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Question 1Group 4 subjects (technical and applied subjects)

In a Kenya Certificate of Secondary Education agriculture practical, a learner tests soil texture by shaking a soil sample with water in a jar and allowing it to settle. Which result best indicates a clay-rich soil?

  1. Organic matter floats and no mineral layers form at all
  2. The water remains permanently cloudy with all particles in suspension
  3. A thin sand layer forms, then a deep, slowly settling fine layer with clear water above Correct answer.
  4. A thick layer of coarse sand settles first and dominates the profile

Explanation

In the jar sedimentation test, coarse sand settles within minutes, silt follows after hours, and clay stays in suspension longest before forming the thickest final layer. A clay-rich sample therefore shows only a thin sand layer and a deep fine-textured layer that clears slowly. This ordering reflects differences in particle size and settling velocity.

Question 2Group 4 subjects (technical and applied subjects)

A student is asked to select the most suitable wood for making a school laboratory stool that must resist splitting when nails are driven near the edge. Which property matters most?

  1. Low density and high porosity
  2. Straight grain with good cleavage resistance Correct answer.
  3. Bright colour and attractive figure
  4. High shrinkage on drying

Explanation

Nailing near an edge causes splitting when the grain runs out or the wood cleaves easily, so straight-grained timber with good resistance to splitting is chosen. Shrinkage affects dimensional stability after drying, while colour and porosity do not govern nail-holding near edges. The key service requirement is resistance to splitting under impact.

Question 3Group 4 subjects (technical and applied subjects)

In technical drawing, which line type is correctly used to show a hidden internal feature of a machined block?

  1. A continuous thick line
  2. A continuous wavy thin line
  3. A long-dash-dot thin line
  4. A short-dashed line of medium thickness Correct answer.

Explanation

Hidden edges and outlines are drawn with short dashes of medium thickness so they are distinct from visible outlines. Continuous thick lines show visible edges, while long-dash-dot lines mark centre lines. Wavy thin lines indicate break or limit boundaries.

Question 4Group 4 subjects (technical and applied subjects)

A home science learner is planning a meal and wants to retain the maximum vitamin C in vegetables. Which preparation and cooking method is most appropriate?

  1. Cut into large pieces and steam quickly with little water Correct answer.
  2. Chop finely and soak in water for an hour before boiling
  3. Boil in plenty of water and discard the water
  4. Add bicarbonate of soda to keep the colour bright

Explanation

Vitamin C is water-soluble, heat-labile and easily oxidised, so large pieces, minimal water, short cooking time and steaming all reduce losses. Soaking and discarding cooking water leach the vitamin away, and bicarbonate of soda increases its destruction in alkaline conditions. Steaming with little water is therefore the best option.

Question 5Group 4 subjects (technical and applied subjects)

In a basic electrical installation, a fuse is connected in the live conductor. What is the main purpose of this arrangement?

  1. To break the circuit when current exceeds the rated value Correct answer.
  2. To provide an earth path for leakage current
  3. To increase the current reaching the appliance
  4. To convert alternating current to direct current

Explanation

A fuse contains a thin element that melts when current exceeds its rating, thereby breaking the circuit and protecting wiring and appliances from overheating. It is placed in the live conductor so that the circuit is isolated from the supply when it operates. It does not change current direction or provide earthing.

Question 6Group 4 subjects (technical and applied subjects)

A metalwork learner wants to mark a centre point on a steel plate before drilling. Which tool is most suitable for this task?

  1. A hacksaw
  2. A file
  3. A centre punch Correct answer.
  4. A cold chisel

Explanation

A centre punch is struck with a hammer to make a small conical indentation that guides the drill point and prevents it wandering. A cold chisel cuts metal, a file smooths surfaces and a hacksaw cuts sections, none of which produce a drilling guide. Marking the centre accurately is essential for correct hole location.

Question 7Group 4 subjects (technical and applied subjects)

In building construction, which function is performed by a damp-proof course in a wall?

