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# unit 2 bio help

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1. can someone pls explain what a barr body is in details .... is it present due to a genetic disease or is it meant to be present in all females????

pls answer asap my exam is in a couple of hours
thanks
2. A Barr body is a normal occurance in a female. Basically it is one of the X chromosomes being silenced to prevent over expression of proteins encoded by genes found there.
3. I'm glad you managed to see this before your exam. Best of luck.
4. Someone please help me on question 4c please http://filestore.aqa.org.uk/subjects...2-QP-JUN14.PDF
5. (Original post by maggie43)
Someone please help me on question 4c please http://filestore.aqa.org.uk/subjects...2-QP-JUN14.PDF
90 cm3 per kg per hour is the oxygen demand.

The mass of fish is 0.4 kg, reducing the oxygen demand to 90 x 0.4 = 36 cm3 per hour

The volume of oxygen absorbed per dm3 of water is 7 cm3.

This means 36/7 = 5.14 dm3 of water needed to supply this (per hour)
6. (Original post by bioevangelist)
90 cm3 per kg per hour is the oxygen demand.

The mass of fish is 0.4 kg, reducing the oxygen demand to 90 x 0.4 = 36 cm3 per hour

The volume of oxygen absorbed per dm3 of water is 7 cm3.

This means 36/7 = 5.14 dm3 of water needed to supply this (per hour)
And for the last bit. Increasing temperature reduces the solubility of gases in water. The higher the temperature the less oxygen dissolves in water. This means more water would need to flow over the gills to supply the same amount of oxygen to the fish.
7. (Original post by alkyone)
I'm glad you managed to see this before your exam. Best of luck.
hahah thanks

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