AGRICULTURAL TECHNOLOGY
GRADE 12
NATIONAL SENIOR CERTIFICATE EXAMINATIONS
MAY/JUNE 2021

SECTION A

QUESTION 1

1.1

1.1.1   C✓✓ (2)
1.1.2   D✓✓ (2)
1.1.3   C✓✓ (2)
1.1.4   A✓✓ (2)
1.1.5   B✓✓ (2)
1.1.6   D✓✓ (2)
1.1.7   B✓✓ (2)
1.1.8   D✓✓ (2)
1.1.9   B✓✓ (2)
1.1.10 C✓✓ (2)
[20]

1.2

1.2.1  Stress/Depression/anxiety✓✓  (2)
1.2.2  Gearbox/Gears/Transmission✓✓  (2)
1.2.3  Magnetism/decrease rusting✓✓  (2)
1.2.4  Explosion/Fire✓✓  (2)
1.2.5  Simultaneously/together/All at once✓✓  (2)
[10]

1.3

1.3.1  F✓✓  (2)
1.3.2  A✓✓  (2)
1.3.3  C✓✓  (2)
1.3.4  D✓✓  (2)
1.3.5  B✓✓  (2)
(5 x 2) 
[10

TOTAL SECTION A: 40

SECTION B
QUESTION 2: MATERIALS AND STRUCTURES

2.1

2.1.1 A metal that will be used to supply warm water.

Copper.✓ (1)

2.1.2 The reason why Copper will be the best suited for warm water pipes.

No corrosion/rust.✓ (1)

2.1.3 The joining method that will be used to permanently join two Copper pipes.

Soldering.✓ (1)

2.1.4 The material that will be best to transport milk in a dairy system.

Stainless steel.✓ (1)

2.1.5 A reason why stainless steel will be the best metal.

The steel is resistant to air, water and many chemicals used for cleaning/Corrosion resistant/Hygienic/does not contaminate food.✓ (1)

2.1.6 A method used to permanently join stainless steel.

Welding/TIG welding.✓ (1)

2.1.7 The best metal used for the manufacturing of a farm gate.

Mild steel.✓ (1)

2.1.8 The substance that can corrode copper.

Acids/Ammonium/Heavy metal salts/Sulphur.✓ (1)

2.1.9 A metal that is commonly used in the food industry for food storing purposes.

Aluminum.✓ (1)

2.2 THREE preparation procedures to ensure a sufficient PVC pipe welding joint.

Make sure the joint is clean.✓
Make sure the joint is dry.✓
Sand both the joint with sandpaper.✓
(3)

2.3

2.3.1 Description of the earth leakage system of the electrical fence.

• There must be an earth spike to the ground to complete the circuit between the ground and the fence.✓
• The animal or person will complete the circuit and get shocked.✓
• Plant material will influence the circuit and must be removed.✓
• Inspect the fence, isolators and connections frequently to prevent short circuit.✓
• Run an earth return line parallel to the fence line on long distance fences.✓
• Connect with earth spikes on a regular basis to improve the efficiency.✓
  (6)

2.3.2 The type of wire that may never be used to erect an electric fence.

• Razor wire.✓
• Barbed wire.✓
  (Any 1) (1)

2.3.3 TWO daily activities that the farmer must perform to properly maintain an electric fence.

• Clean plants that is touching the fence.✓
  Look for damaged or broken wires, isolators or loose connections and repair.✓
  (2)

2.4 Recommendations for the use of Vesconite when manufacturing bushes.

• Easy to install or to remove.✓
• Does not corrode and is non-conductive.✓
• Will not wear shafts.✓
• Resistant to a wide range of chemicals.✓
• Cheap to manufacture.✓
  (5)

2.5 ONE electrical property of Teflon and a reason for the answer.

• It has a high di-electric capacity.✓
• Reason: Electricity don’t have an influence on this material.✓ (2)

