#Question id: 9239
#Unit 9. Diversity of Life Forms
Why are changes in the global carbon cycle important?
#Question id: 26984
#Unit 10. Ecological Principles
#Question id: 5751
#Unit 8. Inheritance Biology
A biochemical mutant that must be supplied with a particular nutrient for growth would be described as a(n)
#Question id: 5415
#General Aptitude
The average marks of three batches of student having 70, 80 and 50 students respectively are 60 ,50 and 46 the average marks of all the 200 students tekan together is
#Question id: 12084
#Unit 10. Ecological Principles
In bottom sediments of lakes and streams, organic matter is broken down by heterotrophic microorganisms and ammonia is released. Under aerobic conditions, specialized bacteria convert ammonia to nitrate (nitrification). This nitrate, together with nitrate from other sources, diffuses into the deeper sediments, where it may undergo anaerobic conversion to nitrogen gas (denitrification). These sediments typically contain oligochaete worms that live with their heads buried and their tails waving back and forth in the overlying water. Plastic columns were packed with freshly collected stream sediments and then covered with layers of nitrate enriched water. A similar set of columns was packed with sediment that had been sterilized and then covered with either nitrate-enriched water or distilled water. Oligochaete worms were collected and acclimated to 20°(C)Following acclimation, worms were rinsed in distilled water and then added to three sediment columns. The columns were incubated in the dark at 20°C and monitored every three days for changes in the concentration of nitrate in the overlying water. Nitrate concentrations in each of the experimental treatments were plotted against time, as shown in the graph below.
The best explanation for the increase in nitrate concentration in one treatment is that