New GCSE Science Revision and Learning
Biology - plant tissues and xylem - key facts to remember
For the plant tissues, organs and systems topic the first thing you’ll need to learn about is plant tissues and xylem. We’re going to cover everything you need to know about them for the new GCSE Biology syllabus.
Let’s start by going through each of the definitions of the tissues that make up a plant
Plant tissues
The palisade mesophyll is where light absorption happens. The cells are organised closely to one another to absorb as much light energy as possible. This plant tissue contains lots of chloroplasts. The palisade cells are column shaped.
The spongy mesophyll is where gas exchange happens. All the spongy mesophyll cells are loosely organised in contrast to the palisade mesophyll. The cells are covered over by a very thin layer of water. For the spongy mesophyll to be able to enter inside the leaf, gases must diffuse. These gases diffuse through stomata which are small pores on the leaf’s surface.
Epidermal tissues can also be found in plants.
Xylem
Xylem transports all the mineral salts and water around the plant. These will be moved from the roots at the bottom of the plant to other parts all of the plant.
Mature xylem are arranged end to end and form tubes or vessels. Mature xylem is made up of extended dead cells. They’re impermeable to water and contain no cytoplasm. Mature xylem also have strong walls which contain lignin which is a woody material.
To learn more about plant tissues and discover what other tissues there are, check out our other songs on Phloem and more! Why not check out our plant tissues song too if you haven’t! It goes through all the key points on this factsheet.
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