Global Systems Flashcards
Why can’t organisms absorb nitrogen, and how do they?
Due to its gaseous state, so they rely on a process called fixation to obtain nitrogen in a usable form.
Why is nitrogen important in humans and plants?
Humans: Cells need it to make DNA and proteins
Plants: to make chlorophyll
What are the forms that nitrogen can exist in?
N2 (inert nitrogen gas in atmosphere)
Nitrites (NO2-) and nitrates (NO3-)
Ammonium (NH4+) and Ammonia (NH3)
What does nitrogen fixing bacteria in soil convert?
Nitrogen gas (N2) into ammonia (NH3)
What does nitrogen fixing bacteria in roots of legume plants convert?
Nitrogen gas (N2) into nitrates (NO3-)
What does lightning convert, and how?
Nitrogen gas (N2) -> Nitrites (NO2-) -> Nitrates (NO3-)
Energy from lightning breaks nitrogen molecules into nitrogen atoms. These atoms combine with oxygen in air, forming nitrogen oxides (NO2). These dissolve in rain to form nitrates (NO3), that enter soil with the rain.
What is the second step in the nitrogen cycle?
Ammonification: When decomposers break down organic matter into ammonia (and ammonium ions) - NH3- or NH4+
What is the third step of the nitrogen cycle?
Nitrification: Converts ammonium ions (NH4+) into nitrites (NO2-) and nitrates (NO3-) by nitrifying bacteria in soil
What is step four of the nitrogen cycle?
Denitrification: Chemical reduction process that converts nitrates (NO3-) into nitrogen gas (N2)
What is the albedo effect?
Light-coloured surfaces return a large part of the sunrays back to the atmosphere (high albedo).
- Clean, white clouds and fresh snow and ice
Dark surfaces absorb the rays from the sun (low albedo).
- Exposed land, water and vegetation have diminishing returns
Layers of atmosphere
Troposphere
Stratosphere (ozone layer absorbs UV radiation)
Mesosphere
Thermosphere
Exosphere