2.6 FIVE properties of safety screens on a combine harvester.

• Light.✓
• Safeguard the user.✓
• Not vibrate or become loose.✓
• Sturdy/Strong.✓
• Keep out all undesired material.✓
  (5)

2.7 TWO reasons for the use of brass instead of copper in the manufacturing of electrical connections.

• Hardness.✓
• Strength.✓
• Machinability.✓
• Wear resistance.✓
• Ductility.✓ (Any 2) (2)
  [35]

QUESTION 3: ENERGY

3.1 TWO alternative energy sources that make use of a turbine and a generator to generate electricity.

• Wind.✓
• Geothermal.✓
• Hydro.✓
  (Any 2) (2)

3.2

3.2.1 The number of systems that you will need to provide sufficient power to a 6 kw submersible pump.

Two.✓ (1)

3.2.2 Determine whether the panels should be connected in parallel or series and a reason for the answer.

Series.✓ Because a connection in series will increase the kw/power twice.✓ (2)

3.2.3 ONE Reason for the use of silicon in the manufacturing of the solar cells.

• Is a semi conductive material.✓
• Can withstand the temperature of the sun.✓
• Don't conduct heat.✓
• Is water tight/proof.✓
  (Any 1) (1)

3.2.4 The layer of the solar panel that carries negative electrons.

The top layer/N-Type layer.✓ (1)

3.2.5 Measure to ensure that there is electricity available during the night.

Use a battery system for the night.✓ (1)

3.2.6 THREE applications of solar panels on a game farm.

• To provide power to: security cameras.✓
• Alarm systems.✓
• Electric gate motors.✓
• Emergency lights.✓
• Electric fencing.✓
• Borehole pumps.✓
  (Any 3) (3)

3.3 FOUR advantages of geothermal power station.

• No pollution.✓
• The cost of the land to build a geothermal power plant on is usually less expensive.✓
• Clean energy.✓
• Tax cuts.✓
• No fuel is used to generate electricity.✓
• Low running cost.✓
  (Any 4) (4)

3.4 FOUR factors that must be considered when installing a small wind turbine on a farm.

• Must be in an open space/field.✓
• Flat area.✓
• The absence of obstacles like trees/forests/hills/mountains.✓
• The presence of strong and frequent winds.✓
• A location further from a village or residential site.✓
• Location away from suburbs. ✓
• Not harmful to bird life or nature. ✓
  (Any 4) (4)

3.5 Process used to manufacture ethanol.

Related Items

• Distillation.✓ (1)
  [20]

QUESTION 4: SKILLS AND CONSTRUCTION PROCESSES

ILLUSTRATION	NAME OF THE WELDING DEFECT	GIVE THE POSSIBLE CAUSES
.	4.1.1 Porosity.✓	4.1.2 Blocked nozzle.✓ Gas flow too low or too high.✓ Leaking gas lines.✓ Draught conditions.✓ Nozzles distance from the work is too great.✓ Painted, wet or oily plate.✓ Wet or rusty electrode/wire.✓ (Any 1)
.	4.1.3  Spatter.✓	4.1.4 Voltage too low.✓ Inadequate inductance✓ Rusty or dirty plate.✓ (Any 1)
.	4.1.5  Undercut.✓	4.1.6 Welding speed too fast.✓ Current too high.✓ Poor technique.✓
.	4.1.7 Lack of fusion.✓	4.1.8 Amps too low.✓ Irregular surface.✓ Wrong torch angle.✓ (Any 1)

4.2 MIG welding labels for the numbers A–D as indicated.
A – Molten puddle.✓
B – Contact tip.✓
C – Welding wire/Electrode.✓
D – Shielding gas.✓ (4)

4.3

4.3.1 TWO materials that can be cut with oxy-acetylene cutting apparatus.

• Mild steel.✓
• Cast iron.✓
• Stainless steel.✓
  (Any 2) (2)

4.3.2 FIVE steps that must be followed to cut a straight line on a 10mm mild steel sheet using an Oxy-acetylene cutting apparatus.

