The graph below shows the filtration, reabsorption, and excretion of glucose by the kidneys at different plasma glucose concentrations. Note that a healthy blood glucose concentration is around 100 mg 100 ml-1.
Which of the following is not a correct conclusion from the graph?
The maximum rate at which the kidneys can reabsorb glucose is 300 mg min-1.
Glucose in the urine can be normal for a healthy individual.
At plasma glucose concentrations higher than 300 mg 100 ml-1:
The graph below shows the effect of environmental temperature on water balance in kangaroo rats. Kangaroo rats are nocturnal, desert-living rodents that spend the daylight hours in underground burrows. Day-time temperatures in the underground burrows can reach 40 °C.
Which of the statements relating to kangaroo rats are correct?
I.
Kangaroo rats can survive in their natural habitat on a diet of seeds alone.
II.
Kangaroo rats are able to minimise water loss in urine due to their thick medullary region.
III.
Kangaroo rats lose less than 0.25 g day-1 of water in their faeces.
IV.
Oxidative phosphorylation is an important source of water for kangaroo rats.
Nephrogenic syndrome of inappropriate antidiuresis (NSIAD) is a rare condition that can be caused by a gain-of-function mutation in the gene that codes for ADH receptor proteins.
Which of the following will not be true for sufferers of NSIAD?
The kidney cells will respond to ADH even when ADH levels are low.
The body cells will swell up.
The kidney cells will have more water transport proteins in their cell surface membranes than normal.
The image below shows a test strip used for drugs testing. Unlike the hormone in a pregnancy test, the substances tested for in this kind of drugs test are too small to bind to more than one antibody at the same time. This type of test is known as a competitive binding assay.
The components of the test contain the following:
Conjugate pad - antibodies complementary to the drug being tested for. The antibodies are attached to a coloured bead.
Test line - bound molecules of the drug being tested for.
Control line - bound antibodies complementary to the antibody from the conjugate pad.
Which of the following correctly explains the appearance of a positive result?
The drug binds to antibodies on the conjugate pad, preventing them from binding to the test line.
The antibodies from the conjugate pad bind to the test line, causing the beads to form a visible band.
Unbound antibodies from the conjugate pad bind to antibodies on the control line, forming a visible band.
The drug binds to antibodies on the conjugate pad and to antibodies on the test line.
