Plant cell structure and celluloseEdexcel A-Level Biology A: Mind map

Exam questions on Plant cell structure and cellulose

1. A student examines two plant cells with an electron microscope: a palisade mesophyll cell from a leaf and a cell from a potato tuber. Both cells have a large central vacuole surrounded by a membrane.
   Describe two differences between a chloroplast in the leaf cell and an amyloplast in the tuber cell.2 marks
2. A virus infects a tobacco leaf and spreads through the leaf from cell to cell. Each plant cell is surrounded by a rigid wall, and neighbouring cells are held together by a layer between their walls. Microscopy shows thin channels crossing the walls between neighbouring cells, and thin areas of the wall called pits.
   Suggest how the virus could spread from cell to cell even though each cell is surrounded by a rigid cell wall.2 marks
3. Cotton fibres, which are used to make textiles, are almost pure cellulose. Potato tubers store large amounts of starch. Both cellulose and starch are polymers of glucose.
   Explain how the structure of starch makes it suitable as a storage molecule in the potato tuber.3 marks