WAEC SSCE - Agricultural Science - 2001 (Practical)

Maelezo ya Majibu

(a) Classification of specimens by type of mouthparts

• E (grasshopper): biting and chewing mouthparts.
• F (cotton stainer): piercing and sucking mouthparts.
• G (weevil): biting and chewing mouthparts (borne on a snout/rostrum).

(b) Two damages done to crops by each

• E (grasshopper): defoliates plants by eating leaves; destroys young shoots/stems, reducing yield.
• F (cotton stainer): pierces and sucks sap from bolls, staining the cotton lint; transmits fungal disease that lowers quality.
• G (weevil): bores into and eats stored grains/seeds, reducing weight and viability; introduces moulds and contaminates the produce.
• H (termites): attack and destroy roots and stems, ring-barking and killing plants; damage wooden structures and stored materials.

(c) Two control measures of each

G (weevil):

1. Dry grains well and store in clean, air-tight containers.
2. Treat stored produce with recommended insecticides/dusts and maintain store hygiene.

H (termites):

1. Locate and destroy the termite mounds/queen and apply approved insecticides to the soil.
2. Keep the farm clean, remove wood debris and use termite-resistant/treated materials.

Maelezo ya Majibu

(a) One method of propagating each specimen

• I (cassava): by stem cuttings.
• J (yam): by seed yams / yam setts (tubers).
• K (cocoyam): by corms/cormels (or setts).
• L (ginger): by rhizomes (rhizome splits).

(b) Three advantages of staking specimen J (yam)

1. It exposes the leaves to more sunlight for better photosynthesis and higher tuber yield.
2. It keeps the vines off the ground, reducing pest and disease attack and rotting.
3. It makes weeding and other farm operations easier and improves aeration.

(c) Two pests and two diseases of specimen I (cassava)

Pests: cassava mealybug and variegated grasshopper (also green spider mite, rodents).

Diseases: cassava mosaic disease and cassava bacterial blight.

(d) Toxic substance in cassava and one process of reducing it

The toxic substance is hydrocyanic acid (cyanide / prussic acid, from linamarin). It can be reduced by grating and fermenting, followed by pressing/dewatering and thorough drying or roasting (e.g. in garri processing); soaking in water and boiling also reduce it.

(e) Two uses of specimen L (ginger)

1. Used as a spice/flavouring in food and drinks.
2. Used in medicine (herbal remedy) and in making beverages, and for export/income.

Maelezo ya Majibu

(a) Four effects of specimen M (liver fluke) on farm animals

1. It damages and destroys the liver, causing liver rot (fascioliasis).
2. It causes loss of appetite, weakness and progressive loss of weight/condition.
3. It causes anaemia and general ill-health, lowering productivity (milk, meat).
4. Heavy infestation can lead to death of the animal.

(b) Primary and intermediate host of specimen M

• Primary (definitive) host: sheep, cattle or other ruminants (man can also be affected).
• Intermediate host: the (fresh-water) snail.

(c) Three adaptive features of specimen N (tapeworm) for survival in its host

1. It has hooks and suckers (a scolex) for firm attachment to the gut wall.
2. It has a thick, resistant cuticle that protects it from the host's digestive enzymes.
3. It absorbs already-digested food directly through its body surface (no gut needed) and is hermaphroditic with great reproductive capacity.

(d) Three control measures of each

M (liver fluke):

1. Drain/avoid grazing on marshy, waterlogged pastures.
2. Destroy the snail intermediate host (e.g. with molluscicides).
3. Deworm animals regularly with flukicides and quarantine new stock.

N (tapeworm):

1. Deworm animals routinely with anthelmintics.
2. Maintain good sanitation and dispose of dung/faeces properly to break the life cycle.
3. Cook meat thoroughly and inspect meat to avoid re-infection; control the intermediate host.

Maelezo ya Majibu

(a) Three ways specimen A (radio transmitter) enhances farmers' productivity

1. It broadcasts improved farming practices and extension information to many farmers at once.
2. It gives timely weather forecasts and market price information for planning.
3. It provides early warning on pest/disease outbreaks and government agricultural programmes.

(b) Specimen B (Burdizzo plier)

(i) Operation: Castration (bloodless castration) of male farm animals.

(ii) How it is used: The animal is restrained; the spermatic cord of the testicle is located and placed within the jaws of the Burdizzo, which is then closed firmly to crush the cord without breaking the skin, cutting off blood supply to the testes. The process is repeated on the other cord.

(iii) Two maintenance practices: clean and dry it after use and oil the hinge/joint to prevent rust; keep the jaws well aligned and store in a dry place.

(c) Three uses of specimen C (basket)

1. For harvesting and collecting fruits, vegetables and other produce.
2. For conveying/storing farm produce and eggs.
3. For measuring and marketing produce, and for draining/washing produce.

(d) Importance of specimen D (egg candler)

The egg candler is used to examine eggs against a bright light (candling) to detect fertility, check for blood spots, cracks and the size of the air space, so that only good, fertile eggs are set for incubation and bad ones are removed.