The seeds of a transformation in agriculture – which could ultimately be comparable in importance to the original Green Revolution – are about to be sown in several countries. This international project, which is being coordinated by a pioneering team at Britains university of Nottingham, has nitrogen fixation at its core. However, what is especially interesting is that this is not the typical nitrogen fixation associated with cleavers or Soya beans but the very real prospect of mainstream, non-leguminous crops such as rice or wheat being able to thrive with little, or no, artificial nitrogen. The search for non-leguminous crops able to exploit the value of nitrogen fixing rhizobia is nothing new. Almost as soon as the phenomenon of symbiotic nitrogen fixation was discovered in legumes, just over a century ago, researchers were trying to understand why other plants couldnt do the same. However, it was not until the late 1960s that researchers with more sophisticated equipment began to target the subject – encouraged by the knowledge that the production of artificial nitrogen utilizes alarming quantities of natural resources. Several options were explored, including the heart-transplant type transfer of genes from nitrogen fixing bacteria directly into the cells of a non-legume. Another possibility was to encourage the bacteria which occur naturally around plant roots to become more efficient at nitrogen fixation. In theory these super-efficient bacteria would then feed the roots of the rice or wheat, without invoking the traditional nodule forming relationship associated with nitrogen fixation in legumes. Under the glare of laboratory lights, both ideas had exciting potential. In practice, the chances of either becoming a commercial reality receded as time progressed.
1. It can be inferred from the passage that one of the reasons why earlier scientists couldnt explain the status of nitrogen fixation among non-leguminious crops was that
A. scientists who were conducting experiments to study nitrogen fixation among non-leguminous crops confused cause with effect.
B. The scientists knowledge that the production of artificial nitrogen utilizes alarming quantities of natural resources, was incomplete.
C. In the first half of twentieth century researchers who sought to study why non-leguminous crops could not do nitrogen fixation, had to work with primitive equipment.
D. Unlike leguminous crops such as cleavers or soya beans, non-leguminous crops were not common in earlier days.
E. The staple diet of people in earlier days did not contain non-leguminous products.
2. The emphasis on research on nitrogen fixation since 1960 can be attributed to which of the following?
A. Nitrogen fixing plants are abundantly available.
B. The energy harvested by symbiosis is usually large.
C. Production of artificial nitrogen utilises large quantities of natural resources.
D. Productivity of crops was on the decline.
E. Previously it was felt that non-leguminous plants could maintain a symbiotic relationship with bacteria.
3. Which of the following is/are possibilities explored by scientists in order to introduce nitrogen fixation in non-leguminous crops?
I. Transplantation of genes from nitrogen fixing bacteria into the cells of non-leguminous plants.
II. Encouraging bacteria naturally available around plant roots become efficient in fixation of nitrogen.
III. Reducing nodule formation in the roots of non-leguminous plants.
A. I and III only B. II only C. I only
D. III only E. I and II only
Ans.
1-c
2-c
3-e
