EARTH SCIENCE 11/Q1L1

Characteristics of Earth and Its Subsystems

Earth is unique. It is termed as “planet of life” where matter and energy continue to flow. Most of
the cell’s processes requires energy from the Sun which is the main source of energy.
Since Earth is a closed system, energy flows to all of its living components to continue
various life processes and functions.
The different forms of energy also allow the recycling of matter needed for life.
What are the characteristics of Earth that make life possible?
What makes Earth different from the rest of the planets and other heavenly bodies
in the Solar System?

Earth is unique in our solar system because it has liquid water on its surface.
In fact, most of Earth’s surface is about 75 percent and covered with water.
 Water is present in the atmosphere, ground, freshwater lakes, rivers, streams; and
even in the polar ice caps.
 Water is also found in all living things. Some plants, for example, are as much as
90–95 percent water by weight. Adult humans are about 60 percent water by
weight.
 Water is important for the many life functions carried out by cells, tissues, and
organs. It helps dissolve certain nutrients and carry them throughout an organism.
 Water is also important for disposing of bodily wastes.

Scientists sometimes speak of Earth as having “Goldilocks” conditions—in other words, Earth is
“just right” for life as we know it.
 Earth’s place in the solar system as the third planet from the Sun, places it in an
area of space, that is not too hot and not too cold. If the Sun is closer to Earth, liquid
water would not be possible on this planet as all of it would evaporate and life forms
will not exist. If it were a little farther away, it would be colder and liquid water
would always be solid ice.
 Earth’s temperatures range from about –88˚C to 58˚C. All organisms on the planet
are adapted to temperatures within this range.

Earth has enough gravitational force to keep most gases close to its surface.
These gases make up the atmosphere. The planet’s atmosphere is approximately 21%
oxygen, a gas which is produced mostly by plants needed in respiration.
 Earth’s atmosphere also traps heat and protects the Earth from the damaging rays
of the Sun.
 The moon, the only satellite of Earth also plays important role for life.
o The moon’s gravitational pull causes tides. In some instances, the moon also
plays a role in the distribution of life forms, like in birds for migration and
navigation. It also has an effect on the planet’s polar shifts.

What makes earth habitable?

The following are the factors that make our planet capable of sustaining varied life forms
which thrive in the various ecosystems. Try to read and understand the factors that make our
planet habitable.
1. Temperature – This will influence how quickly atoms and molecules move.
- Most living things are limited to a temperature range of minus 15˚C to 115˚C.
Given this temperature range, H2O may still exist in liquid form being crucial to life.
- Among the other planets, only Earth’s surface has this temperature range.

2. Water – This matter dissolves and transports materials in and out of the cell.
 Only Earth has the right chemical materials like liquid water that could support life.
Right Atmospheric Conditions - The earth’s atmosphere is capable of trapping heat
and
houses the important atmospheric gases such as carbon dioxide and oxygen
which cause the earth to warm. It shields the surface from harmful radiation
through the ozone layer and Earth has the right size to hold a sufficient-sized
atmosphere.
- Earth’s atmosphere is about 100 miles thick.

3. Energy – Living things use light or chemical energy to run essential life processes. With
the
availability of sufficient energy, organisms can perform different metabolic reactions
through the cells. The inner planets such as Earth, get too much sunlight for life.
The outer planets get too little.

4. Right Distance from the Sun – Earth is in the Goldilocks Zone. A region with the just the
right
temperature to sustain life – not too cold not too hot.

5. Strong magnetic field - It shields us from the electromagnetic radiation coming from the
Sun.
The magnetic field deflects the radiation that may destroy the ozone layer.

6. Nutrients – These are materials that build and maintain an organism’s body.
The inner planets including Earth and moons have the same general chemical
components which makes nutrients easily available in the environment.
There are various biogeochemical cycles and geologic processes that
facilitate the transport and replenishment of the chemicals and nutrients required
by the biotic factors. Examples include water cycle and volcanism. The presence of
volcanoes, cycle of water and atmosphere, contribute to the flow of nutrients within
earth’s systems.

7. Greenhouse Gases - Without the greenhouse effect, Earth would be frozen, more than
60º F
colder. As mentioned above, the atmosphere is capable of trapping heat because of
greenhouse gases. Examples of greenhouse gases are water vapor, methane, and
carbon dioxide.

8. It is protected by the plate tectonics from the very hot temperature of the core – The
earth’s
core causes the convection currents in the mantle causing the overlaying
lithosphere to move. However, the surface is protected from heat from the core by
the lithospheric plates.
NAME: Section:

ACTIVITY 1

Directions: Describe the earth as a planet of life based on the specifications written inside the left
boxes. Write your descriptions on the right boxes. Do this in a sheet of paper.

Surface Features of Earth 

Atmospheric Features 

Relative Distance from 

The Sun

Presence of Water 

Influence of its Moon 

Other Factors 
Reflection: Answer the following questions on a separate sheet of paper.

1. What is a Goldilocks Zone?

2. What conditions need to exist in order for life to survive?

3. What temperature range is good for life?

4. What sort of atmosphere do living things need to survive?

5. Do living things need water to survive? Why?

6. What do organisms get from the food they eat? What is its use?

7. Is light necessary for living things? How?

8. How does the earth’s magnetic field affect life on earth?

9. Does it matter how massive the planet is? Why?

10. Describe three characteristics that make Earth suitable for life?
ACTIVITY 3

Crash Landing

Directions: A meteoroid has hit your spaceship! This happened while you are passing through
a stellar system with one (1) star and seven (7) planets, some of which has moons.
You are running out of fuel so you need to crash land on one of the planets. As going
down, you think of a planet you want to land, which you considered as your habitable
planet.
On a separate piece of paper (velum paper) you draw your own habitable planet
and explain why it’s habitable to you.