Ultrastructure Of Plant Cells

Question 1

Structure and function of the cell wall

Answer 1

• cell wall made of cellulose a complex carbohydrate
• freely permeable do substances move into and out of it
• cell wall gives the plant shape, the contents of the cell push against the cell wall making it rigid
• cell wall is a defence mechanism protecting the contents of the cell against pathogens

Question 2

Structure and function of the vacuole

Answer 2

• vacuoles are membrane lined sacs in the cytoplasm
• they contain cell sap
• vacuoles aid the maintenance of turgor, so the contents of the cell push against the cell wall
• membrane is called tonoplast and is selectively permeable
• animal vacuoles are small and not permanent

Question 3

Structure and function of the chloroplast

Answer 3

• chloroplast are responsible for photosynthesis
• they have a double membrane structure similar to mitochondria
• fluid enclosed in the chloroplast is called stroma
• internal membrane form flattened sacs called thylakoids, thylakoids stacked are grana
• lamellae join grana, grana contain the chlorophyll where light dependant reactions occur