AGRIC SCIENCE ESSAY QUESTIONS 2015

Hint

(i)        It detennines the degree of coarseness of fineness of a soil sample

(ii)        It determines the types of crops to be cultivated or grown in a farmland

(iii)       It is the most consistent physical property of soil

(iv)       The proportion of the different fractions determined the type of soil.

(v)        Soil texture can reveal the different types of soil particles e.g. sand, fine sand, coarse sand, silt and clay.

Hint

(i)        it prevents soil erosion and evaporation by tightly binding soil particles.

(ii)        Organic matter is a rich source of plant nutrient

(iii)       It brings about an increase in the number of important soil microrganisms such as bacteria, fungi e.t.c

(iv)       It helps to improve the water-holding capacity of soil

(v)        it helps to moderate soil temperature in order to allow good plant development.

Hint

(i)        They produce very many seeds.

(ii)        Their seeds have long period of dormancy

(iii)       They .survive all types of soil conditions

(iv)       They are resistant to trampling

(v)        They are highly viable and have short life-cycle

Hint

Cultural methods, biological method and chemical method.

Cultural methods: It involves all the cultivation practices such as crop rotation, hoeing, hand pulling, thinning, flood mowing e.t.c to control weeds.

 Biological method: It involves the use of animals that are mostly grazers to feeds on the weeds. However care must be taken in the kind of animal introduced.

Hint

nitrogen cycle

Hint

Ammonificaiton or mineralization is the conversion of organic nitrogen to ammonia by bacteria.

Nitrification is the conversion of ammonia or ammonium compounds to nitrites and then to nitrates.

Hint

plant cell

Hint

(i) Plastids: There are different finds of plastids in plant cells which include                                   (b)chloroplasts:- It cantinas chlorophyll which traps sunlight for photosynthesis

• leucoplast:- for the storage of starch
• chloroplasts:- For colouration

(3) Mitochondrion:- it is the power house of a cell and it is known to be the site of aerobic respiration

(ii) Lysosome:- it destroys bacteria in the plant cell.

Hint

(i) Acidic rainfall

(ii) Presence of sulphur in the soil sulphur undergoes oxidation and dissolution to form weak acid the soil

(iii) Through leaching

(iv) excessive fertilizer application

(v) nutrient up take by plants which are later harvested

Hint

(i) it reduces the formation of pods in legumes

(ii) It causes nutrient deficiency especially calcium, phosphorus and nitrogen

(iii) It dictates crops grown on the soil

(iv) It helps in the distribution of crops in a farmland.

Hint

1. It neutralizes or reduces soil acidity

(ii) It improves soil structure

(iii) It Release calcium ions to plants

(iv) It helps in improving the nutrient status of the soil

(v) It increases the activities of soil micro organisms

Hint

A nursery is a place where plants are propagated and grown to usable size.

Hint

(1) Nurseries may supply plants for gardens, for agriculture for forestry and for conserving biology.

(ii) It is convenient to look after the baby seedlings

(iii) It eliminates the problem  of difficult soil

(iv) easy weed control

(v) more optimal use of hybrid seeds higher yields.

Hint

Hint

A seed is a fertilized ovule

Hint

1. Breeder seed: This is the progeny of nucleus seeds multiplied in large area as per indent of Department of Agriculture and cooperation (DOAC), Ministry of Agriculture under supervision of plant breeder.
2. Foundation seed: It is the progeny of breeder seed produced by recognised seed producing agencies in. public and private sectorunder supervision of seed certification agencies in a such a way that its quality is maintained according prescribed filed seed standards.

iii.        Certified seed: This is the progeny of foundation seed produced by registered seed growers under supervision of seed produced by registered seed growers under supervision of seed certification agencies to maintain the seed quality as per minimum seed certification standards.

1. Nuclear seed: This is the 100% genetically pure seed with physical purity and produced by original breeders.

Hint

The purpose of seed certification is to maintain and make available to the public, through certification, high quality seeds and propagating materials of notified kind and varieties so grown and distributed as to ensure genetic identity and genetic purity

Hint

Origin: The history of modem-day maize begins the dawn of human agriculture, about 10,000 years ago Ancient farmers in what is now mexico took the first steps in domesticating maize when they simply chose which kernels (seeds) to plan. These farmers no noticed that not all plants were the same.

Methods of propagation: It is propagated by seeds

Climatic requirement: It requires   a temperature   of about 20°C- 30°C, rainfall should be between 75cm-l 50cm per annum.

Soil requirement: Well drained loan and silt loam with fine tilth.

Land Preparation: (i) clearing of land

(ii)       stumping should be done

(iii)      land should be harrowed

‘iv)      Ridges can also be prepared.

Planting: Early maize is planted between march and April while late maize is planted between July and August or exactly in August. Also, maize can be planted anytime depending on the rate of rainfall in the north and south.

Hint

i. Chlorotic areas appear on infected plants leaves parallel to the veins of the leaf.

ii. This retards plant development.