IBDP Official Exam Material
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Option B: Biochemistry
For HL students only
1a. [2 marks]
Aspartame is formed from the two amino acids aspartic acid (Asp) and phenylalanine (Phe).
Draw the structure of the dipeptide A
1b. [3 marks]
Chromatography is used in the analysis of proteins in the food and pharmaceutical industry.
Describe, using another method, how a mixture of four amino acids, alanine, arginine, glutamic acid and glycine, could be separated when placed in a buffer solution of pH 6.0.
1c. [1 mark]
Suggest why alanine and glycine separate slightly at pH 6.5.
1d. [1 mark]
Calculate the ratio of [A−] : [HA] in a buffer of pH 6.0 given that pKa for the acid is 4.83, using section 1 of the data booklet.
2a. [1 mark]
The Michaelis–Menten equation describes the kinetics of enzyme-catalysed reactions.
Outline the significance of the Michaelis constant Km.
3. [1 mark]
Stearic acid (Mr = 284.47) and oleic acid (Mr = 282.46) have the same number of carbon atoms. The structures of both lipids are shown in section 34 of the data booklet.
The iodine number is the number of grams of iodine which reacts with 100 g of fat. Calculate the iodine number of oleic acid.
4a. [1 mark]
DNA, deoxyribonucleic acid, is made up of nucleotides.
List two components of nucleotides.
4b. [2 marks]
Explain how the double-helical structure of DNA is stabilized once formed.
5a. [2 marks]
Changes in physiology can impact living creatures.
The graph shows the change in oxygen partial pressure in blood, measured at different pH values.
Explain the effect of changing pH on the percentage saturation of hemoglobin at a given partial pressure of oxygen.
5b. [2 marks]
Explain the biomagnification of the pesticide DDT.
5c. [1 mark]
Vitamins are organic compounds essential in small amounts.
State the name of one functional group common to all three vitamins shown in section 35 of the data booklet.
6a. [2 marks]
Describe the function of chlorophyll in photosynthesis.
6b. [2 marks]
Compare and contrast the structures of starch and cellulose.
One similarity:
One difference:
6c. [2 marks]
Explain why maltose, C12H22O11, is soluble in water.
7. [2 marks]
Ascorbic acid and retinol are two important vitamins.
Explain why ascorbic acid is soluble in water and retinol is not. Use section 35 of the data booklet.
8a. [1 mark]
New genetically modified organisms (GMO), especially plants, are continually being developed in research laboratories.
Outline what is meant by genetically modified organisms.
8b. [1 mark]
Outline one benefit of the use of these products.
9a. [1 mark]
Amino acids contain both acidic and basic functional groups.
An aqueous solution of glutamine contains 0.600 mol dm−3 of the zwitterion and 0.300 mol dm−3 of the anionic form.
pKa1 = 2.2 and pKa2 = 9.1
Outline which pKa value should be used when calculating the pH of the solution, giving your reason.
9b. [1 mark]
Calculate the pH of the glutamine solution using section 1 of the data booklet.
9c. [2 marks]
Describe what is meant by the genetic code and how it relates to protein synthesis.
10a. [1 mark]
Genetic information is stored in DNA.
State the feature of DNA that determines the primary structure of proteins synthesised by a cell.
10b. [1 mark]
Suggest one concern about the use of genetically modified, GM, food.
11a. [2 marks]
Enzymes are mainly globular proteins.
Describe the interaction responsible for the secondary structure of a protein.
11b. [3 marks]
Explain the action of an enzyme and state one of its limitations.
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