Photosynthesis Essay Example
Photosynthesis
The leaves are the part of a plant where most photosynthesis takes place. If you cut a leaf in half and look at the cut end, it would look like this:
Key:
1. Waxy cuticle: this gives the leaf a waterproof layer, which lets in light. 2. Upper epidermis: provides an upper surface.
3. Palisade cells: contain chloroplasts.
4. Spongy mesophyll: collection of damp, loosely packed cells.
5. Lower epidermis: layer of cells on the lower surface.
6. Air space inside the leaf: allows contact between air and moist cell surfaces.
7. Stoma: a hole in the leaf through which gases diffuse.
8. Guard cells: change shape to close the stoma.
One unique feature of leaves is that they have tiny holes in them to let carbon dioxide and oxygen enter and exit. The hole formed between these cells is called a stoma. A stoma is just a hole. It is controlled by two guard cells, which change shape to either open or close the hole. Something makes water enter the cells by osmosis and so they swell up and change shape, but no one is quite sure of the trigger. The stomata (air holes) on plants are normally open during the day and closed at night. These stomata are found on the undersides of leaves. This is because if they faced the sunlight, some of the plant's precious water could evaporate out of them.
[IMAGE] Guard cells
Hole
Open stoma Closed stoma
Photosynthesis is the way that plants make their food using energy from sunlight. This is the word equation:
[IMAGE]
Plants use the green dye (or pigment) called chlorophyll to pick up the energy from the sunlight. Plants make sugar and use some of it for energy to keep them alive (respiration) but they also use some for growth and repair by making fats and proteins. However, it is not always sunny so plants need to be able to store some of the sugar they make, so they convert it to a storage carbohydrate (starch). Plants
The leaves are the part of a plant where most photosynthesis takes place. If you cut a leaf in half and look at the cut end, it would look like this:
Key:
1. Waxy cuticle: this gives the leaf a waterproof layer, which lets in light. 2. Upper epidermis: provides an upper surface.
3. Palisade cells: contain chloroplasts.
4. Spongy mesophyll: collection of damp, loosely packed cells.
5. Lower epidermis: layer of cells on the lower surface.
6. Air space inside the leaf: allows contact between air and moist cell surfaces.
7. Stoma: a hole in the leaf through which gases diffuse.
8. Guard cells: change shape to close the stoma.
One unique feature of leaves is that they have tiny holes in them to let carbon dioxide and oxygen enter and exit. The hole formed between these cells is called a stoma. A stoma is just a hole. It is controlled by two guard cells, which change shape to either open or close the hole. Something makes water enter the cells by osmosis and so they swell up and change shape, but no one is quite sure of the trigger. The stomata (air holes) on plants are normally open during the day and closed at night. These stomata are found on the undersides of leaves. This is because if they faced the sunlight, some of the plant's precious water could evaporate out of them.
[IMAGE] Guard cells
Hole
Open stoma Closed stoma
Photosynthesis is the way that plants make their food using energy from sunlight. This is the word equation:
[IMAGE]
Plants use the green dye (or pigment) called chlorophyll to pick up the energy from the sunlight. Plants make sugar and use some of it for energy to keep them alive (respiration) but they also use some for growth and repair by making fats and proteins. However, it is not always sunny so plants need to be able to store some of the sugar they make, so they convert it to a storage carbohydrate (starch). Plants