Earth’s Systems – Grade 11 Earth Science (Week 1 Day 2)

A set of question-and-answer flashcards covering key points about Earth’s four subsystems, their characteristics, and the interactions that make our planet habitable.

What are the four main subsystems of Earth?

Geosphere, Hydrosphere, Atmosphere, and Biosphere.

In Earth Science, how is a subsystem defined?

A smaller interacting system contained within the larger Earth system.

Why is Earth generally treated as a closed system for matter?

Because the total amount of matter is essentially fixed; gravity prevents significant mass from entering or leaving the planet.

Which Earth sphere is the largest and represents the planet’s solid portion?

The Geosphere.

What are rocks in the geosphere composed of?

Naturally occurring solid aggregates of minerals, organic material, or natural glass.

What is regolith?

A blanket of loose rock particles covering Earth’s surface.

Define the lithosphere.

The rigid outer part of the geosphere—crust and uppermost mantle—where tectonic plates are found, bounded by the atmosphere above and the asthenosphere below.

List Earth’s internal layers from the surface to the center.

Soil layer, crust, mantle, liquid outer core, solid inner core.

Why is the surface of the lithosphere uneven?

Erosion, weathering, transport processes, tectonic forces, and volcanic activity continually reshape it.

What does the hydrosphere include?

All of Earth’s water—liquid, solid, and vapor—including oceans, rivers, lakes, groundwater, and frozen water (cryosphere).

Approximately what percentage of Earth’s water is contained in the oceans?

About 71 percent.

What is the cryosphere?

The frozen portion of the hydrosphere, including glaciers, sea ice, and permafrost.

Is atmospheric water considered part of the hydrosphere?

It is often discussed separately, but it is inherently connected to the hydrosphere through the water cycle.

Which two gases make up roughly 99 percent of Earth’s atmosphere?

Nitrogen (78 %) and Oxygen (21 %).

Name the five primary layers of the atmosphere from lowest to highest.

Troposphere, Stratosphere, Mesosphere, Thermosphere, Exosphere.

In which atmospheric layer does most weather occur?

The Troposphere.

Which layer of the atmosphere contains most of the ozone?

The Stratosphere.

Where do meteors typically burn up, creating “shooting stars”?

The Mesosphere.

What causes temperature to rise in the thermosphere?

Absorption of energetic ultraviolet and X-ray radiation from the Sun.

What characterizes the exosphere?

It begins around 500 km altitude; gas atoms are so sparse they rarely collide and can escape into space.

What is the biosphere?

All life on Earth and the regions they inhabit, generally within a 20 km zone that spans parts of the lithosphere, hydrosphere, and atmosphere.

Where are most of Earth’s organisms found—lithosphere, hydrosphere, or atmosphere?

The Hydrosphere; most life forms live in the oceans.

How do the lithosphere, hydrosphere, and atmosphere interact to create a habitable environment?

They exchange matter and energy, regulating temperature, nutrient cycles, and conditions suitable for life, thereby supporting the biosphere.