WAEC Agricultural Science Specimen 2018 Answers Expo
Read below for Agricultural Science Specimen 2018 Expo for WAEC
Question 1
(a) Distinguish between the following agricultural systems:
(i) mono culture and monocropping;
(ii) shifting cultivation and land rotation. [ 6 marks]
(b) State four problems of commercial agriculture in West Africa. [4 marks]
(c) Mention four uses of the farm tractor. [4 marks]
OBSERVATION: This question was fairly attempted by the candidates. In question la (i and ii), majority of the candidates were unable to distinguish between some agricultural systems (i.e monoculture and monocropping; shifting cultivation and land rotation). However, in question 1 (b), most candidates were able to state the problems of commercial agriculture in West Africa. Further to this, majority of the candidates were able to mention the uses of the farm tractor and list indigenous methods of land preparation as demanded in questions 1 (c) and (d).
The expected answers include:
Distinction between agricultural systems:
Monoculture is the practice of cultivating one and the same crop on the same piece of land
every cropping season.
Whereas,
Monocropping is a practice of cultivating a single crop species each growing season and
harvesting it before another crop is planted.
Shifting cultivation is a fanning system whereby a piece of land is cultivated continuously for some years and then abandoned as a result of the decline in soil fertility, build-up of pests and diseases,and the resultant reduction in crop yield. The farmer abandons not only the exhausted farmland but also his settlement for a new fann and a new settlement with no hope of coming back.
Whereas
Land rotation involves growing crops on a piece of land until it is exhausted and the land is left to follow for some years before it is used again. The farmer clears other areas in succession to make new farms while remaining in his farmstead.
Question 2
(a) Explain briefly how the following affect agricultural production:
(i) agricultural education and extension;
(ii) environmental degradation.[ 8 marks]
(b) Enumerate three problems associated with communal land tenure system. [3 marks]
(c)List four components of an incubator. [2 marks]
(d) Mention one storage structure for each of the following farm produce:
(i) yam tubers;
(ii) cowpea seeds;
(iii) fresh fish. [ 3 marks]
OBSERVATION: Few candidates attempted this question. In question 2(a) (i & ii), many candidates could not explain how agricultural education and extension, and environmental degradation affect agricultural production. However, in question 2(b), most candidates were able to enumerate the problems associated with communal land tenure system. In question 2(c), majority of the candidates could list the components of an incubator. In addition to this, majority of the candidates were able to mention the storage structure for farm produce (i.e. yam tubers; cowpea seeds and fresh fish) as requested in question 2(d)(i - iii).
The expected answers include:
How agricultural production is affected by
Agricultural education and extension
Improved/better farm management decision making
Improve procurement of farm inputs
Access to marketing information and strategy
Keeping of accurate farm records
Acquisition of loans and their utilization
Improve the farmers social disposition
Help the fanners to understand and adopt modem farming techniques for improved productivity
Agricultural education motivates the youths to take up farming as a profession
Relay farmers' problems to the government ministries, research institutes and universities
Carry information from government ministries, universities and research institutes to fanners.
Environmental degradation:
Desert encroachment exposes the soil to erosion
Erosion renders the soil unproductive and unsuitable for agriculture
Oil spillage pollutes the fishing and drinking water and kills all the aquatic life thus reducing the profit of the fishermen
Drinking water for the farm family and their animals is polluted; thus exposing them to health risks
Air pollution by toxic fumes from industrial gases reduces the quality of air available to the
farm family and their animals•
Aid rains from air pollution cause soil acidity and destruction of crops
Deforestation exposes the soil to erosion agents
Overgrazing causes erosion and hard pans
Bush burning damages the physical structure of the soil and reduces soil fertility
Air pollution reduces photosynthesis and thus reduces yield
Plant population for livestock consumption is not much
Question 3
(a) Explain the term chemical weathering of rocks. [2 marks]
(b) Discuss four processes of chemical weathering of rocks. [ 10 marks]
( c) State four ways in which soil temperature is important for crop growth. [ 4 marks ]
OBSERVATION: This question was poorly attempted by the candidates. In question 3(a), majority of the candidates could not explain chemical weathering of rocks. Also, in question 3(b), many candidates were unable to discuss the processes of chemical weathering of rocks. Further to this, most candidates could not state ways in which soil temperature is important for crop growth.
