Ex. 20 Nitrate Reduction

Question 1

in anaerobic respiration what is final enzyme complex and TEA

Answer 1

reductase, TEA is not O2

Question 2

nitrate reductase

Answer 2

produced by facultatively anaerobic bacteria. reduces (adds e- or removes O2 atoms from) nitrate (NO3-)

Question 3

advantage of using nitrate reductase

Answer 3

facultative anaerobe can substitute N03- for O2 as TEA during cellular respiration

Question 4

reduction of nitrate produces nitrite formula

Answer 4

NO3- +2e- +2H+ —> NO2- + H2O in anaerobic conditons

Question 5

media for nitrate reduction (presence of nitrite)

Answer 5

nitrate broth, contains large amounts of nitrate

Question 6

nitrate reagent a and b when reacted w/nitrite will turn

Answer 6

media red, indicating +ive test for nitrate reduction production

Question 7

3 explanations for absence of nitrite in broth

Answer 7

1. bacteria do not reduce nitrate (-ive test)
2. reduce nitrate to nitrite (N02-) but further reduced to ammonia (NH3)
3. Denitrification reduce nitrate to nitrite (N02-) but further reduced to nitrogen gas (N2)

Question 8

why necessary to add zine, reagent c

Answer 8

inorganic catalyst that reduces nitrate, yielding nitrite. any remaining nitrate will be converted to nitrite and turn broth red

Question 9

red colour before zinc and after since means

Answer 9

before zinc means +ive test for nitrate reductase. after zinc and broth is red means -ive test for nitrate reductase