Author: Kim Edgell
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Homeostasis-Osmoregulation
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Q1.The graph shows changes in the amounts of water, glucose and sodium ions as fluid passes along a kidney tubule from the renal capsule to the collecting duct
 
(a)     Which hormone causes the decrease in the water content in the distal convoluted tubule?
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(b)     Explain the change in the amount of glucose.
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(c)     Explain the shape of the curve for sodium ions in the loop of Henle.
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Q2.The graph below shows the concentration of the filtrate in different parts of one kidney tubule.
 
(a)     More than 99% of biological molecules are reabsorbed from the filtrate in the proximal convoluted tubule.Despite this, the concentration of fluid in this tubule remains constant.Explain why.
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(b)     Explain the shape of the curve in the loop of Henle in the graph.
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(c)     What is the evidence in the graph that this person was secreting antidiuretic hormone (ADH)?Explain your answer.
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Q3.(a)     The table shows the concentrations of dissolved substances in different regions of a nephron in a kidney in the presence and in the absence of antidiuretic hormone (ADH).
 
Region of nephron | Concentration of dissolved substances / arbitrary units
| ADH present | ADH absent
First convoluted tubule | 300 | 300
Bend of loop of Henle | 1000 | 1000
Start of second convoluted tubule | 150 | 150
Middle of second convoluted tubule | 250 | 90
Start of collecting duct | 300 | 50
End of collecting duct | 1000 | 50
Describe and explain the effect of ADH on the volume and concentration of urine produced by the kidney. Give evidence from the table to support your answer.
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(b)     Glomerulosclerosis is a disease in which the glomeruli of the kidney are damaged. Explain why protein is not normally present in the urine of a healthy person but may be present in the urine of a person with glomerulosclerosis.
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Q4.The kangaroo rat is a small desert mammal. It takes in very little water in its food and it rarely drinks. Its core body temperature is 38 °C.The kangaroo rat takes in some water by feeding and drinking. Describe another method by which the kangaroo rat could obtain water.
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Q5.
(a)     A diabetic person and a non-diabetic person each ate the same amount of glucose. One hour later, the glucose concentration in the blood of the diabetic person was higher than that of the non-diabetic person. Explain why.
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(b)     (i)     The urine of a non-diabetic person does not contain glucose. Explain why.
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(ii)     A high blood glucose concentration could cause glucose to be present in the urine of a diabetic person. Suggest how.
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(c)     A test for glucose in urine uses immobilised enzymes on a plastic test strip. One of these enzymes is glucose oxidase. Explain why the test strip detects glucose and no other substance.
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(d)     If the glomerular filtrate of a diabetic person contains a high concentration of glucose, he produces a larger volume of urine. Explain why.
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(e)     In some forms of kidney disease, proteins from the blood plasma are found in the urine. Which part of the nephron would have been damaged by the disease to cause proteins from blood plasma to be present in the urine? Explain your answer.
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