3.3 Movement of Substances Across a Plasma Membrane in Living Organisms 12 May 2022 1 I. ACTIVE AND PASSIVE TRANSPORT IN ROOT HAIR CELLS Diagram 1 Essay: Explain the differences in the intake of water molecules and nitrate ions by plant root hair cells. [6 Marks] ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………….. ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………….. ………………………………………………………………………………………………… ………………………………………………………………………………………………….. 1)Water diffuses from soil water into the root hair cells by osmosis. 2)Mineral ion absorbed into the root hair cell through active transport.
3.3 Movement of Substances Across a Plasma Membrane in Living Organisms 12 May 2022 2 II. EFFECT OF ISOTONIC, HYPOTONIC AND HYPERTONIC SOLUTION ON ANIMAL CELLS 0.50M NaCl solution _______________________ 0.15M NaCl solution _______________________ Distilled water ________________________ ▪ 0.50M sodium chloride solution is hypertonic to the red blood cells ▪ 0.15M NaCl solution is isotonic to the cytoplasmic fluid of red blood cells. ▪ Distilled water is hypotonic to the red blood cells ▪ Water diffuses out of cell by osmosis ▪ No net movement of water across the plasma membrane ▪ Water diffuses into and out of the cell by osmosis at the same rate ▪ Water diffuses into the cell by osmosis ▪ Cell crenated// Crenation occurs ▪ - ▪ Cell haemolysed // Haemolysis occurs ▪ Cell decreases in size ▪ Red blood cells maintain their normal shape ▪ Cell increases in size // enlarged / expands ▪ Cell shrinks/ crinkle up / shrivel ▪ Normal shape and size ▪ Cell swells and bursts / ruptures 1. Diagram 2.1 shows the shape of red blood cells after being immersed for 30 minutes in three solutions with different concentration. Diagram 2.1
3.3 Movement of Substances Across a Plasma Membrane in Living Organisms 12 May 2022 3 (a) State the condition of the red blood cells after being immersed in: Solution K: ………………………………………. Solution L: ……………………………………….. [2 marks] (b) Explain why solution M is important to ensure the red blood cells able to function efficiently. ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… [2 marks] (c) Compare the condition of the red blood cells in 0.1M and distilled water and 0.50M of sodium chloride solution. [5 marks] ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………….. ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………….. ………………………………………………………………………………………………… ………………………………………………………………………………………………….. Diagram 2.2
3.3 Movement of Substances Across a Plasma Membrane in Living Organisms 12 May 2022 4 EFFECT OF ISOTONIC, HYPOTONIC AND HYPERTONIC SOLUTION ON PLANT CELLS 1.0 M sucrose solution _____________________ 0.5 M sucrose solution _______________________ Distilled water ______________________ ▪ 1.0M sucrose solution is hypertonic to the cell sap of the plant cells. ▪ 0.5M sucrose solution is isotonic to the cell sap of the plant cells. ▪ Distilled water is hypotonic to the cell sap of the plant cells. ▪ Water diffuses out of cell by osmosis ▪ No net movement of water across the plasma membrane ▪ Water diffuses into and out of the cell by osmosis at the same rate ▪ Water diffuses into the cell by osmosis ▪ Cell plasmolysed // Plasmolysis occurs ▪ Both vacuole and cytoplasm lose water and shrink. The plasma membrane pulls away from the cell wall. ▪ Plant leaves and stems to bend downwards and wilts ▪ Cells become flaccid; ▪ Plant cells neither gain nor lose water by osmosis ▪ Vacuole expands, swells up and pushes the cytoplasm and plasma membrane against cell wall. ▪ Turgor pressure of plant cells give support and maintain the shape of cell. ▪ Plant cells becomes shrink and plasmolysed ▪ Plant cells become flaccid ▪ Plant cells becomes turgid and firm 2. Diagram 3 shows two strips of mustard green stem after 20 minutes immersed into two different solutions P and Q. Epidermal layer Lapisan epidermis Epidermal layer Lapisan epidermis Epidermal layer Lapisan epidermis Epidermal layer Lapisan epidermis
3.3 Movement of Substances Across a Plasma Membrane in Living Organisms 12 May 2022 5 (a) Based on the Diagram 3, state the type of solution Q: ………………………………. [1 mark] (b) Explain how the solution Q affects the condition of the cells in the strip that have been immersed. ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… [2 marks] (c) If strip from solution Q is transferred into solution P, explain what will happen to the cells in the strip after 20 minutes. ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… …………………………………………………………………………………………………. [3 marks]