Oxygen Consumption in a CLOSED System

Question 1

T/F a closed system requires an air-tight container

Answer 1

true. there is no air flow. you measure the pressure difference between the container and the atmospheric pressure.

Question 2

How do you measure O2 intake of an animal in a closed system

Answer 2

you measure the pressure difference between the container and the atmospheric pressure.

Question 3

What two chemicals are needed in the closed system in order to measure solely O2 intake? How does this entire process work?

Answer 3

1) soda lime to absorb CO2
2) dessicant to absorb water vapour

• when the animal CONSUMES O2 inside the container and produces CO2, the CO2 gets absorbed by the soda lime. Thus, air/gas is literally taken up by the system itself, and the overall pressure inside the container drops BELOW atmospheric pressure. Therefor, PO2 initial>PO2 final.

If pressure isn’t being measured, the manometer instead moves its fluid up the tube, and you can measure the ml of O2 consumed by the amount of water used to recalibrate the manometer.

Question 4

Explain the relationship between temperature and the animal’s specific metabolic rate (o2 consumption per gram) for a mouse and for a fish

Answer 4

a mouse= endotherm
fish = ectotherm

There is an INVERSE relationship between endotherm and ectotherm.

As temp in environment increases for the mouse, O2 consumption goes down (endotherm). That’s because he’s working to maintain a certain body temperature. He maintains his body temp by fueling his body by being active and generate the heat of his activity that keeps his body temperature constant. He is using the products of metabolism to produce heat. Hot = decrease metabolism in endotherms.

Reverse for the fish: O2 consumption goes up as temp goes up. Temp of body varies with ambient (environmental) temperature. O2 consumption goes up because enzyme kinetics and chemical reactions are speeding up. More ATP is required to facilitate this, and O2 is thus needed.

Question 5

T/F: ectotherms have more mitochondria than endotherms

Answer 5

false. endotherms tend to have more mitochondria in their tissues than ectotherms in order to maintain temperature through metabolic processes.