Week 10

Question 1

T/F:

N2 is directly available to most species

Answer 1

False

Question 2

T/F:

Nitrogen can exist in several different oxidation states

Answer 2

True

Question 3

Nitrification is ____

Answer 3

Oxidation of ammonia to NO2 and then to NO3

Question 4

T/F:

Denitrification is the reduction of NO3- and NO2- to N2 by aerobic bacteria

Answer 4

False

Anaerobic bacteria

Question 5

What do annamox bacteria do?

Answer 5

Conversion of NH3 and NO2- to N2

anaerobic

Question 6

For N assimilation, ___ ATP are needed per amide N

Answer 6

12

Question 7

Why are high levels of NH4+ toxic to both people and plants?

Answer 7

Dissipate H+ gradients across membranes

proton gradients needed to make neergy are ruined

Question 8

What does nitrate reductase do?

Answer 8

Reduces nitrate to nitrite

Question 9

What does nitrite reductase do?

Answer 9

Reduces nitrite to ammonium

Question 10

Where can you find nodules?

Answer 10

Roots of legumes

Question 11

Why does nitrogen fixation require anaerobic conditions?

Answer 11

O2 irreversibly inactivates nitrogenase

Question 12

What role do cyanobacteria play in terms of creating an anerobic environment?

Answer 12

Create an anaerobic environment in heterocysts

These cells lack PSII so no oxygen is produced

Question 13

How do plants avoid NH4 toxicity?

Answer 13

Rapidly convert the NH4+ into amino acids

Question 14

Which two enzymes are needed to convert NH4 into amino acids?

Answer 14

Glutamine synthetase (GS) and GoGAT

Question 15

T/F:

NADH-GOGAT is found in chloroplasts and Fd-GOGAT is found in plastids of non-photosynthetic tissues

Answer 15

False

Other way round

Question 16

What does the GS-GOGAT pathway form?

Answer 16

Glutamine and glutamate

Question 17

How are other amino acids formed from glutamate?

Answer 17

Aminotransferases transfer an amino group from Glu to an alpha-keto group

Question 18

What form is absorbed sulfur in plants?

Answer 18

It is found as sulfate

Question 19

How does sulfate from the soil become absorbed by plants?

Answer 19

Absorbed from the soil via an H+ SO42- symporter

Question 20

T/F:

Secondary metabolites have direct function in growth and development

Answer 20

False

Question 21

List the three major groups of secondary metabolites

Answer 21

Terpenes
Phenolics
Nitrogen-containing compounds

Question 22

T/F:

Secondary metabolites are mostly used in defence

Answer 22

True

Question 23

Which is the largest of the three secondary metabolite groups?

Answer 23

Terpenes

Question 24

T/F:

Terpens are built upon 6 carbon units

Answer 24

False

5

Question 25

What are terpenes usually synthesized from?

Answer 25

acetyl-coA or glycolytic intermediates

Question 26

Which two pathways are used to make terpenes?

Answer 26

Mevalonic acid pathway

Methylerythitol phosphate (MEP) pathway

Question 27

T/F:

Some terpenes are not secondary metabolites

Answer 27

True

Question 28

How many carbons would 2x isoprene molecules have?

Answer 28

10

Known as a mono terpene

Question 29

To form the 10-C precursor geranyl diphosphate (GPP) of all monoterpenes, which two molecules have to react together?

Answer 29

IPP and DMAPP

Question 30

What are pyrethroids used for?

Answer 30

Powerful insecticides

Question 31

What group is found in all phenolic compounds

Answer 31

Phenol group

Question 32

What is the shikimic acid pathway?

Answer 32

Converts carbohydrates to the aromatic amino acids

Question 33

Which group of secondary metabolites is lignin a part of?

Answer 33

Phenolics

Question 34

Which compound is known to give plants red, pink, purple and blue colours?

Answer 34

Anthocyanins

Question 35

T/F:

Anthocyanidin is anthocyanin with an added sugar

Answer 35

False

Remove a sugar from anthocyanin to form anthocyanidin