Pollution has been defined by Odum (1971) as “the undesirable change in the physical, chemical or biological characteristics of air, land and water that may affect the human life. The pollutants cause undesirable physical and biological changes. Man is searching for food and better
The soil in which salt crust is left due to evaporation of water is called saline soil and this problem is called salinity. A saline soil has electrical conductivity of its saturation equal to or greater than 4m.mho per centimeter and its exchangeable sodium
The soil which is saturated with water is called water logged soil and this problem is called water logging. Causes of water Logging Pakistan has one of the best canal systems in Pakistan. It is composed of 40790 canal miles. But some defects wete
The management of the earth resources to restore and maintain balance between human requirement and other species in the world is called conservation. Conservation includes continuous renewing of renewable resources. It is also applied to conserve non-renewable sources. 1 Air Air is several kilometers
The variety of living organisms in an ecosystem is called biodiversity. The exact number of species in the world is not known. The taxonomists have described about 1.4 million species. But taxonomists estimate that there are 4 to 30 million more species. Much of
The word arid means dry. The dry land is called arid land. This problem is called aridity. Arid climate is defined as the climate in which precipitation is less than the evapotranspiration in most part of the year. Deficiency of rainfall is a basic
Multiple Choice Questions (MCQs) The maximum percentage of energy changed into food is: (a) 10% (b) 20 (c) 30 (d) 5 Percentage of energy absorbed in atmosphere is: (a) 50 (b) 60 (c) 57 (d) 70 Which of the following is not tertiary consumer?
MODEL SUBJECTIVE QUESTIONS: What is ecosystem? Give its components. Give physiognomic characteristics. Write note on ecological energetics. Write note food chain, food web and trophic levels. Write note on ecological pyramids. Describe nitrogen cycle. Describe hydrological cycle. SHORT QUESTIONS: 1. What are consumers?
TERMS DEFINITIONS Ecosystem A community with its non-living environment is called ecosystem. Decomposers The microorganisms which decompose the bodies of dead animals and plants are called decomposes. Ecological energetic The flow of energy through an ecosystem is called ecological energetic. Productivity The rate at
Water is essential for all the life processes. About 80% of water is present in a living cell.– It covers about 73% of surface of the earth in the form of lakes, rivers, oceans. There is a continuous cycling of water between biotic and