Why is it good for a leaf to be thin?
Its main functions are photosynthesis and gas exchange. A leaf is often flat, so it absorbs the most light, and thin, so that the sunlight can get to the chloroplasts in the cells. Most leaves have stomata, which open and close. They regulate carbon dioxide, oxygen, and water vapour exchange with the atmosphere.
The palisade cells are the main site of photosynthesis, as they have many more chloroplasts than spongy mesophylls, and also have several adaptions to maximise photosynthetic efficiency; Large Vacuole - Restricts chloroplasts to a layer near the outside of the cell where they can be reached by light more easily.
- The palisade cells are the main site of photosynthesis, as they have many more chloroplasts than spongy mesophylls, and also have several adaptions to maximise photosynthetic efficiency; Large Vacuole - Restricts chloroplasts to a layer near the outside of the cell where they can be reached by light more easily.
- In this section, we will discuss how a plant leaf is an example of an organ. We will present its structure with respect to its functions in photosynthesis, gaseous exchange and transport. Leaves are typically found in vascular plants, which have lignified tissues (xylem) that enable them to conduct water.
- Plants absorb water from the soil by osmosis. Root hair cells are adapted for this by having a large surface area to speed up osmosis. The absorbed water is transported through the roots to the rest of the plant where it's used for different purposes: It's a reactant used in photosynthesis.
Below the upper epidermis is the palisade layer. This is one or a few layers of cylindrical cells that contain many chloroplasts. Chloroplasts are an important part of plant cells because they are cell structures that allow for photosynthesis.
- They don't have organelles such as nuclei, mitochondria or chloroplasts. Although they do have ribosomes and a cell wall, these are both different in structure to the ribosomes and cell walls in the cells above. Bacteria cells do have a cytoplasm and cell membrane though.
- The Upper Epidermis of the leaf is transparent and lets light through to the Palisade Layer beneath. The Palisade Layer consists of long, thin Palisade Mesophyll Cells. They are specialised for carrying out Photosynthesis since they contain large amounts of Chlorophyll, and their long shape maximises light absorption.
- Palisade cells are found in the mesophyll of a leaf and their main function is the absorption of light so that photosynthesis can take place. The palisade mesophyll consists of chloroplasts with chlorophyll that absorb the light energy.
Updated: 2nd October 2019