EDEXCEL UNIT

2 PLANT STRUCTURE  AND FUNCTION 

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Cell wall

• Rigid structure surrounding plant cells;

• Cellulose;

• Supports plant cells

 

Middle lamella

• Outermost layer;

• Adhesive;

• Stability

 

Plasmodesmata

• Channels in cell wall that link adjacent cells together

• Transport of substances and communication between cells

 

Pits

• In very thin regions;

• Arranged in pairs;

• Transport of substances between cells

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Chloroplast

• Small and flattened;

• Surrounded by double membrane;

• Thylakoid membranes;

• Stacked to form grana;

• Grana linked by thin, flat lamellae;

• Photosynthesis

(Some in grana; some in stroma – thick fluid in the chloroplast)

 

Amyloplast

• Small organelle enclosed by membrane;

• Starch granules;

• Storage of starch;

• Converts starch back to glucose;

 

Vacuole & Tonoplast

• Vacuole is a compartment surrounded by a membrane called the tonoplast

• Vacuole contains cell sap (water, enzymes, minerals, waste products)

• Turgidity to prevent wilting

• Breakdown and isolation of unwanted chemicals

• Tonoplast controls what enters and leaves the cell