WAEC SSCE - Agricultural Science - 2004 (Practical)

Antwortdetails

(a) Identification of specimens

• Specimen N: Ascaris (roundworm).
• Specimen O: Tick.
• Specimen Q: Tapeworm.

(b) One host of each specimen

• N (Ascaris): pig (also poultry).
• O (Tick): cattle (also sheep and goats).
• Q (Tapeworm): cattle (also sheep and goats).

(c) Four economic importance (effects) of specimens N and Q on their host

Specimen N (Ascaris):

1. Causes reduced growth rate and loss of appetite in the animal.
2. Causes weakness, unthriftness and loss in weight (emaciation).
3. Damages body tissues during the migration of the young worms.
4. Reduces product yield, and the animal may die from heavy infestation.

Specimen Q (Tapeworm):

1. Causes loss of blood leading to anaemia.
2. Causes loss in weight (emaciation) and reduced growth rate.
3. Reduces milk yield and lowers meat quality.
4. Causes increased feed consumption without a corresponding weight gain, and general unthriftness.

(d) Four control measures for specimen O (tick)

1. Dipping the animals in acaricides.
2. Spraying or dusting the animals with acaricides.
3. Hand-picking the ticks and practising rotational grazing.
4. Burning of infested pastures and introducing predators such as cattle egrets (biological control).

Antwortdetails

(a) Botanical names of the specimens

• I (Common wireweed): Sida acuta
• J (Coat buttons): Tridax procumbens
• K (Giant star grass): Cynodon plectostachyus (also accepted Cynodon nlemfuensis)
• L (Cogongrass / spear grass): Imperata cylindrica

(b) Description of Specimen K (Giant star grass)

• A perennial grass that spreads by creeping stolons (runners) which root at the nodes to form a dense mat.
• It produces erect flowering stems bearing finger-like (digitate) spikes arranged in a star shape at the top, from which its name is derived.
• Leaves are narrow, flat and green; the plant is drought tolerant and propagated vegetatively.
• It is a valuable fodder and pasture grass, palatable to livestock.

(c) Preparing silage from Specimen K

1. Harvest the grass at the flowering stage when it is succulent and nutritious.
2. Chop the herbage into small pieces to aid compaction.
3. Wilt slightly to reduce excess moisture.
4. Fill the chopped grass into a silo (pit or trench) in layers.
5. Compact each layer firmly to expel air and create anaerobic conditions.
6. Add molasses to supply extra carbohydrate for fermentation.
7. Seal the silo air-tight with polythene sheet and soil.
8. Anaerobic bacteria ferment the sugars to lactic acid, which lowers the pH and preserves the material. It matures in about 3 to 6 weeks as silage.

(d) Two methods of controlling Specimen L (cogongrass)

• Repeated deep ploughing and tillage to expose and destroy the underground rhizomes.
• Application of a systemic herbicide such as glyphosate to kill the whole plant including the rhizomes; slashing before flowering and smother-cropping with cover crops are also effective.

Antwortdetails

Read the volume of water collected in each measuring cylinder. Let the volume collected under set-up A be x ml and the volume collected under set-up B be y ml. In each set-up 120 ml of water was poured through the soil.

(a) Volume of water collected

• Set-up A = x ml
• Set-up B = y ml

(b) Volume of water retained

Water retained = water added − water collected.

• Set-up A: \(120 - x\) ml
• Set-up B: \(120 - y\) ml

(c)(i) Percentage of water that percolated

• Set-up A: \(\dfrac{x}{120} \times \dfrac{100}{1}\%\)
• Set-up B: \(\dfrac{y}{120} \times \dfrac{100}{1}\%\)

(c)(ii) Percentage of water retained

• Set-up A: \(\dfrac{120 - x}{120} \times \dfrac{100}{1}\%\)
• Set-up B: \(\dfrac{120 - y}{120} \times \dfrac{100}{1}\%\)

(d) Better soil for crop production

The soil in set-up A is better for crop production. Reasons:

• It contains organic matter, which binds the soil particles and improves the soil structure.
• The organic matter is a source of nutrients for plant growth, and the rate of leaching of nutrients is lower in A than in B.
• It retains water better than B while still having moderate air space, so moisture is available to plant roots for a longer time.

Antwortdetails

(a) Names of the specimens

• Specimen C: Ranging pole.
• Specimen D: Thread / line.
• Specimen F: Nut.
• Specimen G: Fish hook.
• Specimen M: Grass stem (elephant grass stem).

(b) Fishing equipment improvised from the specimens

A hook and line (fishing line).

(c) Four advantages of using the hook and line

1. It is easy to assemble.
2. Its use does not require much expertise.
3. It is cheap to acquire and all its components are easily available.
4. It can be used in all water bodies and has a very low cost of maintenance.

(d) How the equipment is used

1. Fix the thread to the ranging pole, the grass stem, the nut and the hook.
2. Fix a suitable bait to the hook.
3. Determine the fishing depth and adjust the position of the float accordingly.
4. Lower it into the water so that the sinker (nut) drags the hook and bait down to the required depth.
5. Watch the float for an indication of a catch (the float dips or sinks).
6. When a fish is caught, pull it out of the water and remove the fish from the hook.

(e) Five other pieces of equipment that perform a similar function

1. Fish trap
2. Seine net
3. Drag net / trawl
4. Cast net
5. Spear (fish basket is also acceptable)