Brainlag PlusThe tissues of a leaf, xylem and phloem, transpiration and the factors that change it, potometer calculations and stomatal density.
A leaf is an organ
- Epidermis with a waxy cuticle covers the leaf and cuts water loss.
- Palisade mesophyll: packed with chloroplasts, most photosynthesis.
- Spongy mesophyll: air spaces for gases to diffuse.
- Stomata, opened and closed by guard cells, let carbon dioxide in and water vapour out.
- Xylem: hollow tubes of dead cells strengthened with lignin; water and mineral ions go up from the roots.
- Phloem: columns of living cells with pores in the end walls; dissolved sugars go up or down (translocation).
- Meristem at shoot and root tips makes new cells.
The rest of this lesson and its 12 practice questions are in Plus.
Screen 1 of 4, free to read.
- 12 exam-style questions, marked as you go, each with a worked solution
- Anything you get wrong is saved to your flashcards