WAEC SSCE - Agricultural Science - 2020 (Practical)
Pregunta 1 Informe
(a) Give three reasons for stocking K (TILAPIA) and L (CATFISH) together in a pond.
(b) List four fishing gears used for harvesting specimens K and L in a pond.
(c) Name four products that could be made from specimen M(MILK).
(d) State four reasons for adding specimen N (LIME) to the pond in which specimens K and L are stocked.
(a) Three reasons for stocking specimen K (tilapia) and specimen L (catfish) together in a pond
- They have different feeding habits and occupy different feeding zones. Tilapia is a herbivorous surface feeder while catfish is a carnivorous bottom feeder, so the food and space in the pond are fully utilised.
- The catfish preys on and controls the population of tilapia, which breeds rapidly and would otherwise overpopulate and become stunted in the pond.
- Stocking the two together increases total fish yield and maximises the farmer's income per unit area of pond.
(b) Four fishing gears used for harvesting specimens K and L
- Hook and line.
- Fish trap/basket.
- Cast net (or seine net, drag net, scoop net).
- Fishing spear/harpoon.
(c) Four products that could be made from specimen M (milk)
- Cheese.
- Yoghurt.
- Butter.
- Ice cream (skimmed/condensed milk, casein, ghee and whey are also obtained).
(d) Four reasons for adding specimen N (lime) to the pond
- It neutralises acidity and corrects the pH of the pond water and mud.
- It reduces turbidity, causing suspended particles to settle so that the water becomes clearer.
- It supplies calcium for the bone development of the fish and destroys leeches and other parasites on the fish.
- It increases the availability of nutrients such as phosphorus and encourages the growth of plankton (natural fish food).
Detalles de la respuesta
(a) Three reasons for stocking specimen K (tilapia) and specimen L (catfish) together in a pond
- They have different feeding habits and occupy different feeding zones. Tilapia is a herbivorous surface feeder while catfish is a carnivorous bottom feeder, so the food and space in the pond are fully utilised.
- The catfish preys on and controls the population of tilapia, which breeds rapidly and would otherwise overpopulate and become stunted in the pond.
- Stocking the two together increases total fish yield and maximises the farmer's income per unit area of pond.
(b) Four fishing gears used for harvesting specimens K and L
- Hook and line.
- Fish trap/basket.
- Cast net (or seine net, drag net, scoop net).
- Fishing spear/harpoon.
(c) Four products that could be made from specimen M (milk)
- Cheese.
- Yoghurt.
- Butter.
- Ice cream (skimmed/condensed milk, casein, ghee and whey are also obtained).
(d) Four reasons for adding specimen N (lime) to the pond
- It neutralises acidity and corrects the pH of the pond water and mud.
- It reduces turbidity, causing suspended particles to settle so that the water becomes clearer.
- It supplies calcium for the bone development of the fish and destroys leeches and other parasites on the fish.
- It increases the availability of nutrients such as phosphorus and encourages the growth of plankton (natural fish food).
Pregunta 2 Informe
(a) What is the aim of the experimental set-up F?
(b) List three materials that could be used in carrying out the experiment in the set-up F.
(c) Outline three steps invo?ved in carrying out the experiment.
(d) Name four soil components observed in the experimental set-up.
(e) Draw and label the experimental set-up.
(a) Aim of experimental set-up F
To determine the texture of a soil sample by sedimentation, that is, by separating its particles into layers according to particle size.
(b) Materials for the experiment
- Soil sample
- Measuring cylinder or transparent glass jar
- Water
Other suitable materials include a glass rod or stirrer and hydrogen peroxide or Calgon.
(c) Steps involved
- Put a quantity of the soil sample into a measuring cylinder.
- Add water and a little hydrogen peroxide or Calgon, then stir thoroughly with a glass rod or shake vigorously to disperse the soil particles.
- Allow the mixture to stand undisturbed for some hours until the particles settle in distinct layers.
(d) Four soil components observed
Coarse sand, fine sand, silt and clay. Organic matter may also be seen floating on the water surface.
(e) Labelled drawing of the experimental set-up
The largest and heaviest particles settle first at the bottom, while the finest particles settle near the top.
Detalles de la respuesta
(a) Aim of experimental set-up F
To determine the texture of a soil sample by sedimentation, that is, by separating its particles into layers according to particle size.
(b) Materials for the experiment
- Soil sample
- Measuring cylinder or transparent glass jar
- Water
Other suitable materials include a glass rod or stirrer and hydrogen peroxide or Calgon.
(c) Steps involved
- Put a quantity of the soil sample into a measuring cylinder.
- Add water and a little hydrogen peroxide or Calgon, then stir thoroughly with a glass rod or shake vigorously to disperse the soil particles.
- Allow the mixture to stand undisturbed for some hours until the particles settle in distinct layers.
(d) Four soil components observed
Coarse sand, fine sand, silt and clay. Organic matter may also be seen floating on the water surface.
(e) Labelled drawing of the experimental set-up
The largest and heaviest particles settle first at the bottom, while the finest particles settle near the top.
