After leaving the cockroaches in their metabolic chamber for one hour, the gases in the chamber was measured. the fraction of oxygen in the chamber was 0.18. what was the metabolic rate of the cockroaches in ml o2/hr? (assume room air is 21% o2 and chamber volume=500ml)
a. 22.5
b. 0.135
c. 0.225
d. 13.5

The answer is 22.5ml

Explanation:

The chamber volume is 500 ml.

So amount of oxygen in chamber at the beginning

=

=105 ml

After the end of hour ; let x ml of oxygen was consumed.

Amount of oxygen at the end of 1 hour =18 %

So,

=0.18

Solving we get ;

105-x= 90-0.18 x

0.72 x =15                                      

x=20.83 ml

So amount of oxygen consumed in the hour =20.83 ml

So answer is A.

the two answers are a, the population of birds with large beaks will increase on the island, and c, the trait for large beaks will be passed on to future generations through natural selection. the reason for that is because if the birds that have beaks developed for eating small seeds lose all of their food, they will go hungry and eventually starve because they physically cannot eat the large seeds, therefore making the population of large beaked birds higher. also, if the trait of large beaks are dominant on the island over small beaks, then over time the large beaked birds will reproduce more and more, while the smaller beaked birds will reproduce less and less because they can't survive with the food provided. that leads to the trait of small beaks disappearing and the trait of large beaks taking over the island.