Ecosystem Nutrients and Energy

What is the original source of almost all energy in most ecosystems?

• carbohydrates
• sunlight
• water
• carbon

An organism that produces its own food supply from inorganic compounds is called a(an)

• heterotroph
• consumer
• detritivore
• autotroph

A collection of organisms that belong to different populations but all live in the same area and interact with one another.

• Population
• Ecosystem
• Community
• Ecosphere

What is one of the most important processes that removes carbon from the atmosphere? 

• photosynthesis
• cellular respiration
• erosin
• soil respiration

Where do animals get nitrogen from?

• soil
• air
• water
• plants

Matter on Earth is limited, so it must be used ____________________________.

• only once
• over and over again
• by only animals
• at night only

What role do animals play in the carbon cycle?

• absorb carbon dioxide from the atmosphere
• give off carbon dioxide
• combustion
• decomposing matter

What is a population?

• A habitat.
• A group of individuals of the same species that live in the same area.
• A predator.
• The prey.

Corn planted in a field that has been previously planted with legumes and then plowed under is likely to be

• more productivie because bacteria living on the roots of legumes fix nitrogen in the soil.

• less productive because legumes remove phosphorous from the soil.

• less productive because the legumes have already taken all the nitrogen, carbon and phophorus from the soil.

Nitrogen fixation is carried out primarily by

• humans

• plants

• bacteria