part 4

Question 1

symbiotic nitrogen fixation

Answer 1

process in which the bacteria lives inside the root nodule of the plant and fixes nitrogen eg., Rhizobium, anabaena, nostoc

Question 2

rhizobium

Answer 2

rhizobium lives free as aerobe in the soil but is unable to fix nitrogen because nitrogen is sensitive to oxygen

Question 3

what causes the curling of the root hairs

Answer 3

since rhizobium is unable to fix nitrogen living as a free aerobe it collects itself near the roots and secrete nod factors that cause curling of roots

Question 4

what happens to the cortical cells

Answer 4

the bacteria produces infection thread which infects the cortical cells and they swell up. along with it, the bacteria also starts dividing and they form colonies called bacteroids

Question 5

which enzyme does the bacteria produce

Answer 5

the bacteria produces the enzyme nitrogenase. it is sensitive to oxygen

Question 6

what are the functions of leghemoglobins

Answer 6

Host cells develop leghemoglobin which are mainly pink or red in color and it traps the oxygen.

Question 7

nitrogenous enzyme converts into

Answer 7

ammonia

Question 8

now ammonia is converted into

Answer 8

since ammonia is not essential for plants it converts into amino acids or nitrates\nitrites or glutamic acid