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

It can be concluded from the figure that

#Question id: 11112

#Unit 7. System Physiology – Animal

The respiratory movement representing the total amount of exchangeable air is the:

#Question id: 11111

#Unit 7. System Physiology – Animal

Hypoventilation dramatically increases carbonic acid concentration and involves:

#Question id: 11089

#Unit 7. System Physiology – Animal

A 45-year-old man inhaled as much air as possible and then expired with a maximum effort until no more air could be expired. This produced the maximum expiratory flow-volume curve shown in the following diagram. What is the forced vital capacity of this man (in liters)?

#Question id: 11088

#Unit 7. System Physiology – Animal

At a fraternity party a 17-year-old male places a paper bag over his mouth and breathes in and out of the bag. As he continues to breathe into this bag, his rate of breathing continues to increase. Which of the following is responsible for the increased ventilation?

#Question id: 11087

#Unit 7. System Physiology – Animal

Which of the following oxygen-hemoglobin dissociation curves corresponds to normal blood (red line) and blood containing carbon monoxide (green line)?

#Question id: 11086

#Unit 7. System Physiology – Animal

A 17-year-old female was bicycling without a helmet when she fell and hit her head. In the emergency room, she was not conscious and was receiving ventilator assistance. Her blood gases follow:

PaO2 = 52 mm Hg,

PaCO2 = 75 mm Hg, pH = 7.15, and

HCO3− = 31 mM

The majority of the CO2 was being transported as