Identify excretory substances and organs. Explain grafting and its benefits. Discuss the importance of scientific methods and lab rules.

Hey Caci — ready when you are. Here are the solutions to the questions from the image: 1. (a) (i) Three substances excreted from the human body are: Urea* Carbon dioxide* Water* (as sweat or urine) (ii) Two organs in humans which perform excretory function are: Kidneys* Lungs* 1. (b) (i) Grafting* is used in crop production as a horticultural technique where tissues of plants are joined so as to continue their growth together. It is often used to combine desirable traits from two different plants. (ii) Three benefits of grafting are: It allows for faster fruiting* or flowering compared to growing from seed. It can confer disease resistance* or pest resistance by using a resistant rootstock. It enables the cultivation of plants in unsuitable soil conditions* by using a rootstock adapted to those conditions. 1. (c) (i) Two ways in which scientific methods are important are: They provide a systematic approach to solving problems* and making discoveries. They help in developing new technologies* and improving existing ones. (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, and to prevent slipping. (β) Close all taps before leaving the laboratory: To prevent water wastage* and potential flooding. (γ) Spilled liquids must be cleaned immediately: To prevent accidents* like slipping, and to avoid contamination or damage to equipment/surfaces. 1. (d) (i) Earthing* in household wiring is the process of connecting the metal casing of an electrical appliance to the ground (earth) using a low-resistance wire. This provides a safe path for current to flow to the earth in case of an electrical fault, preventing electric shock. (ii) Two sources of electric power generation are: Hydroelectric power* (from water) Thermal power* (from burning fossil fuels like coal or natural gas) 2. (a) Four reasons why farmers should be discouraged from using chemical fertilizers: They can lead to environmental pollution*, such as eutrophication of water bodies when runoff occurs. Overuse can cause soil degradation*, reducing its natural fertility and beneficial microbial life. They can be expensive* for farmers, increasing production costs. Improper handling or application can pose health risks* to farmers and consumers. 2. (b) (i) Temporary hard water* is water that contains dissolved hydrogen carbonates of calcium and magnesium. It can be softened by boiling. (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) 2. (c) (i) 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 its direction. (ii) Explanation of terms as applied to simple machines: (α) Mechanical advantage*: This is the ratio of the output force (load) to the input force (effort). It indicates how much a machine multiplies the force applied to it. (β) Velocity ratio*: This is the ratio of the distance moved by the effort to the distance moved by the load in the same amount of time. 2. (d) (i) Food processing* is the transformation of raw agricultural products into food, or of food into other forms, for consumption by humans or animals. It involves various physical and chemical operations. (ii) State: (α) Two advantages of food processing: It preserves food*, extending its shelf life and reducing spoilage. It increases convenience* for consumers, making food easier and quicker to prepare. (β) One disadvantage of food processing: It can lead to the loss of essential nutrients* (e.g., vitamins) during processing. Drop the next question.