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PHOTOSYNTHESIS (Internal adaptations (The mesophyll . (Palisade cell: …
PHOTOSYNTHESIS
Internal adaptations
Upper epidermal cells are coated by a waxy covering called the cuticle. This reduces evaporation and protects the leaf from damage and infections.
The upper epidermis consists of a single layer of transparent cells. These cells are transparent because they lack chloroplasts.
The mesophyll .
Palisade cell: Large, long cells packed vertically below the upper epidermis Maximum light absorption for photosynthesis
Spongy cell: Small, round cells with large air spaces in-between them Large surface area for gas exchange between cells and air spaces
Cells next to air spaces are covered by a thin film of water Gases from air spaces dissolve in water and then into cells
The lower epidermis forms a protective layer at the bottom of the leaf. It is punctured with small gaps in its surface called stomata.
External adaptations
The vein network is a branched transportation system. It transports water around the leaf and manufactured food to the rest of the plant. It also provides a scaffold that stretches the lamina out.
The lamina is the large flat surface of the leaf. It gives leaves a large surface area to trap light.
The petiole is the stalk that connects the leaf to the stem. It allows leaves to cover a larger area and minimises overlap between leaves.
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Plants produce their own food using light energy. This process is called photosynthesis.
6CO2 + 6H2O =====Light energy=====> c6H12O6 + 6O2
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Chlorophyll can best capture energy from blue or red light. and absorb very little green light.
it reflects almost all green light. This is why plants appear green.
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H2O enters the vacuole, cell wells and becomes turgid
H2O leaves the vacuole, cells shrink and becomes flaccid
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