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## Homework help!

Debate and discussion of any biological questions not pertaining to a particular topic.

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### Homework help!

Hi all

Listed below are hemoglobin P50 values and blood O2 capacity in a number of different species.

Which animal has hemoglobin with the highest O2 affinity and which has hemoglobin with the lowest O2 affinity?

Animal P50 O2 capacity

Iguana 51 10.5
Rana (frog-lungs and skin) 39 8.1
Orcinus (whale) 34 21.5
Rabbit 32 15.6
Harbor seal 31 29.3
Sea otter 31 21.3
Alligator 28 6.7
Horse 26 16
Human fetus 20 8.4
Pseudemys (turtle) 19.5 8.7
Fetal goat 19 12
Dogfish 17 4.4
Mackerel 16 15.7
Necturus (salamander-gills) 15 6.3
Lumbricus (earthworm) 6.8 5.3
Carp 5 12.5
Chironomus (midge) 0.3 8.5

So i know that P50 is the P02 at which oxygen is 50% saturated...
and that then as P50 decreases, oxygen affinity increases, and vice versa.

However they are giving me a constant P50 and an O2 capacity value...

I can't seem to get what they what me to do... does the O2 capacity value mean the amount of O2 that is in the blood at the moment?

If so, then the greatest positive difference would be the animal with the greatest affinity for oxygen... so it would be the Iguana?
stupodity
Garter

Posts: 2
Joined: Wed Dec 08, 2010 3:13 am

Your understanding of P50 is OK
O2 capacity is defined here: http://www.biology-online.org/dictionar ... n_capacity
Units would be helpful, mostly for O2 capacity is it given per g of Hb or ml of blood?

As far as I understand P50 should be the way to measure the affinity and to compare it between species. I do not really see why they give you the capacity. And comparing both does not make much sense to me. Good luck
Patrick

Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)

canalon
Inland Taipan

Posts: 3909
Joined: Thu Feb 03, 2005 2:46 pm

### Re: Homework help!

Yeah i noticed that capacity does not affect affinity.

Thanks !!
stupodity
Garter

Posts: 2
Joined: Wed Dec 08, 2010 3:13 am