The expected answers include:
Explanation of chemical weathering of rocks:
Chemical weathering is the decomposition of rocks by chemical agents formed through the reaction of water with atmospheric gases such as air (oxygen and carbon dioxide) As some minerals in the rocks are dissolved and others change into new chemical products therefore disintegration of rocks occurs.
Discussion of chemical weathering of rocks (Any four)
Hydration
Occurs when water combines with or binds to some minerals Intact water may bind to silicates, oxides of iron
Hydrated compounds are soft and easily fragmented It does not usually affect the chemical composition of the hydrated product
Example of hydration reaction are
Fe203 + 3H20 
. Fe203.3H20
. Fe203.3H20
Haematite Limonite/Hydrated Haematite (Yellow)
(Red)
OR
CaSO4 + 2H20 CaSO4 .2H20
CaSO4 .2H20
(Calcium Sulphate) (Gypsum)
OR
CuS04 + 5H20 CuS04. 5H20
CuS04. 5H20
(Anhydrous Copper Sulphate) Carbonation (Hydrated Copper II sulphate )/Blue stone/
Carbonation
This is brought about by the combination of carbonate (C02-3) or bicarbonte (HCO-3) ions with rock minerals
The carbon dioxide released to the atmosphere from various sources combines with water/rainwater to form carbonic acid
C02 + H20 
H2C03
H2C03
The carbonic acid attacks the minerals and C02 in the rock.
In limestone or marbles the calcite present is dissolved.
Oxidation/Reduction
Atmospheric oxygen and free oxygen in rain water carry out this reaction
Minerals containing iron (Ferrous form), manganese and sulphur are the ones most frequently affected by this reaction
When they are exposed to air and water, the ferrous ion is oxidized to the ferric Fe2 + state.
The change in valency from Fe ++ to Fe + destabilizes the molecule and leads to disintegration
4Fe C03 + 02 2Fe203 + 4C02
+ 4C02
Iron (II) Oxygen Iron Oxide Carbon dioxide
carbonate
Hydrolysis
A decomposition reaction in which silicate minerals are broken down Water molecule is split into H+ and OR ions
The H+ replaces the cation from the mineral structure while the mineral is released for plant uptake
Example:
CaSi03 + 2H20H2Si03 + Ca(OH)2
+ Ca(OH)2
Calcium silicate water silica (Calcium Hydroxide)
KAISi30g + H20 Hydrolysis HAISbOg + K+ + OH-
(Microcline) (water) Acid Silicate
Acid Silicate
Hydrolysis is the breaking of the chemical bond in the mineral by water Solution Water can dissolve any soluble mineral present in rocks and carry them from the place of reaction if the land is sloppy
If the land is not sloppy, the products of the soil solution accumulate in that place and form particular types of soil.
Example
Stalactite and stalagmite
Soil temperature
It determines the rate of formation and decomposition of soil organic matter
Low temperature causes a decrease in metabolic activities and reduction in enzymatic reactions in plants
Extreme temperatures will impede the activities of micro-organisms
It affects the level of soil moisture
It affects the absorption of water and nutrients by roots
Optimum temperature promotes seed germination
Appropriate temperature facilitates root development
It determines the population of soil microbes
It determines maturity and ripening of fruits
High temperature causes the wilting of crops
High temperature leads to loss of soil nutrients through volatilization
Optimum temperature promotes the activities of soil microorganisms
High temperature may be harmful to crops by causing premature dropping of fruits
Question 4
(a) Give two reasons for each of the following practices undertaken by some West African farmers.
(i) movement of herdsmen and their flocks southwards to the rain forest zone during the dry season. [ 4 marks]
(ii) preference for the use of simple farm tools over farm machinery. [ 4 marks]
(b) (i) identify four problems associated with the movement of herdsmen. [4 marks]
(ii) Suggest a solution to each of the problems.[4 marks]
OBSERVATION: This question was not popular with the candidates. In question 4(a)(i & ii), majority of the candidates could not give the reasons for the movement of herdsmen and their flocks southwards to the rain forest zone during the dry season. Similarly, they could not give reasons for the preference for the use of simple farm tools over farm machinery by some West African farmers.
Further to this, many candidates were unable to identify the problems associated with the
movement of herdsmen and suggest solutions to the problems.
