Notes Flashcards
(23 cards)
Nitrogen is found in…
amino acids and proteins.
What percentage of the atmosphere is nitrogen?
73%
Nitrogen is also found in…
ammonia, nitrate, and nitrite that are found in many fertilizers.
Can plants use nitrogen directly from the atmosphere?
No, nitrogen is abundant, but plants can’t use it directly.
Certain plants such as legumes contain…
nitrogen-fixing bacteria.
Bacteria turn nitrogen into…
ammonia and nitrates, which are used by plants to make proteins.
When animals die, denitrifying bacteria turn nitrate back into…
nitrogen gas, which returns to the atmosphere.
Phosphorus is a component of…
nucleic acids such as DNA and RNA.
Where is phosphorus mainly found?
soil and rocks.
Rock and soil…
erode, releasing phosphorus as inorganic phosphate.
Some phosphate dissolves in water and is carried to the…
oceans, where it is used by marine organisms.
What incorporates phosphorus in plants?
Organic compounds
What eats plants in an ecosystem?
Consumers
What is primary productivity?
The measure of the rate of organic compound production in the ecosystem.
What controls the rate of production in an ecosystem?
Available nutrients
What happens when a limiting nutrient is in short supply?
Cycles slow down, limiting growth.
What happens if too much of a limiting nutrient enters an ecosystem?
Extreme producer growth called eutrophication.
What happens when the nutrient runs out?
Producers die, and decomposers break them down.
What do decomposers use up in the water?
Oxygen, causing hypoxic zones.
What is a keystone species?
A species that the rest of the ecosystem largely depends upon.
Ex: Beavers, wolves, starfish, sea otters.
What is a trophic cascade?
A predator reduces the abundance or alters the behavior of their prey. Lower prey density reduces their predation on the lower trophic levels.
Ex: sea otters.
