Earth's Support Of Life

1. About what fraction of Earth's surface is covered by water?

1/4

1/2

3/4

9/10

Approximately 71% of Earth's surface is covered by water, which is equivalent to about 3/4. This includes the oceans, seas, lakes, rivers, and other bodies of water.

Explanation

Approximately 71% of Earth's surface is covered by water, which is equivalent to about 3/4. This includes the oceans, seas, lakes, rivers, and other bodies of water.

2. In which state does water exist on Earth?

Solid only

Liquid only

Gas and liquid only

Solid, liquid, and gas

Water exists in three states on Earth: solid, liquid, and gas. In its solid state, water is ice, in its liquid state, it is water, and in its gaseous state, it is water vapor. This is due to the unique properties of water, such as its ability to freeze and boil at specific temperatures. These different states of water play a crucial role in various natural processes, such as the water cycle and the formation of weather patterns.

Explanation

Water exists in three states on Earth: solid, liquid, and gas. In its solid state, water is ice, in its liquid state, it is water, and in its gaseous state, it is water vapor. This is due to the unique properties of water, such as its ability to freeze and boil at specific temperatures. These different states of water play a crucial role in various natural processes, such as the water cycle and the formation of weather patterns.

3. Why is the sun necessary for animals to live on Earth?

Animals convert the sun’s energy into food

Animals convert the sun’s energy into water.

Animals require water to survive, and plants convert the sun’s energy into water.

Animals eat plants or other animals that eat plants, and plants convert the sun’s energy into food.

Animals require food to survive, and they obtain this food by eating plants or other animals that eat plants. Plants, on the other hand, convert the sun's energy through the process of photosynthesis into food. Therefore, the sun is necessary for animals to live on Earth because it provides the energy that plants need to produce food, which is then consumed by animals.

Explanation

Animals require food to survive, and they obtain this food by eating plants or other animals that eat plants. Plants, on the other hand, convert the sun's energy through the process of photosynthesis into food. Therefore, the sun is necessary for animals to live on Earth because it provides the energy that plants need to produce food, which is then consumed by animals.

4. Unlike on planets such as Venus and Mars, which gas makes up most of Earth's atmosphere?

Oxygen

Nitrogen

Water vapor

Carbon dioxide

Nitrogen makes up the majority of Earth's atmosphere. Oxygen, water vapor, and carbon dioxide are also present in the atmosphere, but in much smaller quantities compared to nitrogen.

Explanation

Nitrogen makes up the majority of Earth's atmosphere. Oxygen, water vapor, and carbon dioxide are also present in the atmosphere, but in much smaller quantities compared to nitrogen.

5. How did the cooling that occurred when Earth first formed lead to the formation of oceans?

Water from Earth’s core flowed up to the surface.

Lava from volcanic eruptions cooled into liquid water.

Steam released into the air formed clouds that produced rain.

Water vapor in space froze into ice that eventually fell to Earth and melted.

When Earth first formed, the cooling process caused water vapor to be released into the air. This water vapor then formed clouds, which eventually produced rain. As the rain fell to the surface, it accumulated to form the oceans. Therefore, the cooling of Earth led to the formation of oceans through the process of steam being released into the air and forming rain.

Explanation

When Earth first formed, the cooling process caused water vapor to be released into the air. This water vapor then formed clouds, which eventually produced rain. As the rain fell to the surface, it accumulated to form the oceans. Therefore, the cooling of Earth led to the formation of oceans through the process of steam being released into the air and forming rain.

6. Some of the water in Earth's oceans formed from the steam released as Earth's core first cooled. What was the source of much of the remaining water?

Meteors melted when they hit Earth’s surface.

Glaciers melted as they were turned toward the sun.

Earth’s gravitational pull attracted water from nearby planets.

Algae in the early seas produced water during photosynthesis.

Meteors are large objects that enter Earth's atmosphere and collide with its surface. When meteors hit the Earth, they can release large amounts of heat, causing the ice present on them to melt and contribute to the Earth's water. This process is known as impact melting. Therefore, the melting of meteors upon impact is a plausible explanation for the source of much of the remaining water on Earth.

Explanation

Meteors are large objects that enter Earth's atmosphere and collide with its surface. When meteors hit the Earth, they can release large amounts of heat, causing the ice present on them to melt and contribute to the Earth's water. This process is known as impact melting. Therefore, the melting of meteors upon impact is a plausible explanation for the source of much of the remaining water on Earth.

7. Why does Earth have an atmosphere but Mars and Mercury do not?

Mars and Mercury are too close to the sun.

No liquid water exists on Mars and Mercury.

The gravitational pull of Mars and Mercury is too small.

Ultraviolet radiation from the sun burned away the atmospheres of Mars and Mercury.

The explanation for the correct answer is that the gravitational pull of Mars and Mercury is too small. The gravitational force of a planet or celestial body determines its ability to hold onto its atmosphere. Since Mars and Mercury have weaker gravitational forces compared to Earth, they are unable to retain a significant atmosphere.

Explanation

The explanation for the correct answer is that the gravitational pull of Mars and Mercury is too small. The gravitational force of a planet or celestial body determines its ability to hold onto its atmosphere. Since Mars and Mercury have weaker gravitational forces compared to Earth, they are unable to retain a significant atmosphere.

8. If the tilt of Earth's axis was greater than 23.5 degrees, how would this affect the temperatures on Earth?

Temperatures would become more consistent over the surface of Earth.

Summer would be cooler and winter would be warmer.

Earth’s surface temperature would rise in every season.

The differences in temperature between summer and winter would be greater.

If the tilt of Earth's axis was greater than 23.5 degrees, it would cause the differences in temperature between summer and winter to be greater. This is because the tilt of the Earth's axis affects the angle at which sunlight hits different parts of the Earth throughout the year. With a greater tilt, the angle of sunlight would be more extreme, leading to more intense seasons. Summers would be hotter and winters would be colder, resulting in a larger difference in temperature between the two seasons.

Explanation

If the tilt of Earth's axis was greater than 23.5 degrees, it would cause the differences in temperature between summer and winter to be greater. This is because the tilt of the Earth's axis affects the angle at which sunlight hits different parts of the Earth throughout the year. With a greater tilt, the angle of sunlight would be more extreme, leading to more intense seasons. Summers would be hotter and winters would be colder, resulting in a larger difference in temperature between the two seasons.

9. The gas that insulates Earth and keeps it warm is _____

Carbon dioxide is the gas that insulates Earth and keeps it warm. It acts as a greenhouse gas, trapping heat in the atmosphere and preventing it from escaping into space. This phenomenon is known as the greenhouse effect. Without carbon dioxide and other greenhouse gases, Earth would be much colder and unable to support life as we know it.

Explanation

Carbon dioxide is the gas that insulates Earth and keeps it warm. It acts as a greenhouse gas, trapping heat in the atmosphere and preventing it from escaping into space. This phenomenon is known as the greenhouse effect. Without carbon dioxide and other greenhouse gases, Earth would be much colder and unable to support life as we know it.

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