The expected answers include:
Reasons for some practices undertaken by some West African farmers:
Movement of herdsmen southwards during the dry season
Abundance of forage in the south but scarcity of forage in the north because of the unequal
rainfall distribution in the dry season
Water scarcity in the north during the dry season forces them to move their animals
southwards in search of water.
Preference for the use of simple farm tools:
High cost of farm machinery/inadequate capital
Low level of technical know-how on how to operate and maintain modem machines
High cost of spare parts
Land tenure system fragments farmlands and this discourages large-scale mechanized farming
Simple farm tools are much more readily available
They are also affordable
Easy to maintain
Easy to use
Spare parts are not readily available
Problems associated with the movement of herdsmen:
Exposes animals to natural hazards
Death of animals due to fatigue of travelling long distance
Movement of animals causes destruction ofthe soil structure (compaction)
New diseases are easily introduced into another area
Indiscriminate mating in the herds leading to the transmission of undesirable traits
Diseases spread easily within the herds
Animals cause damage to cultivated crops along their route
Damage to crops brings about serious conflict/clashes between the herdsmen and the local farmers
It exposes the herdsmen to dangers such as extremes of climatic conditions, wild animals, diseases and armed banditry attacks
New pests are easily introduced into another area
It encourages cattle rustling
Neglect of formal education for the children of herdsmen.
Solution to the problems of the herdsmen movement
Provision of adequate security against theft
Disease/pest resistant animals should be reared
Provision of nomadic schools in strategic locations
Provision of irrigation facilities during the dry season in the north/savannah region to help in the artificial pastures
Establishment of grazing reserves at strategic locations in the north by government/ranching
Preservation of fodder which are in abundance in the south into hay and silage and
transported to the north during the dry season
Provision of cattle tracks/paths for easy passage of herds to prevent destruction of crops along their route
Castration of animals with undesirable traits long before the journey
Payment of compensation for damage caused to crops
Both herdsmen and animals should be vaccinated regularly
Note: Solutions to problems must match the problems.
Question 5
(a) Outline six benefits derived from growing ornamental plants. [6 marks]
(b) State four symptoms of cassava mosaic diseases. [ 4 marks ]
(c) Explain the following terms as used in forest management:
(i) selective exploitation;
(ii) regeneration;
(iii) taungya farming [6 marks]
OBSERVATION: This question was well attempted by the candidates. In question 5(a), majority of the candidates could outline the benefits derived from growing ornamental plants. Also, in question 5(b), most candidates were able to state the symptoms of cassava mosaic disease. In addition to this, many candidates could explain forest management terms such as selective exploitation, regeneration and taungya farming as demanded in question 5( c) (i - iii).
Question 6
(a) State four ways in which weeds are beneficial to the farmer. [ 4 marks]
(b) Classify insect-pests into three groups based on their mode of feeding and give
two examples of each. [9 marks]
(c) State three ways by which pasture can be made available to cattle. [ 3 marks]
OBSERVATION: This question was not popular with the candidates. In question 6(a), many candidates could not state ways in which weeds are beneficial to the farmers. However, in question 6(b), majority of the candidates were able to classify insect-pests into groups based on their mode of feeding and give examples. In question 6 (c), most candidates could not state the ways by which pasture can be made available to cattle.
The expected answers include:
Ways in which weeds are beneficial to the farmer
Weeds help in checking soil erosion
Some weeds are useful as food for humans
Some weeds serve as feed for livestock
Certain weeds have medicinal properties
Weeds can be ploughed into the soil to replenish soil nutrients
Some weeds are used for roofmg, making mats, baskets etc
Weeds can be cut and used as mulch
For compost making
Leguminous weeds harbour bacteria that help to fix atmospheric nitrogen into the soil
Ways by which pasture can be made available to cattle
Prepared as hay for livestock
As silage
Cut and carry as fresh fodder/zero grazing
Animals can be taken out for grazing
Question 7
(a) Define each of the following terms as used in animal health:
(i) pests;
(ii) pathogens;
(iii) vectors;
(iv) parasites.[ 8 marks]
(b) Give one example of an organism described by each of the terms in
above. [4 marks]
( c) State four steps involved in silage making. [4 marks]
OBSERVATION: This question was fairly attempted by the candidates. In question 7 (a)(i - iii), most candidates were able to define terms used in animal health (i.e. pests, pathogens, vectors and parasites). Also, in question 7(b), many candidates could give an example of pests, pathogens, vectors and parasites. However, majority of the candidates were unable to state the steps involved in silage
making as requested in question 7(c).
