Bill is a marathoner and is half way through the new york marathon. his legs (and some other muscles) are burning huge amounts of atp (total metabolic rate has increased to around 7 times basal). his cardiac output has risen to five times the basal rate. his respiratory rate has increased from 10 breath/min at rest to about 20 breath/min. his tidal volume has risen from 700 ml at rest to about 1525 ml. he weighs about 70 kg (~150 lb). if no other control actions or reflexes occur, what will be the effect on po2 at the alveoli:

a. increased by 30 mmhg,
b. largely unchanged,
c. decreased by 30 mmhg

explanation:

b,bacteria convert nitrates

into nitrogen gas.

d,plants and animals take in

and use nitrogen compounds.

e,bacteria break down waste    

products and return nitrogen  

to the soil.

a,bacteria convert atmospheric

nitrogen to ammonia.

c,bacteria convert ammonia

to nitrites and nitrates.

what are the options? add them, then i will be glad to .

the law of original horizontality explains:   why rocks appear in layers. correct answer: b the law suggests that all rock layers are originally laid down (deposited) horizontally and can later be deformed.   the principle is used by geologists to make assumptions about the relative ages of sedimentary rocks.