  1. It carries the weight of the roof down to the foundation
  2. It binds bricks together into a solid mass
  3. It prevents moisture rising through the wall by capillary action Correct answer.
  4. It provides a decorative finish to the external wall

Explanation

A damp-proof course is a moisture-resistant layer built into the wall near ground level to stop water rising by capillary action into the structure above. Mortar binds masonry units, the foundation transmits loads, and rendering or paint provides finish. Each element serves a distinct structural or protective role.

Question 8Group 4 subjects (technical and applied subjects)

A student records the mass of a metal block as 54 g and its volume as 20 cm³. What is the density of the metal?

  1. 2.7 g/cm³ Correct answer.
  2. 1080 g/cm³
  3. 0.37 g/cm³
  4. 34 g/cm³

Explanation

Density is mass divided by volume, so 54 g divided by 20 cm³ gives 2.7 g/cm³. This value is consistent with aluminium, a common metal used in school workshops. The other figures arise from dividing or multiplying the given values incorrectly.

Question 9Group 4 subjects (technical and applied subjects)

In a crop production lesson, a farmer notices that maize plants are stunted with purplish leaves and poor root development. Which nutrient deficiency is most likely?

  1. Calcium
  2. Phosphorus Correct answer.
  3. Nitrogen
  4. Potassium

Explanation

Phosphorus deficiency typically causes stunted growth, poor root development and a purplish tinge on leaves and stems because phosphorus is involved in energy transfer and root establishment. Nitrogen deficiency mainly causes general yellowing of older leaves, while potassium deficiency shows scorched leaf margins. Recognising these symptom patterns guides correct fertiliser choice.

Question 10Group 4 subjects (technical and applied subjects)

A learner connects two 6-ohm resistors in parallel across a 12 V supply. What is the total current drawn from the supply?

  1. 6 A
  2. 1 A
  3. 4 A Correct answer.
  4. 2 A

Explanation

Two equal resistors in parallel have an equivalent resistance of half one resistor, giving 3 ohms. Using current equals voltage divided by resistance, 12 V divided by 3 ohms gives 4 A. Adding the branch currents of 2 A each confirms the same total.

Question 11Group 4 subjects (technical and applied subjects)

A technical drawing shows a rectangular block 60 mm long, 40 mm wide and 20 mm high. Which view is obtained by looking at the block from directly above?

  1. A square 20 mm by 20 mm
  2. A rectangle 40 mm by 20 mm
  3. A rectangle 60 mm by 40 mm Correct answer.
  4. A rectangle 60 mm by 20 mm

Explanation

The view from above, called the plan, shows the length and width of the object, so the rectangle measures 60 mm by 40 mm. The height appears only in front and side elevations. Confusing plan with elevation is a common source of error in orthographic projection.

Question 12Group 4 subjects (technical and applied subjects)

A cook wants to thicken a white sauce without forming lumps. Which method gives the most reliable smooth result?

  1. Stirring cornflour into the finished sauce after it has cooled
  2. Mixing flour with melted fat to form a roux before adding milk gradually Correct answer.
  3. Adding all the milk at once to flour and then boiling rapidly
  4. Adding dry flour directly to hot milk and stirring vigorously

Explanation

Making a roux coats the starch granules in fat, which separates them so they disperse evenly when liquid is added gradually, preventing lumps. Adding dry flour to hot liquid causes the starch to gelatinise on the outside and clump. Gradual liquid addition and steady heating allow uniform gelatinisation.

Question 13Group 4 subjects (technical and applied subjects)

In livestock production, a poultry farmer wants to improve egg production during a period of short daylight. Which management practice is most directly effective?

  1. Providing artificial lighting to extend day length Correct answer.
  2. Increasing the fibre content of the feed
  3. Withholding water for part of the day
  4. Reducing the number of birds in the house

Explanation

Day length influences the hormonal control of egg laying, so extending light hours with artificial lighting stimulates the reproductive cycle and raises egg output. Feed quality matters, but extra fibre alone does not trigger laying. Reducing stocking or withholding water would not stimulate production.

