Biogeochemical Cycles

In this diagram of the nitrogen cycle, ______ can convert unusable nitrogen into a usable form the plant can use.

• Organism 1

• Organism 2

• Organism 3

• Organism 4

Using the diagram, choose ALL areas that represent a biotic factor by selecting the appropriate boxes.

• Cow

• Cow, Tree

• Bacteria

• Cow, Tree, Bacteria

A chemical spill kills all of the nitrogen-fixing bacteria in an ecosystem without directly harming any other organisms. Which organisms are most likely to be affected first by the loss of bacteria?

• producers

• carnivores

• herbivores

• decomposers

What is the phase of the carbon cycle that represents where glucose is broken down in the presence of oxygen?

• Photosynthesis

• Consumption

• Decomposition

• Cellular Respiration

Which human activities would have a negative impact on the carbon cycle?

• rotating crops

• burning fossil fuels

• walking to the park

• planting trees

• cutting down trees

All of the organisms in an ecosystem are interdependent, helping to maintain the equilibrium of the cosystem. Which of the following processes can bacteria perform that is not possible for the other members of a typical ecosystem?

• absorbing energy from sunlight

• preventing the erosion of topsoil

• using nitrogen from the atmosphere

• decomposing the remains of organisms

It is estimated that about one half of all commercial fertilizers ever produced have been applied to crops in the last 20 years. Of this fertilizer, only about half is incorporated into plant tissue and the remainder enters the environment. Which of these natural cycles is this most likely to impact?

• carbon

• nitrogen

• oxygen

• rock

All of the organisms in a typical ecosystem are interdependent, helping to maintain the equilibrium of the ecosystem and sustaining each other. Which of the following processes can bacteria perform that is not possible for the other members of a typical ecosystem?

• converting radiant energy into chemical energy

• conserving water

• nitrogen fixation for the nitrogen cycle

• decomposing the remains of dead organisms

Nitrogen fixation is a process in which_____ can change_____ gas into a form that_____ can use. 

• carbon-plants-oxygen

• bacteria-plants-oxygen

• bacteria-nitrogen-plants

• plants-nitrogen-bacteria

Which of the following choices contains two ways in which carbon dioxide enters the atmosphere?

• erosion and transpiration

• decomposition and respiration

• volcanic activity and photosynthesis

• 
  human activity and formation of fossil fuels