13. Excretion in humans
A section of Biology, 0610
Listing 10 of 267 questions
For Examiner's Use State three uses of water in the human body. In the human body, the amounts of different substances, such as water, remain within narrow limits. Name the term used to describe the maintenance of a constant internal environment. shows the water gains and losses in a human over 24 hours. daily water gains drinks water in food water formed within body total 1500 cm3 700 cm3 200 cm3 2400 cm3 daily water losses exhaled air faeces sweat urine total 400 cm3 100 cm3 500 cm3 ? cm3 2400 cm3 shows that water is formed within the body. Name a reaction in the body that produces water. Use to calculate the volume of water the person must lose in their urine over the 24 hours to keep the volume of water in the body constant. volume of water lost in urine cm3 For Examiner's Use The kidney excretes excess water. State three other processes that occur in the kidney. On a very hot day the volume of water lost as sweat may increase. Suggest how increased sweating could affect the urine a person produces.
0610_s13_qp_22
THEORY
2013
Paper 2, Variant 2
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For Examiner's Use The kidneys remove metabolic waste from the liquid part of the blood. Name: the liquid part of the blood; the process that involves removing metabolic waste from the body. shows a kidney tubule and its associated blood vessels. X Y B Z A Describe the functions of the regions labelled A and B. A B For Examiner's Use Table 1.1 shows the concentrations of some substances in the blood at X, the fluid at Y and the urine at Z. Table 1.1 concentration / g per 100 cm3 substance blood at X fluid at Y urine at Z glucose 0.1 0.1 0.0 protein sodium ions 0.35 0.35 0.5 urea 0.03 0.03 2.0 Name the substance shown in Table 1.1 that: has molecules that are too large to pass through the walls of capillaries; is all reabsorbed in the kidney; is a metabolic waste product. Explain why the concentrations of sodium ions and urea are greater at Z than at Y. For Examiner's Use People who have acute kidney failure are given dialysis treatment. In dialysis machines, the blood flows through narrow tubes made from partially permeable membranes, surrounded by dialysis fluid. Dialysis fluid contains sodium ions. Use the information in Table 1.1 to suggest the concentration of sodium ions that should be in the fluid and give a reason for your answer. concentration g per 100 cm3 reason State two components of blood that are not in dialysis fluid. Heparin is added to the blood before it returns to the body from the dialysis machine. Heparin prevents a person’s blood from clotting. Describe the process of blood clotting.
0610_s13_qp_32
THEORY
2013
Paper 3, Variant 2
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Questions Discovered
267