WAEC SSCE - Agricultural Science - 2011 (Practical)

Maelezo ya Majibu

(a) Major element contained in each specimen

• Specimen A: Potassium.
• Specimen B: Carbon.
• Specimen C: Calcium.

(b) Three uses of specimens A and B

Specimen A (potassium):

1. Used as a fertilizer and as a component of some fertilizer types.
2. Used in correcting soil acidity.
3. Used in the manufacture of soap (and as a scouring powder).

Specimen B (carbon):

1. Used as a source of heat for roasting or drying farm produce.
2. Used for warming brooder and piglet houses.
3. Used for boiling water in the processing of produce such as palm oil.

(c) Three ways specimen C (calcium) is important in agriculture

1. It is used to decrease soil acidity and to increase the availability of soil nutrients when added to the soil.
2. It is used to decrease acidity in fishpond water and to control leeches and liver fluke (by preventing the hatching of water snails) in fish ponds.
3. It improves soil structure and increases the activities of soil organisms; it is also a component of animal feed and reduces turbidity in fish ponds.

(d) Three physical differences between specimens B and C

Maelezo ya Majibu

(a)(i) Field operation performed using specimens G, H, I and J

Farm surveying.

(a)(ii) Three other pieces of equipment that may be added

1. Levelling staff.
2. Dumpy level (or Abney level / theodolite).
3. Prismatic compass (or Gunter's / metric chain, or offset staff).

(a)(iii) One precaution when using specimen J (garden line)

• Do not pull it too hard when taking measurements, so that it does not snap; and tie it firmly to the pole so it stays straight and horizontal for accurate readings.

(b)(i) Two uses of each specimen

(b)(ii) Two structural differences between K and L

(b)(iii) Two problems from leaving specimen L (mattock) on the field after use

1. The metal blade rusts on contact with rain and dew, blunting it and shortening its life.
2. It becomes a hazard: it may injure farm workers, be run over and damaged by farm machinery, be attacked (its wooden handle) by termites, or be stolen.

Maelezo ya Majibu

(a) Identification of the specimens

(b) Pest, disease and control for specimen O (sweet orange)

• Pest: Aphids (they suck sap from the young shoots and leaves and transmit viral diseases). Control: spray with an appropriate insecticide.
• Disease: Gummosis (collar rot), which causes gumming and rotting at the collar of the tree. Control: grow resistant rootstocks, maintain good farm sanitation and well-drained soil, and apply coal tar or a fungicide to the affected part.

(c) Three uses of specimen M (coconut)

1. The white flesh and the coconut water are eaten and drunk as food and refreshment.
2. Vegetable oil is extracted from the dried copra for cooking, soap and creams.
3. The fibrous husk is made into fibre for brushes, ropes and foot mats.

(d) Two methods of preserving specimen N (sweet pepper)

1. Refrigeration (cold storage).
2. Sun-drying (drying / dehydration).

Freeze-drying, pickling and canning are also acceptable methods.

Maelezo ya Majibu

(a) Identification of specimens

• Specimen P: Tapeworm
• Specimen Q: Liver fluke
• Specimen R: Tick

(b) Part of the host where each is found

(c) Three ways specimen P (tapeworm) is adapted to survive in the host

• The head (scolex) bears suckers and hooks for firm attachment to the host's intestinal wall.
• The body is covered with a tough cuticle which resists digestion by the host's enzymes, and it secretes chemicals that protect it from these enzymes.
• It has many segments (proglottids), each with complete male and female reproductive structures allowing self-fertilization and the production of very many eggs, which greatly increases survival.

(d) Three effects of specimen Q (liver fluke) on the host

• It obstructs the flow of bile into the intestine and reduces the digestion of fat.
• It destroys liver tissue, causing liver rot.
• It causes malabsorption of nutrients, leading to emaciation, weakness and death of the host in heavy infestations.

(e) Four diseases transmitted by specimen R (tick)

1. Heart water disease
2. Red water disease (babesiosis)
3. Tick fever
4. Tick paralysis

(f) Four control measures for specimen R (tick)

1. Dipping the animals in acaricide solution.
2. Spraying the animals with acaricides.
3. Hand-picking the ticks off the animals.
4. Rotational grazing / paddocking, together with regular cleaning of pens and controlled burning of pastures.