Question 14Group 4 subjects (technical and applied subjects)

A student is asked to cut an internal thread in a metal nut by hand. Which sequence of tools is correct?

  1. Centre punch and scriber after drilling
  2. Die and die stock after turning the workpiece down
  3. Tap wrench and tap after drilling a tapping-size hole Correct answer.
  4. File and hacksaw after marking out

Explanation

Internal threads are cut with a tap held in a tap wrench, after first drilling a hole sized to the tapping drill for that thread. Dies and die stocks cut external threads on rods or bolts. Files and hacksaws shape or cut stock but do not form screw threads.

Question 15Group 4 subjects (technical and applied subjects)

A farmer applies a compound fertiliser labelled 23:23:0. Which statement correctly describes the nutrient content?

  1. It contains equal parts of all three major nutrients
  2. It contains 23% nitrogen, 23% potassium and no phosphorus
  3. It contains 23% nitrogen, 23% phosphorus as P2O5 and no potassium Correct answer.
  4. It contains 23% potassium, 23% calcium and no nitrogen

Explanation

Fertiliser grades are quoted in the order nitrogen, phosphorus expressed as phosphorus pentoxide, and potassium expressed as potassium oxide. A 23:23:0 grade therefore supplies nitrogen and phosphorus but no potassium. Knowing this order allows a farmer to select a blend matching a soil test.

Question 16Group 4 subjects (technical and applied subjects)

In a workshop, a learner needs to file a curved surface smoothly. Which technique is most appropriate?

  1. Using a rocking forward-and-sideways stroke while turning the work Correct answer.
  2. Using a hacksaw to remove the curve first
  3. Applying heavy pressure in one direction only
  4. Using only the file edge with a straight push

Explanation

Filing a convex curve requires a rocking motion that combines forward travel with sideways movement while the workpiece is rotated, so the file follows the contour evenly. Straight strokes on a curved surface produce flats, and a hacksaw is not a shaping tool for curves. Light, controlled pressure gives a smoother finish than heavy single-direction strokes.

Question 17Group 4 subjects (technical and applied subjects)

A building apprentice mixes mortar for bricklaying. Which combination of ingredients is correct for a standard cement mortar?

  1. Cement, coarse aggregate and water
  2. Cement, sand and water Correct answer.
  3. Cement, sand, coarse aggregate and water
  4. Lime, coarse aggregate and water

Explanation

Cement mortar consists of cement, fine aggregate such as sand, and water, which together set to bind masonry units. Coarse aggregate is added to make concrete, not mortar. Lime may be included as a plasticiser but is not the essential binding ingredient.

Question 18Group 4 subjects (technical and applied subjects)

A student is testing the strength of a food sample by holding it and observing how it breaks. Which food property is being assessed?

  1. Texture Correct answer.
  2. Aroma
  3. Colour
  4. Flavour

Explanation

Texture describes the physical feel and behaviour of food in the mouth or hand, including hardness, chewiness and how it breaks. Sensory tests for flavour, colour and aroma rely on taste, sight and smell respectively. Observing how a sample breaks is therefore a texture assessment.

Question 19Group 4 subjects (technical and applied subjects)

A metal bar of length 2 m is heated and expands by 2.4 mm. If the coefficient of linear expansion is 1.2 x 10^-5 per degree Celsius, what temperature rise was applied?

  1. 50 degrees Celsius
  2. 10 degrees Celsius
  3. 200 degrees Celsius
  4. 100 degrees Celsius Correct answer.

Explanation

Expansion equals original length times coefficient times temperature rise. Here 2.4 mm equals 2000 mm times 1.2 x 10^-5 times the rise, giving a rise of 100 degrees Celsius. Rearranging the expansion formula before substituting avoids unit errors, and lengths must be in the same unit.

Question 20Group 4 subjects (technical and applied subjects)

A farmer wants to control a heavy infestation of aphids on a vegetable crop while minimising harm to beneficial insects. Which approach best reflects integrated pest management?

