1. Tardigrade
  2. Question
  3. Biology
  4. Read the following four statements (A - D). (A) Both photophosphorylation and oxidative phosphorylation involve uphill transport of protons across the membrane. (B) In dicot stems, a new cambium originates from cells of pericycle at the time of secondary growth. (C) Stamens in flowers of Gloriosa and Petunia are polyandrous. (D) Symbiotic nitrogen fixers occur in free-living state also in soil. How many of the above statements are right?

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Q. Read the following four statements (A - D).
(A) Both photophosphorylation and oxidative phosphorylation involve uphill transport of protons across the membrane.
(B) In dicot stems, a new cambium originates from cells of pericycle at the time of secondary growth.
(C) Stamens in flowers of Gloriosa and Petunia are polyandrous.
(D) Symbiotic nitrogen fixers occur in free-living state also in soil. How many of the above statements are right?

AIPMTAIPMT 2012Mineral Nutrition

Solution:

Polyandrous condition (having large and indefinite number of stamens) is present in Gloriosa (family liliaceae) and Petunia (family solanaceae). Nitrogen fixation is the conversion of inert atmospheric nitrogen into utilizable compounds of nitrogen like nitrate, ammonia, amino acids, etc. Biological nitrogen fixation is performed by free living and symbiotic bacteria and cyanobacteria. Symbiotic nitrogen fixers occur in association with roots of higher plants. For e.g., Rhizobium is nitrogen fixing bacterial symbiont of papilionaceous roots and Frankia is symbiont in root nodules of several non-leguminous plants like Casuarina. Both Rhizobium and Frankia live free as aerobes in the soil and develop the ability to fix nitrogen only as symbionts when they become anaerobic.