IGCSE Biology Paper-3: Specimen Questions with Answers 347 - 349 of 358

Passage

Excretion is the process of removing waste products of metabolism from the body.

Question 347 (4 of 7 Based on Passage)

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The liver is another excretory organ of the body. The liver breaks down hormones and drugs, such as alcohol.

(i) State one function of the liver other than the breakdown of hormones and drugs.

Explanation

  • Production of bile, which helps carry away waste and break down fats in the small intestine during digestion
  • Production of certain proteins for blood plasma
  • Conversion of excess glucose into glycogen for storage
  • Processing of hemoglobin for use of its iron content (the liver stores iron)
  • Regulating blood clotting

Question 348 (5 of 7 Based on Passage)

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The kidney is one of the main excretory organs of the body. Its role is to filter the blood. Some substances leave the blood and are removed from the body in the urine. The concentration of protein in the blood entering the kidneys in the renal arteries is 83 g dm – 3.

State the concentration of protein that you would expect in the urine of a healthy person and explain your answer.

concentration … g dm – 3

Explanation

Protein in Urine

Concentration

Diagram of Urine

Components of Urine

Urea and Creatinine

Question 349 (6 of 7 Based on Passage)

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Dialysis can be used to treat people whose kidneys do not function properly.

Fig. shows dialysis treatment.

Movement of Substance

Use Fig. to describe the process of dialysis and explain changes that occur in a person՚s blood.

Explanation

It is used to remove urea and creatinine. In such patients the blood is drained out through an artery into a ‘dialyzing unit’ after adding heparin, an anticoagulant. The dialyzing unit contains a coiled cellophane tube, surrounded by dialyzing fluid. This fluid has same composition as plasma except the nitrogenous wastes. The nitrogenous wastes from the blood pass through cellophane membrane into the dialyzing fluid and the blood is cleared of waste substances. The cleared blood, after addition of anti-heparin, is pumped back into the body through a vein.

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