The Earth is able to support life due to key characteristics like the presence of liquid water, its ability to maintain heat from both its core and the Sun, and the existence of an atmosphere. Life first began in water, as the earliest photosynthetic organisms used sunlight, carbon dioxide and water to produce oxygen. Maintaining heat allows photosynthesis and the right balance of gases, while the atmosphere provides surface temperature regulation and protects from extreme temperature fluctuations. Other planets lack some of these necessary conditions to sustain life over long periods.

1. Life on Earth
EARTH AND LIFE SCIENCE
Chapter 1 │ Lesson 3

2. •What are
the different
planets in
the solar
system?

3. •What makes
the Earth
different
from the
other
planets?

4. •Why do you
think the
Earth is the
only planet
that is able
to sustain
life?

5. •Do you
think there
are life
outside the
Earth?

6. All the planets in the
solar system share the
same origin as the
Earth—they all came
from dust particles that
combined through
accretion.

7. Some important
characteristics that are
necessary in supporting
life include the
presence of liquid
water, its ability to
maintain heat and the
existence of
atmosphere

8. Why do you think
the presence of
water is
important for life
to exist?

9. Presence of water
• Life would not have begun
without water. The presence of
water allowed the first
photosynthetic organisms to
thrive. Organisms such as
cyanobacteria used sunlight,
carbon dioxide, and water to
produce biomass and oxygen,
an essential component of the
atmosphere. These single-celled
organisms would then evolve
into the organisms present
today.

10. Where do you think
water on Earth come
from?

11. Where do you think
water on Earth come
from?

12. Why do you think
the ability of
Earth to maintain
heat is important
for life to exist?

13. The ability of the Earth to
maintain heat
• The heat that drives the different
systems necessary to support life
on Earth comes from two sources;
from Earth and from the Sun. heat
coming from the Earth is caused
by radiogenic heat from the
radioactive decay of materials in
the core and mantle and extruded
via active tectonic activities, such
as volcanism and plate movement.

14. The ability of the Earth to
maintain heat
• Heat is also provided by the sun. as
radiation from the sun enters Earth,
some of the heat is trapped by the
atmosphere. This causes the
greenhouse phenomenon needed by
plants to carry on with
photosynthesis. Photosynthesis also
ensures the right amount and flow
of gases on Erath. Without it, there
would be too much greenhouse
gases that would cause global
warming.

15. Why do you think
the presence of
atmosphere is
important for life
to exist?

16. The presence of
atmosphere
• A greenhouse effect is just
one of the many benefits
of having an atmosphere.
Having an atmosphere
also greatly influences
surface temperature,
weather, and climate,
which are essential to the
formation of life and
biodiversity on Earth.

17. • These dark, narrow, 100 meter-long
streaks called recurring slope lineae
flowing downhill on Mars are
inferred to have been formed by
contemporary flowing water.
Recently, planetary scientists
detected hydrated salts on these
slopes at Hale crater, corroborating
their original hypothesis that the
streaks are indeed formed by liquid
water. The blue color seen upslope
of the dark streaks are thought not
to be related to their formation, but
instead are from the presence of the
mineral pyroxene. The image is
produced by draping an
orthorectified (Infrared-Red-
Blue/Green(IRB)) false color image
(ESP_030570_1440) on a Digital
Terrain Model (DTM) of the same
site produced by High Resolution
Imaging Science Experiment
(University of Arizona). Vertical
exaggeration is 1.5.
• Credits: NASA/JPL/University of
Arizona

18. Why is it that
the Earth is
the only
planet able to
support life?