THE HUMAN ASPECTS OF RIVERS
In many countries, rivers form the chief highways of commerce and transport. The Yangtze Kiang is navigable up to 1600 km (1000 miles) from its mouth. The Amazon, the world’s greatest river, is navigable...
Monthly Archive: January 2023
RIVER REJUVENATION
The earth’s crust is far from stable and it is not surprising that in the course of a river’s development, parts may be uplifted or depressed, giving rise to certain characteristic features associated with...
MUSCLES
Muscles can be referred to simply as the flesh mostly associated with bones to give shape to the bodies of animals. The flesh may be red in the case of mammals. General...
TRANSPIRATION
Transpiration is the loss of water vapour from different parts of the plant shoot. These parts include the stomata of leaves, the cuticle of both leaves and young stems, and the lenticels on tree...
TYPES OF COASTS
Despite a great variety of coastal features, coastlines may be divided into two basic types. A) Coastlines of submergence: These are due to the sinking of the land or the rise of the sea,...
COASTAL FEATURES OF DEPOSITION
1) Beaches: Sands and gravels loosened from the land are moved by waves to be deposited along the shore as beaches. This is the most dominant form of the constructive work of the sea....
COASTAL FEATURES OF EROSION
1) Capes and bays: On exposed coasts, the continual action of waves on rocks of varying resistance causes the coastline to be eroded irregularly. This is particularly pronounced where hard rocks, e.g. granites and...
THE MECHANISM OF MARINE EROSION
The most powerful agents of marine erosion are waves. Their origin is due to the sweeping of winds over the water surface, which sets a series of undulating swells surging forward. These become higher...
THE ACTION OF WAVES, TIDES AND CURRENTS
The action of the wind passing over a stretch of sea causes waves to develop and when the waves reach the coast they cause erosion or deposition. Wind passing over water sets up turbulences,...
GILLS
Fish and tadpoles are aquatic vertebrates. They possess gills for gaseous exchange. Gills of fish Fish has four gills on each side of the head. Each gill has two rows of soft gill...
ALIMENTARY CANAL OF PLANARIA
Planaria is a free-living, flat, slender and small worm. The digestive tract consists of a ventrally placed mouth, muscular pharynx and intestine. The pharynx can be protruded from the mouth when attacking a prey....
NIGERIA’S TRADE AND COMMERCE
Trade is the selling and buying of goods and services between areas and peoples. Trade can be local, interregional or international. Nigeria is involved in all these types of trade. The term commerce” is...
RIVER REGIMES
The seasonal variation in the volume of water in a river is known as the regime. A knowledge of the regime of a river is important to man in controlling possible floods, storing up...
GREAT CIRCLE ROUTES
Since the earth is spherical in shape, the shortest distance between any two points on the globe lies along its circumference. There are an infinite number of great circles of equal length running around...
GEOTROPISM
This is the response of plant parts to the stimulus of gravity. Plant shoots grow away from gravity of the earth and are said to be negatively geotropic. Roots grow towards gravity and are...
ORGAN OF SIGHT
The eyes are the organs of sight in the higher invertebrates and all vertebrates. They (eyes) are equipped with photo receptors (rods and cones) to detect light. Most of these animals have two eyes....
LOCATION AND POLITICAL DIVISIONS OF AFRICA
Regional Geography Regional geography is usually defined as the study of the ways in which the combinations of environmental and human factors produce territories or regions with distinctive landscapes and cultural attributes. What this...
POWER SOURCES IN AFRICA
Energy/ Power Sources Africa has various sources of energy or power distributed unevenly over Africa. The main sources of power are Hydro-Electricity Power (HEP), coal, mineral oil, thermal power and nuclear power. Africa accounts...
PRIMARY ECONOMIC ACTIVITIES IN AFRICA
Africa’s primary economic activities depend essentially on primary activities, which are associated with the natural resources that abound in the continent. The main primary economic activities are mining, forest exploitation/lumbering, fishing and livestock rearing....
EXCRETION IN PLANTS
There are no special excretory organs or systems in plants. The plants as living things do carry out excretion. Elimination of certain waste takes place through the stomata and lenticels. The main waste products...
OXYGEN DEBT
The oxygen needed to oxidize lactic acid to pyruvic acid and from pyruvic acid to carbon oxide, water and chemical energy is called Oxygen debt. The quick heavy breathing to take in oxygen to...
TRANSLOCATION
Translocation is the transport of manufactured food substances from the leaves to all parts of the plant. The movement is usually described as downwards from the leaves to the roots but it is also...
EXPERIMENTS ON PHOTOSYNTHESIS
The occurrence of photosynthesis in plants can be shown by experiments. The easiest proof that photosynthesis has taken place is to test for the presence of starch in the green leaves. Experiments should be...
INTERNATIONAL ECONOMIC COOPERATION IN AFRICA
There are a number of international organizations in Africa formed with the aim of promoting peace, social integration, economic cooperation and development of member nation states. These include the African Union (AU), Economic Community...
THE TROPICAL MONSOON AND TROPICAL MARINE LANDS
Distribution Some parts of the world experience seasonal winds like land and sea breeze but on a much larger scale. These are the tropical monsoon lands with on-shore wet monsoons in the summer and...
THE EQUATORIAL REGIONS
Distribution The equatorial, hot, wet climate is found between 5° and 10° north and south of the equator. Its greatest extent is found in the lowlands of the Amazon, the Congo, Malaysia and the...
