AP BIOLOGY

Detailed explanation-1: -Rhizobium is symbiotic nitrogen fixer bacteria which is found in root nodules of leguminous plants. Azotobacter is a non-symbiotic nitrogen fixer bacteria. So, the correct option is ‘False’.

Detailed explanation-2: -All plants under cultivation, except legumes (plants with seed pods that split in half, such as lentils, beans, peas or peanuts) get the nitrogen they require through the soil. Legumes get nitrogen through fixation that occurs in their root nodules, as described above.

Detailed explanation-3: -Rhizobium is a nitrogen-fixing bacteria found in the root nodules of pulses like peas, green gram etc. The bacteria fix atmospheric nitrogen and provide it to the plants to absorb. In return, the plants provide shelter and nutrition to the bacteria.

Detailed explanation-4: -The bacteria live inside the root nodules where they trade nutrients with the plants. The bacteria provide nitrogen and the plant provides sugars from photosynthesis. Not all plants can make nodules, so this type of symbiosis is restricted to only certain plants.

Detailed explanation-5: -Rhizobium bacteria fix nitrogen and make it available to plants. However, they are not present in all plants. Some special plants such as peas and legumes contain these bacteria in special structures of their roots.