  1. Spraying a broad-spectrum insecticide weekly regardless of pest numbers
  2. Removing all flowering plants from around the field
  3. Increasing nitrogen fertiliser to help the crop outgrow the pests
  4. Applying a selective insecticide only after scouting confirms the pest exceeds the economic threshold Correct answer.

Explanation

Integrated pest management combines monitoring, thresholds and selective control so that chemicals are used only when justified and with least harm to natural enemies. Routine broad-spectrum spraying disrupts beneficials and encourages resistance. Removing flowers and excess nitrogen would not target the aphids effectively.

Question 21Group 4 subjects (technical and applied subjects)

In a domestic wiring circuit, a two-way switch arrangement is required at the top and bottom of a staircase so that a lamp can be controlled from either position. Which component is essential for this?

  1. A single-pole one-way switch at each end
  2. A push-button bell switch at each end
  3. A dimmer switch at each end
  4. A two-way switch at each end with a two-wire strapper between them Correct answer.

Explanation

Staircase lighting uses two two-way switches connected by strapper wires so that operating either switch changes the circuit path and toggles the lamp. One-way switches cannot create the alternate path needed. Dimmers and push buttons do not provide the required changeover function.

Question 22Group 4 subjects (technical and applied subjects)

A learner compares two samples of fabric by burning small threads. One sample smells of burning paper and leaves grey ash, while the other melts and forms a hard bead. Which conclusion is best supported?

  1. Both samples are animal fibres
  2. The first is nylon and the second is wool
  3. The first is cotton and the second is a synthetic fibre such as polyester Correct answer.
  4. Both samples are plant fibres

Explanation

Burning paper smell with grey ash is characteristic of cellulose fibres such as cotton, while melting and forming a hard bead indicates a thermoplastic synthetic fibre like polyester or nylon. Animal fibres such as wool smell of burning hair and form crushable ash. The burn test therefore distinguishes plant from synthetic fibres.

Question 23Group 4 subjects (technical and applied subjects)

A concrete beam is reinforced with steel bars placed near its lower face. Why is this placement chosen for a simply supported beam carrying a downward load?

  1. The lower face is in compression and concrete alone would crack there
  2. Steel expands more than concrete so it must be at the bottom
  3. Concrete is strong in tension and steel is strong in compression
  4. The lower face is in tension and steel resists tensile forces well Correct answer.

Explanation

Under a downward load a simply supported beam sags, putting the lower face in tension and the upper face in compression. Concrete resists compression well but is weak in tension, so steel bars are placed where tension occurs to carry those forces. This is why reinforcement is positioned near the soffit of the beam.

Question 24Group 4 subjects (technical and applied subjects)

A learner is asked to calculate the mechanical advantage of a lever system in which a load of 300 N is lifted by an effort of 75 N. What is the mechanical advantage, and what does it indicate?

  1. 4, indicating the lever multiplies the effort force Correct answer.
  2. 375, indicating the total force in the system
  3. 0.25, indicating the effort is larger than the load
  4. 225, indicating the effort saved in newtons

Explanation

Mechanical advantage equals load divided by effort, so 300 N divided by 75 N gives 4. A value greater than one means the machine allows a small effort to overcome a larger load. The effort moves through a greater distance than the load, so work input is not reduced.

Question 25Group 4 subjects (technical and applied subjects)

During a food preparation practical, a learner wants to prevent enzymatic browning in peeled and sliced bananas before serving. Which treatment is most effective?

  1. Sprinkling the slices with table salt
  2. Coating the slices with lemon juice Correct answer.
  3. Wrapping the slices tightly in dry paper
  4. Heating the slices gently in water then cooling them

Explanation

Enzymatic browning is caused by polyphenol oxidase acting on phenolic compounds in the presence of oxygen. Lemon juice lowers the surface pH, which inhibits the enzyme, and its ascorbic acid also reduces the brown pigments. Blanching would also work by denaturing the enzyme, but gentle heating followed by cooling is not the option described for effective inhibition here.

