Topic 13.1.2: Deamination

Limitless IGCSE Biology Exam - Biochemistry Focus

Section A: Multiple Choice (Paper 2)

1. Where in the body does deamination occur?

A) KidneyB) LiverC) PancreasD) Small intestine

2. Which type of molecule is broken down during deamination?

A) Fatty acidsB) GlucoseC) Amino acidsD) Glycerol

3. What is removed from an amino acid during deamination?

A) Amino group (-NH₂)B) Carboxyl group (-COOH)C) Hydrogen atomsD) Carbon skeleton

4. Why must urea be excreted from the body?

A) It contains useful energyB) It is needed for growthC) It helps with digestionD) Ammonia (from which it forms) is toxic

5. What is meant by the term "assimilation" of amino acids?

A) Absorption from the small intestineB) Building absorbed amino acids into proteins needed by the bodyC) Breaking down proteins into amino acidsD) Removing the amino group

Section B: Theory (Paper 4)

6. Define the term "deamination". [3 marks]

7. Explain why ammonia must be converted to urea. [2 marks]

8. Explain why excess amino acids from the diet must be broken down. [3 marks]

9. Define the term "assimilation" in relation to amino acids. [2 marks]

10. Describe the roles of the liver and kidney in removing urea from the body. [3 marks]

Section C: Data Analysis (Paper 6)

Context: A student investigated the relationship between protein intake and urea concentration in urine. They measured urea concentration after consuming different amounts of protein over several weeks.

11. What would you expect to happen to urea concentration in urine as protein intake increases?

A) Decrease steadilyB) Stay the sameC) Increase steadilyD) Increase then decrease

12. Identify the independent and dependent variables in this investigation. [2 marks]

13. State TWO variables that should be controlled in this investigation. [2 marks]

14. Explain why increased protein intake leads to increased urea concentration in urine. [2 marks]

15. Describe how you would display this data on a graph. Include details of axes and type of graph. [3 marks]

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