Lesson 1 Earth’s Support of Life Study Guide
1. What are the three most common gasses in the Earth’s atmosphere?
The three most common gasses in Earth’s atmosphere are nitrogen,
oxygen, and carbon dioxide.
2. What are the five basic necessities that organisms on Earth need to
survive?
The five basic necessities that organisms need to survive on Earth are
water, air, a source of energy, shelter, and waste disposal.
3. What is needed for photosynthesis and what is created by that same
process?
Sunlight, carbon dioxide, and water are needed for photosynthesis and it
produces glucose (a sugar) and oxygen.
4. Where did the water come from to fill the first oceans on Earth?
The water for the first oceans came from three sources – water vapor
escaping from volcanic eruptions, icy comets, and meteors.
5. What keeps the Earth’s atmosphere in place?
The atmosphere is held in place by Earth’s gravity.
6. What fraction would represent approximately how much water is on Earth?
The Earth’s surface is covered by almost 75% or ¾ water.
7. How does Earth’s location affect its temperature when compared with
Mars or Mercury?
Mars is too cold to support life because it is farther from the sun than Earth
is.
8. Explain what the Earth’s rotation is and why it’s important to life on Earth.
The Earth’s rotation is the spinning on its axis. This happens in a little less
than 24 hours and gives the planet night and day. It also ensures that Earth
gets a consistent amount of light. Water would not exist in all three states
on Earth without this rotation.
9. Explain what the Earth’s revolution is and why it’s important to life on
Earth.
The Earth’s revolution is its orbit around the sun. This happens in
approximately 365 days. The change in seasons is another result of this
process.
10. How did the cooling that occurred when Earth first formed lead to the
formation of oceans?
Steam released into the air formed clouds that produced rain.
11. What is ozone and why is it essential to the existence of life on Earth?
Ozone is three atoms of oxygen that are combined into an ozone molecule.
It has the ability to shield the surface of the planet from harmful ultraviolet
radiation. Without the ozone, life on Earth would not be possible.
12. What makes it possible for water to exist in all three states on Earth?
Water exists on Earth in all three states of matter because of Earth’s
distance from the sun and its rotation.
13. Why is the sun necessary for all plants to live on Earth?
The sun is necessary for plant life on Earth because it provides the energy
for plants to perform photosynthesis.
14. Why is the sun necessary for all animals to live on Earth?
The sun is necessary for animal life on Earth because it allows for
photosynthesis in plants (which animals eat and then other animals eat
those animals) and it keeps Earth at the temperatures that animals need to
survive.