Major organ systems of the plant body.

Structure of a leaf

Leaf structure (1) (2) (3) (4) (5) (6) Cross section of a leaf, showing the anatomical features important to the study of photosynthesis: stoma, guard cell, mesophyll cells, and vein.

Cross Section of A Leaf

Stomata Tiny pores found on the surfaces of a leaf Stomata take in carbon dioxide from the air through stomata Water vapour and oxygen passes out from the leaf to the atmosphere through stomata

Stomata and Guard cells

Let´s have a look at some stomata under the microscope! Prepare an epidermal impression by coating the leaf surface with nail varnish/clear sellotape. Peel off the dried layer of nail varnish/sellotape and stick this onto a slide. Draw what you see! -are the pores open or closed? why? -are there more pores on the top or bottom of the leaf?

Xylem vessels Are found in the roots and stems of plants, and in their leaves. They carry water and dissolved minerals from the roots of the plant, up through the roots and stem, and into the leaves and flowers. Their other function is to help to support the plant. Xylem vessels are made up of many long thin cells called elements. The elements are arranged end to end. They are very unusual cells, because they are dead! Their walls contain a very hard, strong substance called lignin. They have no cell surface membrane, no cytoplasm and no nucleus.

Phloem cells Function: Transport food (sugars) to where it is needed throughout the plant.