Plant cell structureEdexcel International A Level Biology: Mind map

Exam questions on Plant cell structure

1. A student examines an electron micrograph of a palisade mesophyll cell from a leaf. The cell has a thick layer outside its plasma membrane, a very large sac occupying most of the cell interior, and several oval organelles containing stacks of flattened membranes.
   The cell is placed in distilled water. Explain why it does not burst.2 marks
2. A potato tuber stores energy over the winter. Cells from inside a tuber were stained with iodine solution and viewed under a light microscope. Many organelles in the cells contained dark blue-black granules.
   Explain why the tuber stores energy as starch in amyloplasts rather than as glucose in the cytoplasm.2 marks
3. A researcher injects a fluorescent dye into one parenchyma cell in the stem of a plant. Within minutes the dye is detected in the neighbouring cells, even though the dye cannot cross the plasma membrane. Microscopy shows that where the dye passes between the cells, the cell wall is thin.
   Explain how the dye could move from the injected cell into its neighbours.3 marks