Pregunta 3 Informe
(a) State two uses each of specimens A (HOE) and B(PICK AXE)
(b) Name four crops that require the use of specimen D (BUDDING KNIFE) during propagation.
(c) Name three other tools that could serve the same purpose as specimen E (BURDIZZO).
(d) Mention four ways of maintaining specimen A (HOE) on the farm.
(a) Two uses each of specimens A and B
Specimen A (hoe):
- Making ridges, heaps, mounds and seedbeds.
- Weeding and loosening or tilling the topsoil.
Specimen B (pick axe):
- Breaking up hard, compact or stony ground.
- Digging holes and pits and uprooting tree stumps, roots and stones.
(b) Four crops that require specimen D (budding knife) during propagation
- Citrus (orange).
- Mango.
- Cocoa.
- Rubber (cashew and avocado are also budded).
(c) Three other tools that serve the same purpose as specimen E (Burdizzo)
Specimen E is a bloodless castrating instrument, so other tools used to castrate livestock are:
- Elastrator (rubber-ring applicator).
- Emasculator.
- Castrating knife or scalpel.
(d) Four ways of maintaining specimen A (hoe) on the farm
- Wash off soil and dry the hoe after every use.
- Sharpen the blunt cutting edge regularly.
- Oil or grease the metal blade to prevent rusting.
- Store in a cool, dry tool shed and tighten or replace a loose or termite-damaged handle.
Detalles de la respuesta
(a) Two uses each of specimens A and B
Specimen A (hoe):
- Making ridges, heaps, mounds and seedbeds.
- Weeding and loosening or tilling the topsoil.
Specimen B (pick axe):
- Breaking up hard, compact or stony ground.
- Digging holes and pits and uprooting tree stumps, roots and stones.
(b) Four crops that require specimen D (budding knife) during propagation
- Citrus (orange).
- Mango.
- Cocoa.
- Rubber (cashew and avocado are also budded).
(c) Three other tools that serve the same purpose as specimen E (Burdizzo)
Specimen E is a bloodless castrating instrument, so other tools used to castrate livestock are:
- Elastrator (rubber-ring applicator).
- Emasculator.
- Castrating knife or scalpel.
(d) Four ways of maintaining specimen A (hoe) on the farm
- Wash off soil and dry the hoe after every use.
- Sharpen the blunt cutting edge regularly.
- Oil or grease the metal blade to prevent rusting.
- Store in a cool, dry tool shed and tighten or replace a loose or termite-damaged handle.
Pregunta 4 Informe
(a)(i) Name the toxic substance found in specimen G (FRESH CASSAVA TUBER).
(ii) Suggest four ways of removing the toxic substance named in (a)(i).
(b) State two uses each of specimens I (ONION BULBS) and J (PEPPER FRUITS).
(c) List four pests of specimen I.
(d) Name two groups of crops to which specimens I and J belong based on their uses.
(a)(i) Toxic substance in specimen G (fresh cassava tuber)
The toxic substance is hydrocyanic acid (prussic acid / hydrogen cyanide), derived from a cyanogenic glycoside.
(a)(ii) Four ways of removing the toxic substance
- Grating the tubers and squeezing out the juice under pressure.
- Soaking (steeping) the tubers in water for some days to ferment.
- Boiling or cooking the tubers thoroughly.
- Sun-drying or frying the grated mash.
(b) Two uses each of specimens I and J
Specimen I (onion bulbs):
- Used for flavouring food and eaten as a vegetable.
- Used medicinally and as a source of vitamins A and C.
Specimen J (pepper fruits):
- Used as a spice or condiment to flavour food.
- Used medicinally and as an insect repellant in stored produce.
(c) Four pests of specimen I (onion)
- Thrips.
- Onion maggot (onion fly).
- Nematodes (eelworm).
- Rodents.
(d) Two groups of crops to which specimens I and J belong (based on use)
- Vegetable crops.
- Spice (condiment) crops.
Detalles de la respuesta
(a)(i) Toxic substance in specimen G (fresh cassava tuber)
The toxic substance is hydrocyanic acid (prussic acid / hydrogen cyanide), derived from a cyanogenic glycoside.
(a)(ii) Four ways of removing the toxic substance
- Grating the tubers and squeezing out the juice under pressure.
- Soaking (steeping) the tubers in water for some days to ferment.
- Boiling or cooking the tubers thoroughly.
- Sun-drying or frying the grated mash.
(b) Two uses each of specimens I and J
Specimen I (onion bulbs):
- Used for flavouring food and eaten as a vegetable.
- Used medicinally and as a source of vitamins A and C.
Specimen J (pepper fruits):
- Used as a spice or condiment to flavour food.
- Used medicinally and as an insect repellant in stored produce.
(c) Four pests of specimen I (onion)
- Thrips.
- Onion maggot (onion fly).
- Nematodes (eelworm).
- Rodents.
(d) Two groups of crops to which specimens I and J belong (based on use)
- Vegetable crops.
- Spice (condiment) crops.