• Attach an guide iron to the metal sheet next to the place where you want to cut/parrallel to your mark.✓
• Select the appropriate nozzle size.✓
• Light the torch and adjust the required flame.✓
• Bring the material up to red-hot.✓
• Oxygen is then fed with the lever on the cutting attachment.✓
• Move the torch at the required speed along a guide.✓
• The oxygen will blow the melted iron from the cutting area to create a clean cutting line.✓
  (Any 5) (5)

4.3.3 THREE oxy-acetylene welding tips in the overhead welding position.

• Reduced melting pool just big enough to create the wanted penetration.✓
• Reducing the size of the flame.✓
• Use a slightly thicker welding rod.✓
• Use the force of the flame to keep the molten metal in position.✓
  (Any 3) (3)

4.4 Marks will be allocated for the following:

4.5  A gas that can be used with a plasma cutter to remove the melted metal.

• Argon.✓
• Nitrogen.✓
• Oxygen.✓
• Compressed air.✓
  (Any 1) (1)
• 4.6 Comparison in table form of the Inverter welding machine to the MIG welding machine
  

  Inverter welder	MIG welding machine
  Low initial setup cost.✓	High initial setup cost.✓
  Compact.✓	Bulk or large.✓
  Light and easy to handle.✓	Heavy and difficult to handle.✓
  Slag must be removed after welding.✓	No slag.✓
  No additional shielding gas cylinder needed.✓	Need additional cylinder for the shielding gas.✓
  Lower maintenance cost.✓	High maintenance cost.✓

  (Any 6) (6)

[35]

QUESTION 5: TOOLS, IMPLEMENTS AND EQUIPMENT

5.1

5.1.1 Identification of the component in the sketch that serves as a connection between the parts.

Universal joint.✓ (1)

5.1.2 The substance that is used to lubricate the universal joint.

Grease.✓ (1)

5.1.3 ONE application of the universal joint.

• Drive shaft.✓
• Power take off shaft.✓
• Steering mechanism.✓
  (Any 1) (1)

5.1.4 bTWO mechanisms installed in the drive system of a four-wheel drive vehicle that allows disconnection of drive to the front wheels and ONE advantage of each device.

• 4 x 4 Gearbox.✓ 4 x 4 can be disengaged when driving on tar roads.✓
• Front wheel hub locking devices.✓ Wear is reduced on the front wheels and front wheel system.✓
  (4)

5.2 Type of hydraulic cylinder used to lift or lower the fork of the baling machine.

• Double action hydraulic cylinder.✓ (1)

5.3 Function of the lining on the friction plate of a clutch.

• Prevents the pressure plate from slipping.✓
• Heat resistant/Wear resistant.✓
  (Any 1) (1)

5.4 TWO advantages of the diff lock as found on a 4x4 tractor.

• Provide increased traction/torque.✓
• Both wheels turn together regardless of traction available to each.✓
• Each wheel applies rotational force independent of the available traction.✓
  (Any 2) (2)

5.5 ONE advantage of a bearing without a grease nipple.

• Comes lubricated from manufacturer.✓
• No additional greasing needed.✓
• Sealed bearing.✓
  (Any 1) (1)

5.6

5.6.1 Calculation of the pulley ratio of the electrical motor to the pump.

Driven pulley
Drive pulley

= 450mm✓  
    150mm✓
= 3✓
Ratio: 3:1✓
(3)

5.6.2 bFOUR reasons for using a V-belt instead of a flat belt.

