2.5 The Unique STructures of Plant Cells

Question 1

The CELLULOSE CELL WALL

Answer 1

• made from the complex carbohydrate cellulose
• they are freely permeable
• gives plant cells their strong and rigid structure
• the contents of the cell push against the cell wall, creating a turgor which helps the cell to support its shape
• also acts as a defence mechanism against pathogens

Question 2

The PERMANENT VACUOLE

Answer 2

• membrane lined sacs containing cell sap
• very large so help to maintain the cells turgor bu pushing the cell’s contents against the cell wall
• the membrane of the vacuole is called the TONOPLAST, it is selectively permeable

Question 3

What are Chloroplasts?

Answer 3

• the organelles responsible for photosynthesis, and so are found in the stems and leaves but not the roots
• they have a similar structure to the mitochondria with the inner fluid known as the STROMA and the internal membranes form flattened membranous discs called THYLAKOIDS, which stack together to form GRANUM, which are joined together by lamellae
• the membranes of the thylakoids contain chlorophyll pigment which allows for light-dependent reactions to occur
• they contain their own DNA and are able to produce proteins