Written and checked against the AQA GCSE Combined Science (8464) specification · Updated October 2026

Frequently asked questions

How does water move from roots to leaves?

Water enters root hair cells by osmosis, then moves up through the xylem to the leaves in a continuous flow called the transpiration stream. In the leaf, water evaporates from the surface of the mesophyll cells into the air spaces, and water vapour diffuses out through the stomata. This loss of water vapour from the leaves is transpiration.

How does light intensity affect the rate of transpiration?

Increasing light intensity increases the rate of transpiration, because stomata open wider in the light, so more water vapour can diffuse out of the leaf. In darkness the rate falls. Higher temperature and more air movement also increase the rate of transpiration, while higher humidity decreases it. A potometer can be used to measure these effects.

What is the difference between xylem and phloem?

Xylem transports water and mineral ions from the roots to the stems and leaves in the transpiration stream, and is made of hollow tubes strengthened by lignin. Phloem transports dissolved sugars from the leaves to the rest of the plant by translocation, and is made of tubes of elongated cells with pores in the end walls.

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