Proteobacteria Week12

Which of the following is NOT Gammaproteobacteria?

• Azotobacter

• Escherichia

• Rhizobium

• Vibrio

_________________ the first aerobic free-living nitrogen fixer

• Azotobacter agilis

• Azotobacter chroococcum

• Rhizobium eteli

• Rhizobium galegae

the conversion of nitrogen to ammonia or nitrogenous compounds is called

• Nitrogen assimilation

• Nitrogen fixation

• Denitrification

• Nitrification

Which of the following nitrogen fixer is involved in the symbiotic association with legumes forming root nodules?

• Rhizobium

• Azotobacter

• Rhodospirillum

• Clostridium

How does a legume plant benefit from Rhizobia living within the legume root nodules?

• Rhizobia fix atmospheric nitrogen and convert it into ammonia that can be used by the plant

• Rhizobia protect legumes from pathogenic organisms.

• Rhizobia supply carbon compounds (sucrose) to the legume plant

• Rhizobia supply fats to the legume plant

Biological nitrogen fixation:

• allows legumes to more efficiently use water

• is energetically costly to legumes

• enhances photosynthesis in legumes

• is of no benefit to the plant; it’s just a biological curiosity

The relationship between leguminous plants and Rhizobia bacteria is best described as:

• associative

• autotrophic

• interspecific competition

• symbiotic

Which of the following is the colony morphology of Rhizobium on CRYEMA agar plate?

• The colonies were circular, creamy white, raised and smooth

• Rhizobium utilize congo red dye very slowly and formed white, circular and raised colonies

• Rhizobium does not utilize congo red dye and formed red, circular and raised colonies

• Rhizobium cannot grow on CRYEMA agar plate

Leghemoglobin creates

• condition for optimum activity of nitrogenase

• high oxygen concentration for nitrogen fixation by Rhizobia

• Required oxygen concentration for optimum activity of nitrogenase

• Suitable environment for nodule formation

All of the following Vibrio sp. are halophilic, except:

• Vibrio cholerae

• Vibrio parahaemolyticus

• Vibrio alginolyticus

• Vibrio vulnificus