Topic 6 EXAM QUESTIONS 6.4 (homeostasis)

Question 1

Using your knowledge of the kidney, explain why glucose is found in the
urine of a person with untreated diabetes. (3)

Answer 1

1. High concentration of glucose in blood/filtrate;
   Accept tubule for filtrate.
2. Not all the glucose is (re)absorbed at the proximal convoluted tubule;
   Reject no glucose is (re)absorbed.
3. Carrier/co-transport proteins are working at maximum rate
   OR
   Carrier/co-transport proteins/ are saturated;

Question 2

Describe the role of glucagon in gluconeogenesis.
Do not include in your answer details on the second messenger model of
glucagon action. (2)

Answer 2

1. (Attaches to receptors on target cells and) activates/stimulates
   enzymes;
   Reject ‘produces enzymes’.
2. Glycerol/amino acids/fatty acids into glucose;

Question 3

Explain how inhibiting adenylate cyclase may help to lower the blood
glucose concentration. (3)

Answer 3

. Less/no ATP is converted to cyclic AMP/cAMP;
2. Less/no kinase is activated;
3. Less/no glycogen is converted to glucose
OR
Less/no glycogenolysis

Question 4

Alport syndrome (AS) is an inherited disorder that affects kidney glomeruli of
both men and women. Affected individuals have proteinuria (high quantities of
protein in their urine).
(a) Suggest how AS could cause proteinuria.
(2)

Answer 4

1. Affects/damages basement membrane
   OR
   More protein channels/carriers in basement membrane;
2. Proteins can pass into the (glomerular) filtrate/tubule;

Question 5

Describe how ultrafiltration occurs in a glomerulus (3)

Answer 5

1. High blood/hydrostatic pressure;
   Ignore references to afferent and efferent arterioles
   Ignore ‘increasing/higher blood pressure’ as does not
   necessarily mean high
2. Two named small substances pass out eg water, glucose,
   ions, urea;
   Accept correct named ions
   Accept mineral ions/minerals
   Accept amino acids/small proteins
   Ignore references to molecules not filtered
3. (Through small) gaps/pores/fenestrations in (capillary)
   endothelium;
   Accept epithelium for endothelium
4. (And) through (capillary) basement membrane;

Question 6

Furosemide inhibits the absorption of sodium and chloride ions from the
filtrate produced in the nephrons.
Explain how furosemide causes an increase in the volume of urine
produced. (3)

Answer 6

1. Water potential of filtrate/tubule decreased;
   Accept correct reference to water potential gradient
   Accept maintains low water potential.
   Accept nephron for filtrate/tubule.
2. Less water (reabsorbed) by osmosis (from filtrate/tubule);
   Accept nephron for filtrate/tubule.
   Accept no water (reabsorbed) for ‘less’
   Accept (more) water (absorbed) by osmosis (into
   filtrate/tubule)
3. Collecting duct (is where osmosis occurs);