Assertion: Legume roots not colonized by Rhizobium do not synthesise leghemoglobin.
Reason: Some leguminous plants do not need nitrogen as an essential macronutrient.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but reason is false.
4. Both assertion and reason are false.

When nitrates are scarce in the soil where legumes are growing:
I. The plants secrete Nod factors that attract Rhizobia to their root hairs.
II. In turn the bacteria secrete flavonoids that stimulate the infection process in the plant.
1. Both I and II are correct
2. Only I is correct
3. Only II is correct
4. Both I and II are incorrect