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SS 2 Biology (1st Term)



ADAPTATION Adaptation is defined as the ability of an organism to live successfully in a particular habitat as a result of its structure, appearance and behaviour. It is expected that every organism must adapt to its environment in order to survive. Plants and animals possess certain features which enable them to adapt to either aquatic or terrestrial habitats.   Animal Adaptation (1) Adaptation of Animals to Aquatic Habitat (i) Possession of streamlined body for easy movement in water, e.g. Tilapia fish and toad. (ii) Possession of fins for movement as in the case of fish and webbed toes as in toad (iii) Possession of gills for gaseous exchange in fish and tadpoles. (iv) Possession of swim bladder for the purpose of buoyancy in water, e.g. Tilapia fish. (v) Possession of tail for swimming, e.g. tadpoles. (vi) Possession of sticky undersurface for attachment to surfaces of objects, e.g. snails and flatworms.… Read More »ADAPTATION



Biological Association In a community, there exist different kinds of biological associations between organisms of different species. Some of these biological associations are beneficial, some are neutral while others are harmful.   Types of Associations Symbiosis Definition: This is a close association between two organisms in which one or both of them benefit from each other. Symbiosis is a beneficial association and each member is called a symbiont. This association can be further divided into 1. Mutualism 2. Commensalism   Mutualism Mutualism is the association between two organisms in which both of them benefit from each other. Examples of mutualism include: Algae and fungi in lichen; Protozoa in the intestine of termites; Nitrogen fixing bacteria in the root nodules of leguminous plants; Bacteria in the rumen of ruminants.   Evaluation Mention five different types of biological associations. What is mutualism?   Commensalism Commensalism is a relationship between two organisms of… Read More »ECOLOGICAL MANAGEMENT



CONSERVATION OF NATURAL RESOURCES Definition: Conservation is defined as the planned, control exploitation or judicious use of natural resources to ensure their continuous availability and to preserve the quality or original nature of the environment. In other words, conservation is the preservation of natural resources from loss, waste or exploitation through rational use and to ensure their continued use or availability and preserve the quality or original nature of the natural resources Natural resources can be renewable or non-renewable. (i) Renewable natural resources: These are natural resources that are recoverable.  Examples are rain, animals, plants, water, and food and soil. (ii)Non-renewable natural resources: These are resources which when exhausted cannot be replaced or recovered. Examples are mainly mineral resources like petroleum, coal, tin, copper etc.   Need or Reasons for Conservation (i) To prevent destruction of natural environment or to allow for continued use of natural resources for man’s benefits… Read More »CONSERVATION OF NATURAL RESOURCES



POLLUTION  Definition: Pollution is defined as the release of toxic or harmful substances into the environment by their natural forces or man and other animals to an extent that causes biological damage to man and his resources. In other words, pollution is the release of harmful substances into the environment, i.e., water, air and land in quantities or to the level that are harmful to man, animals and plants. The harmful substances that cause pollution in the environment are called pollutants. There are four main types of pollution. These are (a)Air pollution  (b)Noise pollution  (c) Land pollution  (d) Water pollution   The major air pollutants, their sources, harmful effects and their control   Air Pollutants Sources Effects Carbon monoxide   Burning of fuel in cars other combustion engines and some industrial processes It causes suffocation because it combine with haemoglobin and reduces its ability to carry oxygen which results in… Read More »ENVIRONMENTAL POLLUTION



Nitrogen Cycle Nitrogen is an abundant element in the atmosphere. It is an essential constituent of proteins, a group of substances found in all living cells. About 78% of air is composed of gaseous nitrogen. Plants cannot incorporate nitrogen gas into organic compound and therefore depend on various types of bacteria to make nitrogen available for them in a global cycle called the nitrogen cycle. In nature, nitrogen is constantly being removed from the soil and returned to it via the nitrogen cycle.   Conversion of Gaseous Nitrogen into Nitrogenous Compounds Gaseous nitrogen is converted into nitrates in the following ways The action of thunderstorms Nitrogen-fixing microorganisms During thunderstorms, nitrogen reacts with oxygen to form nitric oxide. The nitric oxide is oxidized to nitrogen peroxide which dissolves in rainwater to form nitric nitrous acids.  When these acids enter the soil, they combine with mineral salts to form nitrates. The nitrates… Read More »NITROGEN CYCLE



Introduction                                   Food production depends on the following Role of government in agricultural production Environmental factors required for food production 3Ways of improving crop production   Role of Government in Agricultural production The role of government in agricultural production include Provision of agro-chemicals Provision of financial assistance. Provision of high quality planting materials Provision of tractors and other implements Provision of extension services Establishment of river basin authorities Provision of storage and processing facilities Provision of effective transportation network Efficient quarantine measures Provision of research work   Environmental Factors Required for Food Production Environmental factors affecting food production include the biotic and abiotic factors.   Abiotic factors include: I. Rainfall  II. Temperature  III. Wind  IV. Sunlight  V. Relative humidity  VI. Solar radiation  VII. Edaphic factor; soil pH, soil texture, and soil structure.   Biotic factors affecting food production include  I. Soil organisms  II. Pests  III. Parasites     IV. Diseases   V. Weeds   VI.… Read More »FOOD PRODUCTION AND STORAGE



TERRESTRIAL HABITATS Organisms of the land are called terrestrial organisms. They include plants and animals that are found living on the ground and under the ground. Basically, terrestrial habitat is subdivided into four main parts, namely; marsh forest grassland/ savanna arid land/ desert   EVALUATION What are terrestrial organisms? List four types of terrestrial habitats   MARSH Marsh is a low land, flooded in rainy season and usually waterlogged because of poor drainage. The vegetation is predominantly of grasses and shrubs. When trees grow in a marsh, it is called a swamp. Marsh is a transition between the aquatic habitat and terrestrial habitat.   FORMATION OF A MARSH Marshes develop as a result of water overflowing its banks to accumulate on the adjoining coastal or low land area such as flood plains of rivers. This can be enhanced with extensive rainfall. When ponds and lakes are filled up with soil… Read More »TERRESTRIAL HABITATS



HABITAT (AQUATIC HABITAT) Habitat is a place where organisms (plants, microorganisms and animals) are naturally found e. g. the habitat of tadpole is the bottom of fresh water ponds or streams. There are three main types of habitats, namely; aquatic habitat (in or around water), terrestrial habitat (in or on land) and arboreal habitat (in or on trees) There are three kinds of aquatic habitat; marine/salt water habitat e.g. ocean, seas brackish water habitat (where salt and fresh water mix) e.g. delta, lagoon, bay Fresh water habitat (contain little or no salt) e.g. lakes, rivers, streams.   MARINE HABITATS Characteristics of marine habitats are as follow: The marine habitats constitute the largest habitat in the biosphere (70% of the earth’s area) They do not undergo sudden or rapid changes in physical factors such as temperature, PH and specific gravity. Hence they show the greatest stability of all habitats. Chemical composition… Read More »AQUATIC HABITAT

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