Question

1. Why use stains for microscopy? (1) 2. Use your knowledge of osmosis to explain the structural difference that you observed in the Elodea leaf after addition of the NaCI solution. (2) Which is larger: a eukaryotic cell or prokaryotic cell? Give an example of each. (3) 3. The vacuole of an onion epidermis cell takes up most of the cell. The cell of an Elodea leaf has no apparent vacuole. What would account for this difference? Think about where each plant is found and the function of that organelle. (1) 4.

Answer 1

Please find the answers below:

Answer 1: The living cells are colourless in nature and cannot be distinguished or observed properly under a microscope as they appear as opaque objects. Hence, permanent or temporary stains help in their visualisation.

Answer 2: NaCl solution makes a hypertonic solution and when any leaf is dipped into it, the movement of water takes place from the leaf into the solution. This makes the leaf shrink in size after some time.

Answer 3: An eukaryotic cell is indeed larger than a prokaryotic cell. For example, a bacterial cell ranges an average size of nearly 10 um whereas a neuron can be a meter long in length.

Answer 4: Vacuole generally function to trap air or other storage material in the leaves and this behaviour depends upon the habit and habitat of the plant. The observatory plant leaf must not require to store material, hence does not contain a vacuole.