A student investigated how the amount of protein in a person's diet affects the amount of urea produced. The mass of protein eaten each day and the mass of ...
Question 1 Report
A student investigated how the amount of protein in a person's diet affects the amount of urea produced. The mass of protein eaten each day and the mass of urea excreted each day were measured for one person on a low protein diet and again on a high protein diet. The table shows these results, and the diagram shows how urea is made in the body.
| Diet | Protein intake / g per day | Urea excreted / g per day |
|---|---|---|
| Low protein | 40 | 18 |
| High protein | 120 | 42 |
(a) Name the organ in which urea is made. [1]
(b) Name the process by which the amino group is removed from excess amino acids. [1]
(c) Using the table, calculate the percentage increase in the mass of urea excreted when the person changes from the low protein to the high protein diet. Show your working. [2]
(d) Explain why eating more protein increases the amount of urea produced. [3]
(e) Name the organ that removes urea from the blood and the tube that carries the urine it makes to the bladder. [2]
(f) Explain why urea must be removed from the body. [3]
Answer Details
This question tests protein metabolism and excretion of urea.
(a) Organ that makes urea. [1] The liver [1].
(b) Process removing the amino group. [1] Deamination [1].
(c) Percentage increase in urea. [2] Rise in urea \(=42-18=24\) g. As a percentage of the starting value: \[\frac{24}{18}\times100=\mathbf{133.3\%}\] [2: working 1, answer 1].
(d) Why more protein makes more urea. [3] Excess amino acids cannot be stored by the body [1]; they are deaminated and the amino group is converted to urea [1]; so eating more protein means more excess amino acids, and therefore more urea is made [1].
(e) Organ that removes urea and the tube to the bladder. [2] The kidney removes urea from the blood [1]; the ureter carries the urine to the bladder [1].
(f) Why urea must be removed. [3] Urea is toxic/poisonous [1]; if it built up it would damage cells/tissues [1]; so it must be excreted in the urine [1]. Exam tip: keep "ureter" (kidney to bladder) separate from "urethra" (bladder to outside).
Download The App On Google Playstore
Everything you need to excel in your exams
