2.2 Structure of the Angiosperm leaf Flashcards
Name the 7 main parts of the leaf from top to bottom
- Waxy cuticle
- upper epidermis
- palisade mesophyll
- spongy mesophyll (with air spaces)
- vascular bundles (xylem and phloem)
- Guard cells
- Stomata
What are the adaptations of the leaf for harvesting light energy?
- Transparent cuticle
- Thin so light penetrates easily
- palisade packed with chloroplasts which orientate themselves towards the light
- Chloroplasts filled with photosynthetic pigments to absorb light
What are the adaptations of the leaf for inward diffusion of carbon dioxide?
-Stomata on underside of leaf open to allow gas exchange
-Thin for short diffusion pathway
-Spongy mesophyll contains air spaces for diffusion of gases
-Mesophyll cells in contact with air in air spaces provides very large surface area
-Mesophyll cell surface covered in water for dissolving gas before diffusion
How are products of photosynthesis transported from the leaves to other areas of the plant?
Glucose is converted to sucrose for transport in the phloem
What is the role of the stomata?
Stomata open to allow gas exchange
Stomata close to limit water loss through evaporation
What is the role of the waxy cuticle?
Reducers water loss via evaporation
What is the role of the upper epidermis?
Transparent(allow light to pass for photosynthesis).
Synthesises to secrete waxy cuticle
What is the role of the palisade mesophyll?
main photosynthetic tissue
contains many chloroplasts
What is the role of the spongy mesophyll + air spaces ?
-also carry out photosynthesis due to chloroplasts
-air spaces allow for circulation of gases
What is the role of the vascular bundles?
xylem = water + mineral transport
phloem = transport of sucrose + amino acids
What is the role of the guard cells?
become turgid and flaccid due to changes in water potential. This opens and closes the stomatal pore.
