LIFE SCIENCE

Detailed explanation-1: -The Rhizobium or Bradyrhizobium bacteria colonize the host plant’s root system and cause the roots to form nodules to house the bacteria (Figure 4). The bacteria then begin to fix the nitrogen required by the plant.

Detailed explanation-2: -The role of nitrogen-fixing bacteria is to provide plants with nutrients that they cannot acquire from the air. Nitrogen-fixing bacteria perform what crops cannot: they obtain assimilative N. Bacteria absorb it as a gas from the air and release it to the soil, typically as ammonia.