The expected answers include:
Steps involved in silage making:
Dig the silage pit
Cut the fresh grass/forage before flowering
Wilt for few hours/day
Collect the wilted forage and lay it at the bottom of the pit to a reasonable level
Add ash/urea sprinkled on it
Compress and add another layer of wilted forage, compress and add further ash/urea-fertilizer
- Add more wilted forage, ash/urea and compress until pit is filled
Finally compress and then cover with tarpaulin or plastic polythene sheet
Leave to ferment with minimum of 2 - 4 weeks
Question 8
(a) Name four breeds of chicken used for commercial egg production. [ 4 marks]
(b) State two functions of each of the following components in the diet of farm animals:
(i) water;
(ii) minerals;
(iii) antibiotics;
(iv) protein. [ 8 marks]
(c) Enumerate four advantages of the intensive system of rearing ruminants.{ 4 marks]
OBSERVATION: This question was popular with the candidates. In question 8(a), some candidates could not name the breeds of chicken used for commercial egg production. However, in question 1 (b) (i - iv), majority of the candidates were able to state the functions of water, minerals, antibiotics and protein in the diet of farm animals. Further to this, majority of the candidates could enumerate the advantages of the intensive system of rearing ruminants as demanded in question 8(c).
The expected answers include:
- Breeds of chicken used for commercial egg production
- White leghorn
- Rhode Island Red
- New Hampshire
- Plymouth Rock
- Australorp
- Brown Leghorn
- Light Sussex
- Barred Plymouth Rock
Question 9
(a) State three functions of a farm manager. [3 marks]
(b) Explain the following terms as used in agricultural economics:
(i) appreciation;
(ii) salvage value;
(iii) farm budget;
(iv) farm inventory. [ 8 marks]
(c) State five qualities of a good agricultural extension agent. [ 5 marks]
OBSERVATION: Many candidates attempted this question. In question 9(a), majority of the candidates could state the functions of a farm manager. Also, in question 9(b )(i - iv), many candidates were able to explain terms used in agricultural economics (i.e appreciation, salvage value, farm budget and farm inventory), However, some candidates could not state the qualities of a good agricultural extension agent.
The expected answers include:
Qualities of a good agricultural extension agent
Originality in thought, word and action
He must be a good listener
Must be patient with the people
Must be honest and transparent
Must be able to take steps without being directed
Must be able to organize and implement programmes
Must be able to offer clear judgement in all issues
Must stay clear of local politics
Must know and respect the culture of the people
Must be a good mixer
Good knowledge of the subject matter
Must be able to speak the language of the people
Must be a good communicator
He must be friendly
Exemplary leader
Must be able to solve problems as they arise
Question 10
((a) (i) State the law of diminishing returns. [2 marks]
(ii) Explain the main cause of diminishing returns in agricultural production. [2 marks]
(b) A commercial farmer bought a second hand combine harvester for NI00,000.00 in 1990, and sold if for N 30,000.00 in 2000. For the combine harvester, calculate the
(i) salvage value; [ 1 mark]
(ii) total depreciation; [2 marks]
(iii) annual depreciation. [2 marks]
( c) List seven problems of agricultural extension services in West Africa. [7 marks]
OBSERVATION: This question was fairly attempted. In question 10(a)(i & ii), many candidates were able to state the law of diminishing returns and explain the main cause of diminishing returns in agricultural production. However, majority of the candidates could not calculate the salvage value, total depreciation and annual depreciation of a second hand combine harvester as demanded in question 10(b)(i-iii). In question 1O(c), many candidates were able to list the problems of agricultural extension services in West Africa.
The expected answers include:
Calculation of salvage value, total depreciation and annual depreciation of the combine harvester
Salvage value
+ #30,000.00
Total Depreciation
Cost price - Salvage value
= #100,000.00 = #30,000.00
= #70,000.00
Annual depreciation
= Cost price - Salvage value
Useful life in years
= #100,000.00 - #30,000.00
10 years
= #70,000.00
10 years
= #7,000.00