universe is a system made up of the stars, planets and the space
surrounding them. The earth is the one of the planets in the universe.
Plants, animals and other organisms like man, inhabit the earth. For
many centuries man has witnessed and appreciated changes, which occur in
nature and within his immediate surroundings. For example many
thousands of years ago the Sahara desert was not there, instead the
entire area was covered with a thick forest. Due to changes in weather
the forest gradually disappeared and gave way to present desert. All
this gives us the concept about organic evolution.
The Concept of Organic Evolution
Explain the concept of organic evolution
is the gradual development of organisms from simple form to more
complex forms over a long duration of time. Evolution is marked by
emergence of new species from pre-existing species and the disappearance
of some species. The species that disappear are said to become extinct.
Key terms used in organic evolution
  • Carbon dating: This is a method of estimating the ages of dead materials of biological origin.
  • Natural Selection:
    This is selective force occurring in nature, which is responsible for
    eliminating the unfavourable traits to retain only favourable traits in
    the population.
  • Specie: These are organisms, which have ability to interbreed freely to produce fertile off springs.
  • Fossils: These are the remains of organisms that lived in the past, preserved naturally in rocks, peat or ice.
Importance of Studying Evolution
  1. It
    helps to understand the biological forces that cause organisms to
    develop from simple to more complex organisms to the extent of new
    species emerging
  2. It helps to know how different organisms relate


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