Additional Science - OCR gateway - Biology - Module 4

Contents:
Plant Leaves 

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  • Created by: Sadia :)
  • Created on: 19-03-12 20:08

Plant Leaves

PHOTOSYNTHESIS:
Occurs in the leaves of plants.

LEAVES ARE ADDAPTED FOR EFFICIENCY:
Contains chlorophyll (which absorbs light) in millions of chloroplasts.
Is broad and flat to provide a huge surface area to absorb sunlight.
Is thin so that the gases (Carbon dioxide & Oxygen) only have a short distance to travel to and from the cells.
Has stomata on the underside of the leaf to prevent waterloss.  

DURING PHOTOSYNTHESIS:
Carbon dioxide difuses in through the stomata.
Oxygen difuses out through the stomata.
Water is absorbed through the roots.

IN A TYPICAL LEAF:
Upper Epidermis --> Transparent --> To allow sunlight through to the layer below
Palisade Cells --> At the top of the leaf --> Are packed with chloroplasts so they can absorb the maximum amount of light  
Spongy Mesophyll --> Contains Air Spaces --> To allow the optimum exchange of gases 

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Comments

Sarah

Helpfull for B4a, thankyou

Luisa Capocci

quite hard to understand but still quite good 

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