Week 10 Flashcards
T/F:
N2 is directly available to most species
False
T/F:
Nitrogen can exist in several different oxidation states
True
Nitrification is ____
Oxidation of ammonia to NO2 and then to NO3
T/F:
Denitrification is the reduction of NO3- and NO2- to N2 by aerobic bacteria
False
Anaerobic bacteria
What do annamox bacteria do?
Conversion of NH3 and NO2- to N2
anaerobic
For N assimilation, ___ ATP are needed per amide N
12
Why are high levels of NH4+ toxic to both people and plants?
Dissipate H+ gradients across membranes
proton gradients needed to make neergy are ruined
What does nitrate reductase do?
Reduces nitrate to nitrite
What does nitrite reductase do?
Reduces nitrite to ammonium
Where can you find nodules?
Roots of legumes
Why does nitrogen fixation require anaerobic conditions?
O2 irreversibly inactivates nitrogenase
What role do cyanobacteria play in terms of creating an anerobic environment?
Create an anaerobic environment in heterocysts
These cells lack PSII so no oxygen is produced
How do plants avoid NH4 toxicity?
Rapidly convert the NH4+ into amino acids
Which two enzymes are needed to convert NH4 into amino acids?
Glutamine synthetase (GS) and GoGAT
T/F:
NADH-GOGAT is found in chloroplasts and Fd-GOGAT is found in plastids of non-photosynthetic tissues
False
Other way round
What does the GS-GOGAT pathway form?
Glutamine and glutamate
How are other amino acids formed from glutamate?
Aminotransferases transfer an amino group from Glu to an alpha-keto group
What form is absorbed sulfur in plants?
It is found as sulfate
How does sulfate from the soil become absorbed by plants?
Absorbed from the soil via an H+ SO42- symporter
T/F:
Secondary metabolites have direct function in growth and development
False
List the three major groups of secondary metabolites
Terpenes
Phenolics
Nitrogen-containing compounds
T/F:
Secondary metabolites are mostly used in defence
True
Which is the largest of the three secondary metabolite groups?
Terpenes
T/F:
Terpens are built upon 6 carbon units
False
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