Q. No.Which of the following is free living nitrogen fixing cyanobacteria?
(1) Anabaena
(2) Azotobacter
(3) Beijernickia
(4) Rhodospirillum
(1) Anabaena
(2) Azotobacter
(3) Beijernickia
(4) Rhodospirillum
Rhizobium
(1) Rod shaped
(2) Legume-bacteria relationship
(3) Has relationship with roots of several legumes such as alfalfa, sweet clover sweet pea, Lentils, garden Pea, broad bean and clover beans
(4) All of these
Rhizobium and Frankia
(1) Free living in soil
(2) Act as symbiont and fix nitrogen
(3) One is found on the roots of non-leguminous plants
(4) All of these
The central portion of nodule is pink in color due to
(1) Leg- haemoglobin
(2) Haemoglobin
(3) RBC
(4) 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.
1. b-a-d-c-e-g-f-k-i-h-j
2. b-a-c-d-g-e-f-k-h-j-i
3. b-a-d-c-e-g-k-f-h-j-i
4. a-b-c-d-e-g-k-f-j-i-h
Which of the following does not happen during nodule formation?
(1) Rhizobium bacteria contact a susceptible root hair, divide near it
(2) Successful infection of root hair causes it to curl
(3) Infected thread carries the bacteria to the inner cortex
(4) The bacteria get modified into rod shaped bacteroides and cause inner cortical and endodermal cells to divide
Nodule formation is a result of
(1) Division and growth of cortical cells
(2) Division and growth of pericycle cells
(3) Division and growth of endodermal cells
(4) Both A and B
Enzyme Nitrogenase is
(1) Highly sensitive to the molecular oxygen
(2) Least sensitive to the molecular oxygen
(3) Highly sensitive to carbon dioxide
(4) Least active enzyme
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