Which of the following is not true about soil?
P. Soil not only supplies minerals but also harbours nitrogen fixing bacteria and other microbes
Q. It holds water
R. It supplies air to the roots
S. It acts as a matrix that stabilises the plant
T. It is a source of photosynthate
U. It is positively geotropic without any exception

  • S, T and U

  • T and U
  • S and U
  • R and T

Which of the following micronutrients does not form components of fertiliser?

  • Cu, Mn

  • Zn, K

  • Fe, Cu

  • Cu, Zn

Which of the following macronutrients does not form components of fertiliser?

  • N,P

  • P,S

  • K,S

  • S,Zn

Nitrogen:
Find the incorrect one.

  • Plants compete with microbes for it.
  • It is a limiting nutrient for both natural and agricultural ecosystem
  • Nitrogen has triple covalent bonds
  • Nitrogen fixation is conversion of nitrogen into nitrate

In nature, ……….. and ……….. provide enough energy to convert Nitrogen to nitrogen oxides (NO, NO2, N2O).

  • Lightning, Forest fires

  • Industrial combustions, UV radiation

  • Forest fire, Lightning

  • Lightning, UV radiation

Decomposition of organic nitrogen of dead plants and animals into ammonia is called

  • Nitrogen Fixation

  • Ammonification

  • Nitrification

  • Denitrification

Electrical nitrogen fixation leads to

  • Formation of Nitrate

  • Formation of Nitrite

  • Formation of Ammonia

  • Formation of Nitrogen

Ammonia is first oxidized to nitrite by the bacteria except

  • Nitrosomonas

  • Nitrococcus

  • Nitrobacter

  • All of these

Nitrification does not include

  • Conversion of ammonia to nitrite

  • Conversion of nitrite to nitrate

  • Conversion of nitrogen to ammonia

  • Both B and C

The nitrifying bacteria are

  • Photoautotroph

  • Chemoautotroph

  • Nitrotroph

  • Organotroph

Denitrification occurs in

  • Leaves

  • Roots

  • Soil

  • Environment

Plants absorb which form of Nitrogen?

  • Ammonia

  • Nitrate

  • Nitrite

  • Nitrogen

The reduction of absorbed nitrate occurs

  • In leaves

  • In roots

  • In soil

  • In air

Denitrification is carried by

  • Pesudomonas

  • Thiobacillus

  • Nitrobacter

  • Both A and B

Reduction of nitrogen to ammonia by living organisms is called as

  • Electrical Nitrogen Fixation

  • Biological Nitrogen Fixation

  • Industrial Nitrogen Fixation

  • Both B and C

Which of the following enzyme is exclusively in prokaryotes?

  • Nitrogenase

  • Pyruvate kinase

  • Glucokinase

  • Enolase

Nitrogenase converts

  • Nitrate to Nitrite

  • Nitrogen to Ammonia

  • Nitrogen to Nitrite

  • Nitrogen to Nitrate

Which of the following is symbiotic nitrogen fixer?

  • Rhodospirillum

  • Azotobacter

  • Beijernickia

  • Rhizobium

Which of the following is free living nitrogen fixing cyanobacteria?

  • Anabaena

  • Azotobacter

  • Beijernickia

  • Rhodospirillum

Rhizobium

  • Rod shaped

  • Legume-bacteria relationship

  • Has relationship with roots of several legumes such as alfalfa, sweet clover sweet pea, Lentils, garden Pea, broad bean and clover beans

  • All of these

The most common association on roots is as

  • Lichens

  • Nodules

  • Beads

  • Pneumathodes

Rhizobium and Frankia

  • Free living in soil

  • Act as symbiont and fix nitrogen

  • One is found on the roots of non-leguminous plants

  • All of these

The central portion of nodule is pink in color due to

  • Leg- haemoglobin

  • Haemoglobin

  • RBC

  • Myoglobin

These are the events of Nodule formation:
a. Rhizobia get attached to epidermal and root hair.
b. Rhizobia multiply and colonise the surroundings of roots
c. Bacteria invade the root hair
d. The root hairs curl
e. An infection thread is produced
f. Bacteria are released from the thread into the cells
g. Infection thread carries the bacteria into the cortex of the root
h. The release of bacteria into cortex leads to the differentiation of specialised nitrogen fixing cells
i. Establishment of a direct vascular connection with the host for exchange
j. Nodule is formed finally
k. Initiation of nodule formation in the cortex of the root
Arrange them in order.

  • b-a-d-c-e-g-f-k-i-h-j
  • b-a-c-d-g-e-f-k-h-j-i
  • b-a-d-c-e-g-k-f-h-j-i
  • a-b-c-d-e-g-k-f-j-i-h

Which of the following does not happen during nodule formation?

  • Rhizobium bacteria contact a susceptible root hair, divide near it

  • Successful infection of root hair causes it to curl

  • Infected thread carries the bacteria to the inner cortex

  • The bacteria get modified into rod shaped bacteroides and cause inner cortical and endodermal cells to divide

Nodule formation is a result of

  • Division and growth of cortical cells

  • Division and growth of pericycle cells

  • Division and growth of endodermal cells

  • Both A and B

To produce two molecules of ammonia, how many ATP are hydrolysed?

  • 16

  • 8

  • 4

  • 32

Enzyme Nitrogenase is

  • Highly sensitive to the molecular oxygen

  • Least sensitive to the molecular oxygen

  • Highly sensitive to carbon dioxide

  • Least active enzyme

To protect nitrogenase from oxygen, which of the following in nodule will act as scavenger

(1) Leg-haemoglobin

  • (3) Both  and 2.

  • (2) Anaerobic mode of life

  • 3

  • (4) Myoglobin

The nitrogen fixing bacteria are

  • Always free living

  • Generally free living aerobes but during nitrogen fixing event it becomes anaerobic

  • Always anaerobic

  • Generally anaerobic but under nitrogen fixing event, it becomes aerobic

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