Question 26Group 4 subjects (technical and applied subjects)

In a technical drawing lesson, a learner is asked to draw the three principal orthographic views of a simple bracket. Which set of views is conventionally arranged on the drawing sheet?

  1. Front elevation, plan and end elevation Correct answer.
  2. Isometric, oblique and perspective views
  3. Freehand sketch, tracing and blueprint
  4. Sectional view, detail view and auxiliary view

Explanation

Orthographic projection presents the object as separate views seen from fixed directions, normally a front elevation, a plan viewed from above and an end or side elevation. These are laid out in a fixed relationship (first-angle or third-angle) so that features align between views. Pictorial and sectional drawings serve other purposes and are not the standard trio of principal views.

Question 27Group 4 subjects (technical and applied subjects)

A carpentry learner is preparing a mortise and tenon joint. Which tool is used to cut the rectangular mortise in the timber?

  1. A mortise chisel struck with a mallet Correct answer.
  2. A smoothing plane pushed along the grain
  3. A try square used to mark a right angle
  4. A tenon saw used to cut across the grain

Explanation

A mortise is a rectangular recess cut into timber, and it is formed with a stout mortise chisel driven by a mallet, often after boring away waste. The chisel's thick blade withstands the levering needed to clear the socket. Planes smooth surfaces, squares mark lines and tenon saws cut shoulders, so none of them removes the socket itself.

Question 28Group 4 subjects (technical and applied subjects)

In a home science practical, a learner is asked to demonstrate the rubbing-in method for making shortcrust pastry. Which procedure correctly describes this method?

  1. Beat eggs into flour to form a smooth pouring batter
  2. Cream fat and sugar together until pale before adding flour
  3. Melt fat in a pan and pour it into the dry ingredients
  4. Rub fat into flour with the fingertips until the mixture resembles breadcrumbs Correct answer.

Explanation

Rubbing-in distributes small pieces of fat through the flour by lifting and rubbing them between the fingertips until the mixture looks like fine breadcrumbs. The fat coats the flour particles, which limits gluten development and gives a short, crumbly texture. The other methods belong to creaming, melting and batter-making respectively.

Question 29Group 4 subjects (technical and applied subjects)

A building construction student is told that a certain concrete mix is specified as 1:2:4. What does this ratio represent?

  1. One part cement to two parts fine aggregate to four parts coarse aggregate Correct answer.
  2. One part water to two parts cement to four parts sand
  3. One part cement to two parts water to four parts coarse aggregate
  4. One part coarse aggregate to two parts cement to four parts sand

Explanation

Concrete mix ratios are given in the order cement : fine aggregate : coarse aggregate by volume. A 1:2:4 mix therefore means one part cement, two parts sand and four parts ballast or coarse aggregate. Water is added separately to give a workable consistency and is not part of this nominal ratio.

Question 30Group 4 subjects (technical and applied subjects)

A metalwork learner is told to anneal a piece of copper before bending it. What does annealing involve?

  1. Cold-working the metal with a hammer to increase hardness
  2. Coating the metal with oil to prevent corrosion
  3. Heating the metal and quenching it rapidly to harden it
  4. Heating the metal and cooling it slowly to soften it Correct answer.

Explanation

Annealing relieves internal stresses and softens a metal so it can be worked further. The metal is heated to a suitable temperature and then allowed to cool slowly, for copper by quenching or air cooling depending on the process. Rapid quenching to harden applies to steel, and hammering is work-hardening, not annealing.

Question 31Group 4 subjects (technical and applied subjects)

A student is asked to identify the part of a flower that develops into the fruit after fertilisation. Which structure is correct?

  1. The sepal
  2. The ovary Correct answer.
  3. The anther
  4. The stigma

Explanation

After fertilisation the ovules inside the ovary become seeds and the ovary wall develops into the fruit. The anther produces pollen, the stigma receives pollen and the sepals protect the bud. Recognising this sequence is basic to crop production and seed saving.

