Correct Answer: D. magnetic compass

Correct Answer: B. mealybug

Correct Answer: A. land fragmentation

Correct Answer: C. rhizome

Explanation

(a) Distinction between field pest and storage pest:

A field pest is any organism which causes damage to crops when still on the field before harvesting whereas, a storage pest is any organism which causes damage to farm produce in storage.

(b) Reasons for early harvesting of maize from the field:

-To minimize/prevent/control pest attack

-To minimize/prevent/control disease outbreak

-To obtain fresh cobs for human consumption

-To avoid bad weather

(c) Description of methods of crop improvement:

(i) lintroduction

- Involves taking a crop from areas where it has been existing to areas where it has not been existing

- This is possible if the environmental conditions in such areas are similar to those of the plant's original home

- Pollen can be collected and shipped to other areas for artificial pollination

- Plants are allowed into most countries only after they t have passed quarantine tests

(ii) Cross breeding

- Involves the transfer of heritable traits from one plant to another of the same species but different varieties through the fusion of their male and female gametes

- It is used to upgrade species of plants which have qualities such as high yield, disease-resistance and heat/drought! wind tolerance

- Pollen grains from plants with desirable qualities can be collected and transferred manually to the stigma of the flower of another plant of the same species which might be lacking in such character, but has its own special trait such as adaptation to a particular environment

- Offspring with the desirable qualities is selected for propagation

(d) Factors that should be considered when selecting a crop variety for a locality

- Resistance to diseases

- Tolerance to pests

- Adaptability to climatic conditions

- Adaptability to soil requirements

- Superior yield

- Superior quality

- Early maturity

-Uniform growth habit

-Cost of production/other factors of production

-Taste of consumers

-Cultural taboos

-Availability of planting materials

-Availability of land

-Ability to smother weeds

Correct Answer: B. presence of tsetseflies

Correct Answer: B. trypanosome

Explanation

(a) Difference between subsistence agriculture and commercial agriculture

Subsistence Agriculture

• Production is mainly for family consumption
• Less capital is required
• Uses family labour/unskilled labour
• Use of local breeds of animals
• Use of local crop varieties
• Hardly use agro-chemicals/Cultural methods are used to control pests and diseases
• Records are rarely kept Use of primitive/local tools
• Poor housing facilities for rearing animals
• Peasant farmers are involved
• Doer not require improved processing facilities
• Does not involve any marketing Uses crude storage facilities
• Yield per unit area is low
• Food crops are produced
• Small area of land is cultivated
• Use of inorganic fertilizers is limited

Commercial Agriculture

• Production is mainly for sale
• Huge amount of capital is required
• Skilled/hired labour is employed
• Use of exotic/improved breeds of animals
• Use of improved crop varieties
• Mostly use agro-chemicals
• Records are kept Mechanized/use of machines
• Modern housing facilities for rearing animals
• Farmers involved may be rich
• Requires improved processing facilities
• Requires organised market Uses modern storage facilities
• Yield per unit area is high
• Cash crops are produced
• Large area of land may be cultivated
• Frequent use of inorganic fertilizers

(b) Advantages and Disadvantages of sources of farm power

(i) Wind :

Advantages

- Running cost is low

- Wind is safe to use

-Wind is a renewable source of energy

- Wind power is environmentally friendly

Disadvantages

-Wind energy converters work only during windy period and as such lie idle during less windy months/ Excessive variation in wind regimes can adversely affect the cost effectiveness of wind energy

-Too weak a wind force cannot be used for any work Success in exploitation of wind energy highly depends

on the specific site

- Wind mills occupy a large portion of land

- Requires high technical expertise

- Initial cost may be high

(ii) Internal Combustion Engine:

Advantages

- It is versatile/can be used for many farm operations

- Efficient source of power

-Not weather dependent

Disadvantages

-A high capital investment is required

- It requires specialized skills in its operation and maintenance

- In developing countries, there is inadequate spare parts for machines

-It contributes to the degradation of the environment/ It Exhaust gases pollute the environment

-Use is subject to to vagaries of fuel shortage

(iii) Electricity

Advantages:

-A very efficient source of farm Power

-it is versatile, with many valued uses

- It is a clean source of power •

-A large amount of energy can be supplied

- It is a fairly reliable source of farm Power

Disadvantages

-High capital outlay to set up

- Very dangerous to operate

- In developing countries, supply cannot be guaranteed at all time

-Needs technical know-how '

-Maintenance cost is high

Correct Answer: A. underground stems

Correct Answer: D. prevent chilling of the young