PLANT NUTRITION
Photosynthesisis the process by which carbohydrates or sugars are manufactured in the green parts of the plants containing chlorophyll by combination of carbon (IV) oxide and water with the aid of radiant energy of...
THE ARCTIC OR POLAR CLIMATE
Distribution The polar type of climate and vegetation is found mainly north of the Arctic Circle in the northern hemisphere. The ice caps are confined to Greenland and to the highlands of these high-latitude...
EARTH ENERGY SYSTEM
Insolation The only source of energy for the earth’s atmosphere is the sun which has a surface temperature of more than 5982°C (10 800°F). The energy travels through space for a distance of 150...
PARASITIC NUTRITION
This is a type of nutrition in which one organism obtains food from another organism and during the feeding process one organism is harmed and does not benefit. The organism gaining food, protection and...
LANDFORMS OF GLACIATED LOWLANDS
Landforms of glaciated lowlands are mainly depositional in nature, brought about by both valley glacier and continental ice sheets. The former leave behind the eroded material in only restricted areas. The imprint of ice...
LANDFORMS OF HIGHLAND GLACIATION
Glaciation generally gives rise to erosional features in the highlands and depositional features on the lowlands, though these processes are not not mutually mu exclusive because a glacier plays a combined role of erosion,...
THE ICE AGE
During the earth’s history, there have been many changes in the pattern of climatic regions. The most recent change came about as a result of a fall in temperature over the whole of the...
ALIMENTARY CANAL OF BIRDS
Mouth The mouth has a horny covered tongue to facilitate swallowing of food substances to the oesophagus. There are no teeth. The lower and upper lips have been modified into sharp strong beaks for...
COMPLETE METAMORPHOSIS IN MOSQUITOES
Mating and laying of eggs The adult male and female mate. The female lays fertilized eggs on the surface of a stagnant water. Eggs are laid in partially sunny but shaded places. Female Anopheles...
CLIMATIC EFFECTS OF OCEAN CURRENTS
1) Temperatures: Coastlands with warm currents offshore tend to have mild climates for their latitudes. Coastlands with cold currents off-shore are cooler than they would otherwise be. The effect of a warm current off-shore...
THE CIRCULATION OF THE PACIFIC AND INDIAN OCEAN
The Circulation of the Pacific Ocean The pattern of circulation in the Pacific is similar to that of the Atlantic except in modifications which can be expected from the greater size and the more...
THE CIRCULATION OF THE ATLANTIC OCEAN
Let us now study more closely the circulation of ocean currents in the Atlantic Ocean. We shall begin with the North and South Equatorial Current at the equator. The steady Trade Winds constantly drift...
THE MOVEMENT OF OCEAN CURRENTS
Ocean currents are large masses of surface water that circulate in regular patterns around the oceans, as shown in the world map in Fig. 12.9. Those that flow from equatorial regions polewards have a...
THE TEMPERATURE OF OCEAN WATER
Like land masses, ocean water varies in temperature from place to place both at the surface and at great depths. Since water warms up and cools down much more slowly than the land, the...
CHROMOSOMAL BASIS OF HEREDITY
Within the nucleus of non-dividing cells are strands or string-like structures known as chromosomes. As the cell is about to divide, the chromatids become more visible as strands with bead-like structures on them. These...
SALINITY OF THE OCEAN
Almost every known chemical element can be found in varying proportions in the oceans whose most characteristic feature is their salinity, in contrast to the fresh water of lakes and streams. All sea water...
THE RELIEF OF THE OCEAN
The ocean basins are in many ways similar to the land surface. There are submarine ridges, plateaux, canyons, plains and trenches. A section drawn across an ocean (Fig. 12.4) illustrates the typical submarine relief...
EXPLORING THE OCEANS
The oceans occupy more than 70 per cent or 364 million sq km (140 million square miles) of the earth’s total area of 510 million sq km (197 million square miles). They have tremendous...
EXPERIMENT ON MINERAL DEFICIENCY
Aim: To demonstrate the effects of mineral deficiency on plants. Material required: Nine wide-mouthed glass jars, corks, nine bean seedlings, glass tube, Sach’s or Knop’s complete culture solution (to provide macro-nutrients), black paper...
MOVEMENT
Movement is the ability of living organisms to move from one place to another. Reasons for movement include searching for food, escape from danger, response to stimuli (either positively or negatively) and for the...
WORLD INDUSTRIAL AREAS
Having examined the various factors which contribute to the location of industrial districts, we shall now look at the major industrial regions of the world. It is no surprise that the greatest industrial areas...
DENTITION
Dentition refers to the number, arrangement and conformation of teeth in an organism. Types of Dentition There are two main types of dentition. These are: Homodont dentition: In this type of dentition, the...
MECHANISM OF RESPIRATORY SYSTEM IN LOWER ANIMALS
Unicellular Organisms There are no special respiratory organs in unicellular and aquatic organisms such as Amoeba and Paramecium. Oxygen that dissolves in water diffuses into the body while carbon dioxide goes out of the...
LANDFORMS DUE TO WATER ACTION IN THE DESERTS
Wind erosion, transportation and deposition are most effective and widespread in desert regions, but few deserts in the world are entirely without rain or water. In some deserts, there are perennial rivers such as...