Question 1: Define xylem and explain its primary function in plants.

Answer: Xylem is a type of vascular tissue in plants responsible for transporting water and minerals from roots to the rest of the plant.

Question 2: Describe how the structure of xylem vessels facilitates their function in water conduction.

Answer: Xylem vessels are elongated, hollow tubes made of dead cells with thick, lignified walls that prevent collapse and allow efficient water transport through capillary action and transpiration pull.

Question 3: Define phloem and describe its main role in plants.

Answer: Phloem is a vascular tissue responsible for transporting sugars and organic nutrients produced by photosynthesis from the leaves to other parts of the plant.

Question 4: Explain the mechanism by which phloem transports sugars throughout the plant.

Answer: Phloem transports sugars via a process called translocation, which involves active loading of sugars into phloem sieve tubes at source regions, creating a pressure gradient that drives flow towards sink regions where sugars are used or stored.

Question 5: Calculate the rate of water transport if a xylem vessel moves 0.05 litres of water in 10 minutes. Express your answer in litres per minute.

Answer: Rate = Volume / Time = 0.05 litres / 10 minutes = 0.005 litres per minute.

Question 6: Identify three variables that could affect the rate of translocation in phloem tissues.

Answer: Variables include the pressure gradient within the phloem, the concentration of sugars at source and sink areas, and the temperature affecting the viscosity of the sap.

Question 7: Outline a practical experiment to investigate the effect of temperature on the rate of water movement in xylem vessels.

Answer: A student could set up a capillary tube immersed in water with a heat source applied at one end, measure the height of water rise at different temperatures, and record the time taken for water to reach certain heights, ensuring safety precautions like using heat-resistant gloves.

Question 8: Describe two safety precautions that should be observed during experiments involving plant tissues and laboratory equipment.

Answer: Ensure the use of gloves and eye protection when handling chemicals or heated equipment, and handle glassware carefully to prevent breakage and injury.

Question 9: A farmer notices that the transport of nutrients in their crops is slow during cold weather. Explain the reason based on the structure and function of xylem and phloem.

Answer: Cold weather reduces the rate of transpiration and metabolic processes, leading to decreased water and nutrient movement in xylem and slower translocation of sugars in phloem. The viscosity of sap increases at lower temperatures, impeding flow.

Question 10: In what ways are xylem and phloem adapted to their functions in terms of structure and location within plant stems?

Answer: Xylem vessels are thick-walled, lignified, and located centrally to withstand pressure; phloem is located near the surface with sieve tubes that are flexible for translocation. Both are arranged in vascular bundles to optimise transport efficiency.

Question 11: Explain how the structure of plant vascular tissues contributes to their ability to transport water and nutrients efficiently.

Answer: The lignified, hollow, and elongated structure of xylem allows for unimpeded water flow and provides mechanical support. Phloem's sieve tubes and companion cells facilitate active and passive transport of organic nutrients, enabling efficient distribution across the plant.