Grade 10 slides on history of life on Earth by Thula

1. Grade 10: Diversity, Change and
Continuity
History of life on Earth

2. Lesson overview
 You will learn that Earth is very old
 You will learn that since the first living form appeared,
organisms have changed overtime.
 You will learn that our world today is filled with many different
and diverse species.

3. Earth is very old
• Since the very first living form
appeared, organisms have changed
over many times to survive.

4. Today our world is filled with many different
and diverse species

5. The history of life on Earth shows evidence
of two types of extinction
• Background extinction : is a continuous low-level
extinction
• Mass extinction : where many species become extinct at
one time

6. Scientific evidence shows that mass extinction
occurred five times over the course of millions
of years (5 billion)
• Extinction occurs when species are unable to adapt to the environmental
changes.
• Each period of mass extinction is followed by a period of mass speciation,
few individuals of species survive and diversity to replace extinct species
within the ecological niches.
• Fossil evidence proves that many of the organisms that live long ago are now
extinct.

7. MASS EXTINCTION

8. Changes in the climate
E.g. in ice age- Plants and animals were unable to adapt to the cold

9. Changes in the environment
• Meteorites crushing into the Earth and wiping out
most species.
• Shifting of the continental plates
• Volcanic activities

10. Biological factors
• Can trigger extinction as new species may
outcompete an old species leading to extinction.
• The increase in the human population has caused
the extinction of many plants and animals as we
invade their habitats.

11. sources
• Reece, J.B., Urry, L.A., Cain, M.L., Wasserman,k S.A. Minorsky, P.V. & Jackson, R.B. 2011.
Campbell Biology Ninth Edition. Pearson Education
• Taylor, D.J., Green, N.P.O. and G.W. Stout, 1998. Biological science. 3rd Edition,
Cambridge University Press.
• https://www.stuffyoushouldknow.com/podcasts/ice-ages.htm
• Michael Marshall, Timeline: The evolution of life;
https://www.newscientist.com/article/dn17453-timeline-the-evolution-of-life/
• Solomon, E.P., Berg, L.R. and Martin, D.W. 2005. BIOLOGY 7TH Edition.
• Belmont (USA): Brooks/Cole-Thomson Learning.