Question 32Group 4 subjects (technical and applied subjects)

A learner is asked to state the unit of electrical resistance and the instrument used to measure it. Which pair is correct?

  1. Ampere, measured with an ammeter
  2. Volt, measured with a voltmeter
  3. Watt, measured with a wattmeter
  4. Ohm, measured with an ohmmeter Correct answer.

Explanation

Resistance is measured in ohms and can be read directly with an ohmmeter or the resistance range of a multimeter. Volts measure potential difference, amperes measure current and watts measure power, each with its own instrument. Matching quantity to unit and instrument is a core skill in electrical technology.

Question 33Group 4 subjects (technical and applied subjects)

In a technical drawing, a dimension of 45 mm is shown on a drawing drawn to a scale of 1:5. What is the actual length of the object?

  1. 9 mm
  2. 225 mm Correct answer.
  3. 50 mm
  4. 450 mm

Explanation

A scale of 1:5 means one unit on the drawing represents five units on the real object, so the drawing is smaller than life. Multiplying the drawn length by the scale factor gives 45 mm x 5 = 225 mm. Dividing instead would give a smaller figure, which is the error to avoid.

Question 34Group 4 subjects (technical and applied subjects)

A cook is preparing a meal and wants to preserve the green colour of vegetables during boiling. Which practice helps most?

  1. Boil slowly for a long time with the lid on
  2. Boil quickly in a large volume of water with the lid off Correct answer.
  3. Add a large quantity of bicarbonate of soda
  4. Soak the vegetables in cold water for an hour before cooking

Explanation

Green vegetables contain pigments that are affected by acids released during cooking and by prolonged heating. Cooking rapidly in plenty of water, uncovered, allows volatile acids to escape and shortens the exposure to heat, so the colour is retained. Adding bicarbonate makes the texture mushy and destroys vitamins, while long slow cooking dulls the colour.

Question 35Group 4 subjects (technical and applied subjects)

A livestock learner is advised to castrate male calves at a young age. What is the main management reason for early castration?

  1. It prevents all infectious diseases in the herd
  2. It reduces aggressive behaviour and improves ease of handling and meat quality Correct answer.
  3. It improves the fertility of the female animals in the herd
  4. It increases the growth rate of the animals beyond that of entire males

Explanation

Castration removes the source of male hormones that cause fighting, mounting and tough meat in older bulls. Early castration makes handling safer and produces more docile, evenly finished animals. It does not boost growth above entire males, prevent all disease or affect the fertility of females.

Question 36Group 4 subjects (technical and applied subjects)

A learner is asked to select the correct electrode for arc welding mild steel plate in a workshop. Which factor is most important in the choice?

  1. The colour of the welding helmet
  2. The length of the earth cable
  3. The type of current supply and the thickness of the metal being welded Correct answer.
  4. The size of the welding table

Explanation

Electrode selection depends on the base metal, its thickness and the welding current available, since the electrode coating and diameter must suit these. A thicker plate needs a larger electrode and higher current to achieve penetration. Helmet colour, cable length and table size do not affect the weld deposit.

Question 37Group 4 subjects (technical and applied subjects)

A building apprentice is asked to explain why a lintel is provided over a doorway in a brick wall. What is its main function?

  1. To provide a decorative finish around the door frame
  2. To carry the weight of the wall above the opening and transfer it to the sides Correct answer.
  3. To hold the door leaf in position when it is closed
  4. To prevent damp rising from the ground into the wall

Explanation

An opening in a wall interrupts the path of the load, so a lintel spans it and carries the masonry above to the supports on either side. It must be strong enough to resist bending without excessive deflection. Damp control is the job of a damp-proof course, and decoration and door hanging are unrelated functions.

Question 38Group 4 subjects (technical and applied subjects)

A student is testing a soil sample in an agriculture practical. The soil forms a long, flexible ribbon when squeezed between the fingers. What does this indicate?

