Earth's Four Spheres: Understanding the Basics

Earth's Four Spheres

Lithosphere

• Consists of all Earth's water (solid, liquid, and gas)

Hydrosphere

• Includes oceans, lakes, groundwater, ice, and clouds
• Comprises 97% of Earth's water, with oceans holding the majority
• Encompasses water above, on, and below Earth's surface

Atmosphere

• A layer of gases surrounding Earth
• Extends hundreds of kilometers upwards from Earth's surface
• Held in place by Earth's gravitational pull
• Composed of 78% nitrogen gas (N2), 21% oxygen gas (O2), and other gases
• Critical to life on Earth, moderating surface temperatures and blocking UV radiation

Biosphere

• The zone around Earth where life can exist
• Supports life on land, in water, and several kilometers below the Earth's surface

Level of Organization

• Biosphere: largest level of organization, encompassing all life on Earth
• Ecosystem: a community of living organisms interacting with their environment
• Community: a group of populations living together
• Population: a group of individuals of the same species
• Organism: an individual living thing
• Organ system: a group of organs working together
• Organ: a self-contained part of an organism
• Tissue: a group of similar cells
• Cell: the basic unit of life
• Organelle: a specialized structure within a cell
• Molecule: the smallest unit of a substance

Photosynthesis

• The process of converting sunlight into chemical energy
• Occurs only in producers
• Produces sugar, which stores chemical energy
• Glucose is stored in leaves, stems, roots, and seeds, often converted to starch

Food Chains and Webs

• Food chains illustrate feeding relationships between organisms
• Food webs are interconnected food chains, illustrating the complexity of ecosystems

Invasive Species

• Introduced species that outcompete native species and harm the environment
• Most introduced species fail to establish themselves, but some thrive and outcompete native species

Controlling Introduced Species

• Chemical control methods
• Mechanical control methods
• Biological control methods

Classifications

• Extinct: species that no longer exists anywhere on Earth
• Extirpated: species that no longer exists in a specific area
• Endangered: species facing imminent extinction
• Threatened: species likely to become endangered if factors reducing its survival are not changed
• Special Concern: species that may become threatened or endangered

Biotic and Abiotic Factors

• Biotic factors: all living organisms, their remnants, and byproducts in an ecosystem
• Abiotic factors: non-living elements like temperature, wind, water, minerals, and air

Equilibrium

• A state of an ecosystem with relatively constant conditions over a period of time
• Established when abiotic conditions are stable and balanced

Explore the four spheres of Earth, including the Lithosphere, Hydrosphere, Atmosphere, and learn about their composition and characteristics. Learn about the Earth's water, gases, and more.