B12 Crit

Question 1

Explain the importance of kidneys in homeostasis

Answer 1

Kidneys remove urea and other toxins so levels do not build up and
poison cells,
and balance levels of water and mineral ions in body fluids to prevent
osmotic damage to cells

Question 2

Give 2 advantages and disadvantages of a kidney transplant instead of a dialysis machine

Answer 2

• no need for regular dialysis, no need for controlled diet, can live normal
  life.
• Have to take immunosuppressant drugs for life, may reject kidney,
  limited transplant lifespan.

Question 3

Explain why controlling the conditions in your body is important

Answer 3

• Optimal cell function requires correct temperature so enzymes work
  optimally,
• Correct concentration of water and mineral ions in blood so osmosis
  doesn’t cause cell damage,
• Glucose for respiration to provide ATP,
• Removal of waste products as build-up can change pH or poison
  systems

Question 4

Why do more people die when conditions are hot?

[5 (FIVE??) marks]

Answer 4

“people lose lots of water by sweating, become dehydrated and can’t
sweat more to cool down; exercise in high temperatures causes heating
from respiration in muscles; temperature regulation less efficient in
small children and the elderly; high humidity prevents cooling by
sweating, increasing body temperature”

better safe than sorry

Question 5

Explain two biological reasons why most doctors think that a kidney transplant is a
better method of treatment than dialysis.
Do not refer to cost or convenience.

Answer 5

changes in concentrations /
levels of substances / urea
are minimised
(so) less / no chance of causing
damage to body cells / tissues
not repeatedly puncturing skin

or blood not in contact with
machine
(so) less / no chance of infection
or less / no chance of blood
clots
or no need to take anti-clotting
drugs