WAEC SSCE - Agricultural Science - 2018 (Practical)

Antwortdetails

(a) Three farm animal hosts of Specimen O (Tick)

• Cattle
• Sheep
• Goat (dogs and horses are also hosts)

(b) Four damages done by each specimen on their hosts

Specimen N (Liver fluke)

• It destroys liver tissue, causing liver rot (fascioliasis).
• It causes anaemia by feeding on blood and liver cells.
• It leads to loss of weight and emaciation.
• It lowers productivity (meat and milk) and can cause death in heavy infestation; the liver is condemned at slaughter.

Specimen O (Tick)

• It sucks blood, causing anaemia and weakness.
• It transmits diseases such as redwater (babesiosis), heartwater and anaplasmosis.
• Its bites create wounds that admit secondary infection and attract flies (myiasis).
• It causes irritation and restlessness that reduce feeding and productivity, and it damages the hide.

(c) Four ways of controlling Specimen O (Tick)

• Dip or spray the animals regularly with an acaricide.
• Hand-pick and destroy the ticks on the animals.
• Practise rotational grazing to break the tick's life cycle.
• Clear bushes around the pasture and quarantine and treat newly introduced animals.

Antwortdetails

(a) Organism that caused the damage on each specimen

• Specimen J: Maize weevil (Sitophilus zeamais).
• Specimen K: Yam beetle.
• Specimen L: Cassava mosaic virus.
• Specimen M: Fruit rot fungus (of tomato).

(b) Three ways the maize weevil (Specimen J) is of economic importance

1. It destroys stored maize, causing food loss and food shortage.
2. It destroys seed viability and reduces seed germination.
3. It reduces the market value and quantity of produce, lowering income and raising the cost of production through control measures.

(c) Two ways of controlling each organism

Maize weevil:

• Store the grain in air-tight containers.
• Treat the grain with an appropriate insecticide or store-protectant dust.

Yam beetle:

• Treat the yam setts with an appropriate insecticide before planting.
• Practise crop rotation.

Cassava mosaic virus:

• Plant resistant varieties and clean, disease-free stem cuttings.
• Uproot and burn infected plants and maintain farm sanitation.

Fruit rot fungus:

• Grow resistant varieties and remove infected plants.
• Stake the tomato plants and treat the soil with a copper-based fungicide.

Antwortdetails

(a) Three uses of each specimen

A (Axe)

• Felling of trees during land clearing.
• Splitting and cutting of logs and firewood.
• Removing tree branches and cutting through thick stumps.

B (Spade)

• Digging of soil and making of planting holes.
• Making ridges, beds and drainage channels.
• Mixing and turning of manure, compost or concrete.

D (Hand trowel)

• Transplanting seedlings from the nursery.
• Making small holes for planting seeds or seedlings.
• Lifting and potting nursery plants and light weeding in beds.

F (Hand fork)

• Loosening and aerating the soil around growing plants.
• Weeding between plants in a bed.
• Mixing manure or fertilizer into the topsoil.

(b) Three ways of maintaining Specimen A (Axe)

• Clean and dry the metal blade after use to prevent rusting.
• Sharpen the cutting edge regularly to keep it effective; oil or grease the metal part.
• Keep the handle firm (replace if loose or cracked) and store the axe in a dry place.

Antwortdetails

(a) Classification of the specimens using litmus paper and water

• G (Neutral soil): Neither red nor blue litmus paper changes colour.
• H (Acidic soil): Turns blue litmus paper red.
• I (Alkaline / basic soil): Turns red litmus paper blue.

(b) Steps in classifying the specimens

1. Place a small portion of each soil sample (G, H and I) into separate clean containers.
2. Add distilled water to each and stir to make a soil suspension or paste.
3. Allow the mixture to settle for a few minutes.
4. Dip a strip of red litmus paper and a strip of blue litmus paper into each suspension.
5. Observe and record the colour change: no change means neutral (G); blue turning red means acidic (H); red turning blue means alkaline (I).

(c)

(i) A pH value of 4.5 indicates that the soil is acidic (strongly acidic).

(ii) Three effects of acidity on crop production

• It reduces the availability of essential nutrients such as nitrogen, phosphorus and potassium.
• It causes toxicity of aluminium, iron and manganese to plant roots.
• It lowers the activity of soil micro-organisms and poor nodulation in legumes, leading to stunted growth and low yield.

(iii) Three factors that could cause acidity

• Leaching of basic cations by heavy rainfall.
• Use of acid-forming fertilizers such as ammonium sulphate.
• Decomposition of organic matter releasing organic acids.