  1. The soil is mostly coarse sand
  2. The soil has a high clay content Correct answer.
  3. The soil is strongly acidic
  4. The soil has a high organic matter content

Explanation

The ribbon test relies on the cohesion of fine clay particles, which allows a moist sample to be moulded into a long flexible ribbon. Sandy soils crumble and will not form a ribbon, while organic matter feels spongy rather than plastic. Acidity is a chemical property and cannot be judged from the ribbon alone.

Question 39Group 4 subjects (technical and applied subjects)

A farmer wants to store dry maize grain safely for several months. Which condition best prevents spoilage?

  1. Storage in direct sunlight with the bags open
  2. High moisture content and warm, humid storage
  3. Sealed damp sacks stacked against a wall
  4. Low moisture content and cool, dry, well-ventilated storage Correct answer.

Explanation

Grain keeps well when it is dried to a safe moisture level and stored where it stays cool, dry and ventilated. Moulds and insects thrive in warm, moist conditions, so damp or humid storage leads to heating, mould and aflatoxin risk. Direct sunlight and open bags allow moisture uptake and pest entry.

Question 40Group 4 subjects (technical and applied subjects)

In a basic electrical circuit, a learner connects a lamp, a switch and a battery in series. What happens when the switch is opened?

  1. The lamp stays lit but becomes brighter
  2. The battery reverses its polarity
  3. The lamp flickers on and off continuously
  4. The circuit is broken and the lamp goes out Correct answer.

Explanation

A series circuit provides only one path for current, so opening the switch breaks that path and current stops flowing. With no current the lamp cannot light. Polarity and flickering are not consequences of simply opening a series switch.

Question 41Group 4 subjects (technical and applied subjects)

A home science learner is asked to explain why milk is scalded before making yoghurt. What is the main purpose?

  1. To destroy unwanted micro-organisms so that the starter culture can grow without competition Correct answer.
  2. To increase the fat content of the milk
  3. To make the milk sweeter by converting lactose to sugar
  4. To change the colour of the milk to a creamy white

Explanation

Scalding or pasteurising the milk kills spoilage and pathogenic organisms that would otherwise compete with the starter culture. The milk is then cooled to the correct temperature and inoculated so that the desired bacteria ferment lactose to lactic acid. Scalding does not add fat, sweeten the milk or deliberately alter its colour.

Question 42Group 4 subjects (technical and applied subjects)

A carpentry learner needs to produce a flat, smooth surface on a piece of hardwood. Which tool is most appropriate for the final finishing cut?

  1. A smoothing plane Correct answer.
  2. A marking gauge
  3. A brace and bit
  4. A rip saw

Explanation

A smoothing plane takes a fine shaving and is used after jack planing to produce a flat, smooth surface ready for finishing. Saws cut timber to size, braces bore holes and marking gauges scribe lines. Choosing the right tool for the finishing stage is a key workshop skill.

Question 43Group 4 subjects (technical and applied subjects)

A student is asked to explain why a fuse is connected in the live wire of a domestic circuit. What is the correct reason?

  1. It increases the voltage supplied to the appliances
  2. It stores electrical energy for use during power cuts
  3. It converts alternating current to direct current
  4. It melts and breaks the circuit when excessive current flows, protecting the wiring Correct answer.

Explanation

A fuse is a deliberate weak point that melts when current exceeds its rating, isolating the faulty circuit before the cable overheats. Placing it in the live wire ensures the circuit is disconnected from the supply when it operates. Fuses do not change voltage, rectify current or store energy.

Question 44Group 4 subjects (technical and applied subjects)

A cook is making a fruit salad and wants to prevent the cut apples from turning brown. Which action is most effective?

  1. Boil the fruit pieces in water for ten minutes
  2. Toss the cut fruit in lemon juice before serving Correct answer.
  3. Leave the cut fruit uncovered at room temperature
  4. Sprinkle the fruit with table salt

Explanation

Browning is caused by the enzyme polyphenol oxidase acting on the fruit in the presence of oxygen. Lemon juice lowers the pH and the ascorbic acid reduces the reaction, slowing browning. Leaving fruit exposed, salting it or boiling it does not protect the colour and may spoil the texture or flavour.