• V-belts do not slip off pulleys.✓
• V-belts draw tighter around a pulley when tension increases.✓
• Lubrication is never necessary.✓
• V-belts are relatively strong, and under normal circumstances do not easily break.✓
• V-belts last longer than flat belts.✓
• Cold, moist conditions, age or use do not cause V-belts to stretch or shrink.✓
  (Any 4) (4)

5.6.3 Part that allows relative rotation to the rotor shaft.

• Bearing.✓ (1)

5.7 FOUR possible faults in the engine that can cause the presence of oil in the combustion chamber.

• Piston rings are worn.✓
• Cylinder gasket blown.✓
• Crack in cylinder head.✓
• Cylinder sleeves/walls are worn.✓
• Valve stem seals perished/worn.✓
  (Any 4) (4)

5.8 Properties of a functional clutch.

• It should engage smoothly and not jam, slip or shudder.✓
• It should be capable of transferring the maximum load of the engine without slip.✓
• When the clutch is disengaged, it should do so completely and not tend to drag.✓
• The clutch should be of such a nature that it could be engaged or disengaged comfortably by hand or foot.✓
• The friction material used on the clutch plate should not only be highly wear and temperature resistant.✓
  (5)

5.9 FOUR parts that must be examined on a second hand tractor before you decide to buy it.

• Engine.✓
• Gearbox.✓
• Final drive.✓
• Cooling system.✓
• Fuel system.✓
• Steering mechanism.✓
• Instruments.✓
• Battery.✓
  (Any 4) (4)

5.10 Function of the parts of a hammer mill.

5.10.1  The hopper: Facilitates the process of feeding.✓  (1)
5.10.2  Cyclone: Separates the grounded material from the air.✓  (1)

5.11  Reason for the wheels of a front-end loader to be set at its widest position.

• To increase stability.✓ (1)

5.12 Servicing procedure when preparing a combine harvester for the harvesting season.

• Lubricate/Grease all moving parts.✓
• Correct tension of belts and chains.✓
• Check that all parts are functioning by operating it slowly.✓
• Replace all worn parts.✓
• Service according to manufacturer's specifications.✓
• Lift up all dust release guards.✓
• Check that no blades are damaged and are sharp.✓
  (Any 4) (4)

[40]

QUESTION 6: WATER MANAGEMENT

6.1 FOUR factors to be considered before deciding on a relevant irrigation method.

• Type of crop that must be irrigated.✓
• Determine the amount of water that is available.✓
• Type of irrigation system.✓
• Type of pump.✓
• Determine the water flow (LPM) and pressure requirements.✓
• Size of the field.✓
• Create the first irrigation design.✓
  (Any 4) (4)

6.2 Goals of irrigation scheduling.

• To apply adequate water to the root zone of the plant.✓
• Prevent overwatering.✓
• Allow the soil to dry out in between watering.✓
• To allow air to enter the soil.✓
  (Any 3) (3)

6.3 TWO structural problems that can influence the sprinkler.

• The springs can lose tension or break.✓
• The nozzles can be blocked.✓
• The water pressure is inadequate.✓
  (Any 2) (2)

6.4 A device that a farmer can use to measure the evaporation tempo in a maize field.

• Evaporation pan/Class A evaporation pan.✓ (1)

6.5 Labelled drawing of a French water drainage system.
Marks will be allocated for:

(6)
6.6 FIVE items that should never be disposed off in a septic tank.

• Cigarette butts.✓
• Sanitary pads/towels. ✓
• Detergents.✓
• Fats and oils.✓
• Laundry waste.✓
• Plastics. ✓
  (Any 5) (5)

6.7 THREE reasons to determine the flow rate in a pipe delivery system.

• For correct calibrating of the sprayers.✓
• For effective scheduling of irrigation.✓
• To prevent the over utilisation of the water source.✓
  (3)

6.8

6.8.1 THREE advantages of a centre pivot irrigation system.

• No labourer needed to shift the pipes/system.✓
• One-man operation.✓
• Automated watering system/scheduling.✓
• Pesticides/fertilizers are applied through the system.✓
  (Any 3) (3)

6.8.2 THREE design principles that are built into the centre pivot irrigation system to ensure uniform distribution of water.

• Distribution pattern of the sprayers.✓
• Nozzle opening diameter must increase proportionally further from the centre to allow for a higher water application.✓
• Spacing between sprayers must decrease proportionally further from the centre.✓ (3)

[30]

TOTAL SECTION B: 160
GRAND TOTAL: 200