WAEC SSCE - Agricultural Science - 2005 (Practical)

(a)(i) Classification by mode of formation

• Specimen B: a sedimentary rock (formed by the deposition, compaction and cementation of sediments in layers).
• Specimen D: an igneous rock (formed from cooled, solidified molten magma or lava).

(a)(ii) Two other rocks for each mode of formation

• Sedimentary (like B): limestone and shale.
• Igneous (like D): basalt and gabbro.

(b) Three differences between specimens B and D

(c) Three uses of specimen D (igneous rock) in agriculture

1. Used to control erosion on farmland.
2. Used for building farm structures and constructing farm roads.
3. Used for grinding and sharpening farm tools.

(d) Five disadvantages of an abundance of specimen D on farmland

1. It reduces the amount of arable land available for cropping.
2. It prevents root penetration and disturbs the growth of plants.
3. It makes tillage operations difficult and increases their cost and drudgery.
4. It causes farm implements to wear out quickly.
5. It predisposes man and animals to injury and provides a hideout for reptiles and rodents.

(a) Identification of specimens

• Specimen G: Pepper fruit.
• Specimen H: Onion bulb.
• Specimen I: Cotton seeds.
• Specimen K: Okro.

(b) Two uses of each of specimens G and H

Specimen G (pepper fruit):

1. Used as a spice and preservative for food.
2. Used as an insect repellent in stored foodstuff (and has medicinal uses and serves as an egg-yolk colourant).

Specimen H (onion bulb):

1. A source of vitamins A, B and C.
2. Used for flavouring dishes (and has medicinal uses).

(c) Group of crops to which specimens H, I and K belong

• H (onion): spice crop.
• I (cotton seeds): fibre crop.
• K (okro): vegetable crop.

(d) Planting operations for specimen G (pepper)

1. Clear and plough the land, and prepare nursery beds.
2. Separate the seeds from the fruits and plant them about 1 cm deep in the nursery.
3. While in the nursery, weed, shade and water the seedlings regularly.
4. Transplant to the field after 3 to 5 weeks by removing each seedling with a ball of soil around the roots, doing so in the evening or early morning.
5. When well established, apply fertilizer and insecticides where necessary.

(e) Two pests of specimen H (onion): thrips and cutworms (maggots, crickets and eelworms are also pests of onion).

Specimen F is a knapsack (back-pack) sprayer.

(a) Three other equipment that perform similar functions as specimen F

1. Motorised (power) sprayer.
2. Hand (compression) sprayer.
3. Tractor-mounted or boom sprayer.

(b) Five safety precautions when using specimen F

1. Ensure the sprayer is in good condition and free of leaks before starting.
2. Read and follow the instructions on the chemical container, and mix the chemical at the correct concentration.
3. Wear protective clothing (overall, hand gloves, nose mask, goggles and boots).
4. Spray down-wind, never against the wind, and do not walk into freshly sprayed areas.
5. Do not eat, drink or smoke while spraying, do not clear a blocked nozzle with the mouth, and wash the body thoroughly after use.

(c) How specimen F is used

Pour a measured quantity of water into the tank, add the correct amount of chemical and mix well, then close the tank with its lid. Pump the lever to raise the pressure within the tank, mount the sprayer on the back, and direct the nozzle at the crops while walking steadily away from the sprayed area, pumping occasionally to maintain the pressure. After use, empty, wash and clean the tank.

(d) Three faults that may develop in specimen F when in use

1. Clogging (blockage) of the nozzle by dirt or undissolved chemical.
2. Leakage of chemical from the tank, hose or joints (or a ruptured hose).
3. Loss of pressure from the pressure chamber due to a worn or faulty pump lever/piston.