Earth Cycles and Systems

Unit Review Sheet

Facts and Definitions

Lesson 1: Matter and Energy

• Energy is the ability to do work.
• Radiant energy is emitted by a source in the form of invisible or visible waves.
• Electromagnetic energy is energy from the Sun that reaches Earth in the form of waves and rays (heat and light).
• Matter is anything that has mass and takes up space.
• A cycle is a repeating series of events; in the case of Earth cycles, a cycle is a repeating process, one that occurs regularly and periodically over time.

Lesson 2: Energy and Its Source

• Conduction is the transfer of heat energy between two solid pieces of matter.
• Convection is the transfer of heat energy by the movement of a liquid or gas.
• Radiation is the transfer of heat energy emitted in the form of light waves.
• The primary source of energy on the Earth is the Sun. Heat from the Sun is transferred to the Earth by radiation.

Lesson 3: Energy Flow in Ecosystems

• Autotrophs (producers) are organisms that make their own food using using light from the Sun (photosynthesis) or available chemicals when light is not present (chemosynthesis); they are capable of using or combining (fixing) carbon dioxide with other materials.
• Fixing is changing a material into biologically usable compounds for uses such as food or structure.
• Heterotrophs (consumers) cannot produce their own food and must use energy from a source outside their own bodies.
• Decomposers are organisms that break down dead or decaying matter.

Lesson 4: Matter and Plants

• Photosynthesis utilizes sunlight along with carbon dioxide and water to produce carbohydrates.
• A carbohydrate is a compound made up of bonds between carbon, hydrogen, and oxygen; bonds between two or more carbohydrates store energy.
• The position that an organism has in a food chain is called its trophic level.
• Biomass is biological material from living or recently living organisms. It is literally the total mass of an organism present in an ecosystem or environment.

Lesson 5: Carbohydrates, Plants, and Energy

• Carbohydrates are compounds that contain carbon, hydrogen, and oxygen bonded together. They can be simple — a single molecule, or complex.
• A complex carbohydrate is a chain of two or more carbohydrates bonded together.
• A chemical bond is an attraction between atoms that allows the formation of chemical substances. Chemical bonds either store energy when they form or release energy when they are broken.
• A starch is a complex carbohydrate produced by all plants and used as food storage.
• Cellulose is a structural component of the cell wall (found in all plant cells).

Lesson 6: Intro to Earth's Cycles

• An ecosystem is a community of organisms in which all organisms have a role in the maintenance and sustaining of the environment.
• Something that is periodic repeats at regular intervals.

Lesson 7: Oxygen Production and Life

• A reservoir is a place where something is kept in store.
• A depletion is a serious decrease or exhaustion of the abundance or supply of something.
• Cellular respiration is a process in all living things where stored energy is released by the breaking of chemical bonds to produce energy for survival.
• Glucose is an energy source produced by the process of photosynthesis. Glucose contains carbon, hydrogen, and oxygen.

Lesson 8: The Carbon Cycle

• The process where an organism that was once living is broken down in the environment is called decomposition.
• Detritus is waste material that is made up of dead plant matter, animal waste, and dead animals.
• A detritivore is an organism that consumes detritus and produces waste that is more easily broken down.
• The carbon store includes all carbon that is locked up in the environment in the remains of plants and animals that have failed to decompose.
• Decomposers break down organic matter into its simplest units (such as carbohydrates, water, and carbon dioxide).

Lesson 9: The Water Cycle

• Evaporation is the conversion of water from liquid to a gas.
• Condensation is the conversion of water from a gas into a liquid.
• Sublimation is the conversion of ice or snow directly into a gas.
• Evapotranspiration is the production of water vapor from the evaporation of water from the ground and from the transpiration of plants.

Lesson 10: Energy, Food Chains, and Food Webs

• A direct relationship is one in which an increase of the presence of one factor has a direct impact on the other factors (sunlight, photosynthesis, production of fruits and vegetables, etc.).
• An indirect relationship is one in which an organism benefits as a result of the relationship between two other components of an ecosystem (fruit or vegetable eaten by a primary consumer, for example).
• An ecological community is a group of actually or potentially interacting species living in the same place. They may interact through direct or indirect relationships.
• A food web is a graphical description of feeding relationships among species in an ecological community.
• A food chain is a representation of the predator-prey relationships between species within an ecosystem or habitat.
• Something that is abiotic is a non-living chemical or physical factor in the environment (light, temperature, nitrogen, etc.).

Lesson 11: The Nitrogen Cycle

• Soil fertility is the abundance of nutrients in soil that is beneficial for the growth of producers.
• Fertilizer is a compound or substance that supplies nutrients to plants. It can improve or change soil fertility.
• Equilibrium refers to the condition of a system in which competing influences are balanced.
• Leaching is the loss of water-soluble plant nutrients from the soil, due to rain and irrigation.
• Eutrophication occurs when too many nutrients enter a body of water (often due to leaching and fertilizer runoff), aquatic plants grow too much, and plant overgrowth uses up the available oxygen in the water, causing fish to die.

Final Project: A Sustainable Farm

• Sustainable farming methods allow a farm to work in harmony with the carbon, water, and nitrogen cycles.