Provide answers to the following questions about excretion, grafting, and laboratory rules.

Here are the answers to the questions:

1. (a) (i) Three substances excreted from the human body are:

• Urine
• Sweat
• Carbon dioxide

1. (a) (ii) Two organs in humans which perform excretory function are:

• Kidneys
• Lungs

1. (b) (i) Grafting in crop production is a horticultural technique where tissues of plants are joined so as to continue their growth together. The upper part of the combined plant (the scion) grows on the root system of the lower part (the rootstock).

1. (b) (ii) Three benefits of grafting are:

• It allows for the propagation of desirable varieties that do not root easily from cuttings.
• It can combine the desirable traits of two plants, such as disease resistance from the rootstock and high fruit yield from the scion.
• It can accelerate the fruiting or flowering of a plant.

1. (c) (i) Two ways in which scientific methods are important are:

• They provide a systematic approach to understanding the natural world, leading to reliable knowledge.
• They allow for the development of new technologies and solutions to practical problems.

1. (c) (ii) Reasons for the following laboratory rules:

• (α) Do not wear rubber slippers to the laboratory: Rubber slippers offer poor protection against chemical spills or falling objects and can be slippery, leading to accidents.
• (β) Close all taps before leaving the laboratory: This prevents water wastage and potential flooding in the laboratory.
• (γ) Spilled liquids must be cleaned immediately: This prevents slips and falls, and minimizes exposure to potentially hazardous chemicals.

1. (d) (i) Earthing in household wiring is the process of connecting the metallic casing of an electrical appliance to the earth (ground) using a low-resistance wire. This provides a safe path for current to flow directly to the earth in case of an insulation fault, preventing electric shock.

1. (d) (ii) Two sources of electric power generation are:

• Thermal power plants (e.g., burning coal, natural gas)
• Hydroelectric power plants (using water flow)