Which statement defines net primary productivity? 

A)  It is the rate at which producers use chemical energy through respiration. 
B)  It is the rate of photosynthesis plus the rate of respiration. 
C)  It is the net rate at which producers convert sugar into biomass. 
D)  It is the rate at which producers manufacture chemical energy through photosynthesis.

More than 50% of Canada's plant and animal species are represented within Canada's national parks.

Which letter in the diagram corresponds to the zone in which the bacteria have not started the decay of degradable,oxygen-demanding wastes?

Species that have capacity for a high rate of population increase are called K-selected.

What is happening to the Earth's supply of concentrated,usable energy? 

A)  It is being steadily depleted. 
B)  It is being steadily converted to higher-quality forms. 
C)  It is being steadily replenished. 
D)  It is being steadily converted to more usable forms.

What happened to global per capita meat production between 1961 and 2013? 

A)  it decreased fivefold 
B)  it remained steady 
C)  it doubled 
D)  it increased fivefold

What is the most desirable type of coal,due to its high heat content and low sulphur content? 

A)  peat 
B)  lignite 
C)  bituminous 
D)  anthracite

Which letter in the diagram indicates the process in which water flows underground to the oceans?