Question 45Group 4 subjects (technical and applied subjects)

A technical drawing learner is asked to draw the development of a cylinder. Which shape is obtained?

  1. A rectangle whose width equals the circumference of the cylinder Correct answer.
  2. A circle equal to the base of the cylinder
  3. A triangle with sides equal to the height
  4. A trapezium with parallel sides equal to the diameter

Explanation

When the curved surface of a cylinder is unrolled, it forms a rectangle. The length of the rectangle equals the circumference of the base (pi times diameter) and the height equals the height of the cylinder. The base and top are separate circles added to the development.

Question 46Group 4 subjects (technical and applied subjects)

A farmer notices that a crop shows yellowing between the veins of older leaves first. Which nutrient deficiency is most likely?

  1. Phosphorus
  2. Calcium
  3. Magnesium Correct answer.
  4. Nitrogen

Explanation

Magnesium is a mobile nutrient and forms the centre of the chlorophyll molecule, so deficiency shows as interveinal chlorosis on older leaves first as the plant moves magnesium to new growth. Nitrogen deficiency causes general yellowing of older leaves, while phosphorus gives purple tints and calcium affects new growth.

Question 47Group 4 subjects (technical and applied subjects)

A building student is asked why reinforcement bars in a simply supported concrete beam are placed near the bottom. Which explanation is correct?

  1. The lower face is in tension, and concrete is weak in tension Correct answer.
  2. The bars prevent the beam from expanding in hot weather
  3. The bars reduce the weight of the beam
  4. The lower face is in compression, and steel resists compression best

Explanation

Under downward loading a simply supported beam sags, putting the bottom fibres in tension and the top in compression. Concrete is strong in compression but weak in tension, so steel bars are placed where tension occurs to carry it. Steel does not reduce weight, and thermal expansion is handled by joints.

Question 48Group 4 subjects (technical and applied subjects)

A learner is calculating the efficiency of a pulley system. The load of 400 N is raised through 1 m while the effort of 100 N moves through 5 m. What is the efficiency?

  1. 80% Correct answer.
  2. 20%
  3. 500%
  4. 125%

Explanation

Efficiency equals useful work output divided by work input, expressed as a percentage. Output work is 400 N x 1 m = 400 J and input work is 100 N x 5 m = 500 J, so efficiency is 400/500 x 100 = 80%. The velocity ratio is 5 and the mechanical advantage is 4, which confirms the result.

Question 49Group 4 subjects (technical and applied subjects)

A learner is asked to explain why a capacitor is connected across the terminals of a small d.c. motor in a circuit. Which explanation is best?

  1. It increases the running speed of the motor permanently
  2. It stores enough energy to run the motor for several hours
  3. It suppresses sparking at the brushes by absorbing sudden changes in current Correct answer.
  4. It changes the motor from d.c. to a.c. operation

Explanation

When the brushes break contact with the commutator, the motor's inductance tries to maintain current and produces a high voltage that causes sparking. A capacitor across the terminals provides a path for this transient current and suppresses the spark, reducing radio interference and brush wear. It does not change the motor's supply or store useful running energy.

Question 50Group 4 subjects (technical and applied subjects)

In a food technology lesson, a learner is asked why salt is added when preserving meat by curing. Which explanation is correct?

  1. It neutralises all acids present in the meat
  2. It draws water out of the tissue and inhibits the growth of spoilage micro-organisms Correct answer.
  3. It provides a source of carbohydrate for the meat
  4. It raises the water content of the meat so that it stays moist

Explanation

Salt lowers the water activity of meat by drawing moisture out through osmosis, which deprives micro-organisms of the water they need to grow. This is why curing extends shelf life, often together with nitrites and drying. Salt does not add moisture, neutralise acids or supply carbohydrate.