12th Zoology

Population Explosion

Population Explosion

Demographic statistics : Terminologies

Fertility is the actual production of offspring.
Birthrate is the number of births in a year per thousand persons.
The total fertility rate is the number of children born to an
average woman in a population during her entire reproductive life. (Population Explosion)
The Zero Population Growth Rate (ZPG) is the number of births
by which people are just replacing themselves.
Mortality or death rates is the number of deaths per thousand
persons in any given year.

Growth rates

Death rate subtracted from birthrate gives the natural increase of a population. The total growth rate includes immigration and emigration, as well as births and deaths.

Life span and Life expectancy

Life span is the oldest age to which a species is known to survive.
Life expectancy is the average age that a newborn infant can expect to attain in any given society.

Population Explosion

The rapid and dramatic rise in world population has occurred over the last few hundred years. The world’s population increased from 1.65 billion in 1900 to 3.02 billion in 1960 and reached 6.1 billion in 2000. Thus the size of the population nearly quadrupled in the span of 100 years, a historically unprecedented rate of increase. This sudden increase in population is called as Population Explosion or Population Bomb or Population Trap.

Regions with majority of world population

The major regions of population concentration are the East Asian
Region, South Asian Region and West European Region.

The East Asian Regions : The largest populated areas. It includes countries like China, Korea, Vietnam, Cambodia, Japan and Indonesia with one fourth of the total population of the world.

The South Asian Regions : The countries with second largest
population concentration. India, Bangladesh, Myanmar, Pakistan and Srilanka are the South Asian countries accounting for 20% of the global population. (Population Explosion)

The West European Region : has the third largest population
concentration. European countries, Mediterranean and Arabian
countries and British islands are the examples.

Reasons for the population Explosion

The main reason for slow and fluctuating population growth prior to early 1800’s was the prevalence of diseases such as small pox, diphtheria, measles and scarlet fever. In addition, epidemics of diseases such as typhoid fever, cholera and plague eliminated large number of adults. Famines also were not unusual. Biologically speaking, prior to 180s the population was
essentially in a dynamic balance with natural enemies and other aspects of environmental resistance. High reproductive rates were largely balanced by high mortality. (Population Explosion)

Since the 19th centuary

  • discoveries of vaccination provides protections to many of the infectious agents
  • discovery of antibiotics is a major breakthrough in the medical history,
  • improvements in agricultural techniques,
  • improvements in the nutrition and
  • better sanitation and personal hygiene

brought about spectacular reductions in mortality, especially among infants and children. The birth rate has remained high. So the human population entered into exponential growth, as they were freed from natural enemies and other environmental restraints. (Population Explosion)

Related Topics in Zoology:

Bio Zoology All Important Topics

  1. Human population and explosion

  2. Population Explosion

  3. Growing Population and Environmental impacts

  4. Global warming – Green house effect

  5. Ozone layer depletion

  6. Prevention and Effect of Ozone depletions

  7. Waste management – Classification

  8. Management of hazardous wastes

  9. Management of non hazardous wastes

  10. Waste water treatment and management

  11. Biodiversity

  12. Conservation of Biodiversity

  13. Characteristics of a Bioreserve

  14. Energy crisis and its environmental impact

  15. Steps to be taken to resolve energy crisis

  16. Environmental impacts of Power Sources

  17. Poverty and environment

  18. Fresh water crisis and management

Unit 6. APPLIED BIOLOGY Topic List Zoology

  1. Livestock and Management

  2. Important cattle breeds and their characteristics

  3. Milch breeds (or) Dairy breeds

  4. Dual purpose breeds & Draught breeds

  5. Exotic breeds of cattle

  6. Common diseases and control in Cattle – Contagious diseases

  7. Non-contagious diseases – Cattle

  8. Techniques adopted in cattle breeding

  9. Poultry Breeds

  10. Farming methods

  11. Poultry byproducts

  12. Fish Pond

  13. Edible Fishes Of Tamilnadu

  14. Medical Lab Techniques – Stethoscope

  15. Sphygmomanometer

  16. Haemocytometer

  17. Urine Sugar analysis

  18. ECG Electrocardiogram

  19. Computed Tomography CT

  20. Endoscopy (Laproscopy) techniques , Artificial Pacemaker

  21. Autoanalyser

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