Outline the excretory functions of the human body, the benefits of grafting in crop production, and the importance of scientific methods.

Here are the solutions to the questions: 1. a) (i) Three substances that are excreted from the human body: • Urine • Sweat • Carbon dioxide (ii) Two organs in humans which perform excretory function: • Kidneys • Lungs (also Skin, Liver) b) (i) Grafting is used in crop production to join parts of two plants (a scion and a rootstock) so that they grow as one plant. This technique is used to combine desirable traits from different plants, such as disease resistance from the rootstock and high yield from the scion. (ii) Three benefits of grafting: • Allows for the propagation of plants that do not readily root from cuttings. • Can improve disease and pest resistance by using a resistant rootstock. • Enables the production of fruit earlier than from seed-grown plants. • Can combine desirable characteristics from two different plants into one. c) (i) Two ways in which scientific methods are important: • It provides a systematic approach to investigate phenomena, ensuring that conclusions are based on empirical evidence and logical reasoning. • It allows for the development of new technologies and solutions to real-world problems through experimentation and observation. (ii) One reason for each of the following laboratory rules: (α) Do not wear rubber slippers to the laboratory: To protect feet from chemical spills, broken glass, or heavy falling objects. Rubber slippers offer inadequate protection and can be slippery. (β) Close all taps before leaving the laboratory: To prevent water wastage and potential flooding in the laboratory. (γ) Spilled liquids must be cleaned immediately: To prevent accidents such as slips and falls, and to avoid contamination or damage to equipment and surfaces. d) (i) Earthing as used in household wiring: Earthing (or grounding) is a safety measure in electrical wiring where the metal casing of an appliance is connected to the Earth via a low-resistance wire. This provides a safe path for fault current to flow directly to the ground in case of an electrical fault, preventing electric shock. (ii) Two sources of electric power generation: • Hydroelectric power (from water) • Thermal power (from burning fossil fuels like coal, oil, gas) • Solar power (from sunlight) • Wind power (from wind turbines) • Nuclear power (from nuclear fission) 2. a) Four reasons why farmers should be discouraged from using chemical fertilizers: • Environmental pollution: Runoff from chemical fertilizers can contaminate water bodies, leading to eutrophication and harming aquatic life. • Soil degradation: Overuse can alter soil pH, reduce beneficial microbial activity, and decrease long-term soil fertility. • Health risks: Exposure to certain chemical fertilizers can pose health risks to farmers and consumers. • Cost: Chemical fertilizers can be expensive, increasing production costs for farmers. • Reduced biodiversity: Can harm non-target organisms in the soil and surrounding environment. b) (i) Temporary hard water: Temporary hard water is water that contains dissolved calcium bicarbonate (Ca(HCO_3)_2) and/or magnesium bicarbonate (Mg(HCO_3)_2). It can be softened by boiling, which causes the bicarbonates to decompose and precipitate as insoluble carbonates. (ii) Chemical equation to show how temporary hard water can be softened by heating: Ca(HCO_3)_2(aq) heat CaCO_3(s) + H_2O(l) + CO_2(g) c) (i) What is a lever? A lever is a simple machine consisting of a rigid bar that pivots around a fixed point called a fulcrum. It is used to multiply force or change the direction of force. (ii) Explanation of terms as applied to simple machines: (α) Mechanical advantage: The ratio of the output force (load) to the input force (effort). It indicates how much a machine multiplies the force applied to it. Mechanical Advantage (MA) = LoadEffort (β) Velocity ratio: The ratio of the distance moved by the effort to the distance moved by the load in the same time. It is a theoretical value that depends only on the geometry of the machine. Velocity Ratio (VR) = Distance moved by effortDistance moved by load d) (i) What is food processing? Food processing is the transformation of raw ingredients into food, or of food into other forms, through physical or chemical means. It involves various techniques to prepare, preserve, and package food products for consumption. (ii) State: (α) Two advantages of food processing: • Increases shelf life and prevents spoilage, making food available for longer periods and in different seasons. • Enhances food safety by eliminating harmful microorganisms and toxins. • Adds convenience by making food easier and quicker to prepare. • Improves nutritional value through fortification or enrichment. (β) One disadvantage of food processing: • Can lead to loss of nutrients (e.g., vitamins) during processing. • Processed foods often contain high levels of salt, sugar, or unhealthy fats. • May involve the use of additives and preservatives that some consumers prefer to avoid. That's 2 down. 3 left today — send the next one.