Excretion Exam Corrections

Question 1

Suggest why ornithine and ammonia and CO2 require ATP to move out of the mitochondria

Answer 1

Mitochondria produces ATP which allows active transport of molecules against the concentration gradient
- molecules need to move out of the mitochondria faster than diffusion would allow

Question 2

Deduce why and how catalase is regulated inside the liver cells.

Answer 2

Large quantities of H2O2 produces lots of O2 very quickly
Isolation of catalase in peroxisomes
Cells have no control over temp and substrate concentration so enzyme concentration has to be controlled
Limit enzyme concentration by regulating the expression of the enzyme (transcription factors )

Question 3

Where does deamination occur

Answer 3

In the liver

Question 4

When old red blood cells are broken down, each harm group is converted to bilirubin which passes through the digestive system. Explain why bilirubin production and processing is an example of secretion.

Answer 4

Bilirubin produced from harm is metabolic waste
So is removed from the body

Question 5

Explain how hepatocytes are adapted to carry out their function

Answer 5

Thin cell walls provide a short diffusion distance

Question 6

Compare processes in the PCT and DCT

Answer 6

Similarities:
Both use active transport
Both involve Co transport
Both involve selective reabsorption
Both involve the use of sodium ions
Differences:
DCT involves the use of Ca2+
Co transport in DCT involves ions only
PCT involves ions and molecules ( glucose)

Question 7

How can the overall fitness of a patient affect the kidney function?

Answer 7

Alters the metabolism of creatine from creatine phosphate

Question 8

Explain why some food affect urine production.

Answer 8

Lactose and bread increases the water potential of the blood
Osmoreceptors detect this increase in the blood and secrete less ADH. Less aquaporins in the collecting duct induced so less selective reabsorbtion of water down WP gradient by osmosis so higher rate or urine produced

Salted crisps and boiled sweets have lots of salt and ions which means more salts are reabsorbed in the blood reducing water potential in the blood and increasing the water potential gradient so water moves in by osmosis.

Question 9

Explain why veins are visible in bodybuilders sometimes

Answer 9

Veins have thin walls so bulge / distend
They are close to the surface area
Wide lumen in the veins