Biomolecules quiz

Which of the following is the most abundant protein in the whole biosphere?

The bond that links two amino acids is a:

Which of these is a purine?

Inulin is a polymer of:

Which of the following is a secondary metabolite?

The R group of glycine is:

Enzymes that catalyse the removal of groups from substrates by mechanisms other than hydrolysis, leaving double bonds, are:

Which of these is a phospholipid found in the cell membrane?

The coenzyme NAD contains the vitamin:

Malonate inhibits succinic dehydrogenase by:

How is the acid-soluble pool separated from the acid-insoluble fraction? (2 marks)

Why are lipids not true macromolecules but are found in the acid-insoluble fraction? (2 marks)

Why does starch give a blue colour with iodine but cellulose does not? (2 marks)

What are essential and non-essential amino acids? (2 marks)

What is meant by the primary structure of a protein? (2 marks)

What is the active site of an enzyme? (2 marks)

Why does enzyme activity decrease at high temperature? (2 marks)

What is the role of zinc in carboxypeptidase? (2 marks)

Name two functions of proteins in the body with examples. (2 marks)

What is chitin? Where is it found? (2 marks)

A triglyceride is formed from one glycerol and three fatty acids. How many ester bonds form and how many water molecules are released? If palmitic acid has 16 carbon atoms, how many carbon atoms are in tripalmitin (glycerol has 3 carbons)? (3 marks)

A DNA sample has 30% guanine. Calculate the percentage of adenine. If the molecule has 10,000 bases in all, how many of them are thymine? (3 marks)

A protein of 4 polypeptide chains has 141, 146, 141 and 146 amino acids. Calculate the total number of amino acids and peptide bonds. Name this protein and its level of structure. (3 marks)

An enzyme has its optimum temperature at 37 degrees C, where it works at 4 micromoles per minute. If the rate halves for every 10 degrees C above the optimum (illustrative), calculate the rate at 57 degrees C. (3 marks)

A DNA molecule makes 150 complete turns. Calculate the number of base pairs and its length in nm (10 bp per turn, 0.34 nm per bp). (3 marks)

Read the passage and answer the questions. To analyse the chemical composition of a living tissue, the tissue is ground in trichloroacetic acid using a mortar and pestle to obtain a thick slurry. When this is strained through cheesecloth, two fractions are obtained: the filtrate or acid-soluble pool, and the retentate or acid-insoluble fraction. (i) What molecules are present in the acid-soluble pool? (ii) Why are these molecules called micromolecules? (iii) Name the macromolecules present in the acid-insoluble fraction. (5 marks)

Read the passage and answer the questions. Proteins are polypeptides. They are linear chains of amino acids linked by peptide bonds. Each protein is a polymer of amino acids. As there are 20 types of amino acids, a protein is a heteropolymer. Dietary proteins are the source of essential amino acids. (i) Why is a protein a heteropolymer? (ii) What are essential amino acids? (iii) Give two functions of proteins with examples. (5 marks)

Read the passage and answer the questions. Almost all enzymes are proteins. There are some nucleic acids that behave like enzymes, called ribozymes. An enzyme, like any protein, has a primary structure. The protein chain is folded upon itself, and within this backbone it creates crevices or pockets called active sites into which the substrate fits. (i) What is a ribozyme? (ii) What is the active site? (iii) How is enzyme catalysis different from inorganic catalysis? (5 marks)

Read the passage and answer the questions. The activity of an enzyme can be affected by a change in the conditions which can alter the tertiary structure of the protein. These include temperature, pH, change in substrate concentration, or binding of specific chemicals that regulate its activity. Each enzyme shows its highest activity at a particular temperature and pH called the optimum. (i) What happens to enzymes at low temperatures? (ii) Why does enzyme activity level off at high substrate concentration? (iii) How does a competitive inhibitor work? (5 marks)

Read the passage and answer the questions. Nucleic acids are polynucleotides. Together with polysaccharides and polypeptides, they make up the true macromolecular fraction of any living tissue. A nucleotide has three chemically distinct components: a heterocyclic compound, a monosaccharide and a phosphoric acid or phosphate. (i) Name the heterocyclic compounds present in nucleic acids. (ii) What is the sugar in RNA and in DNA? (iii) Name the bond that links nucleotides. (5 marks)

How is the chemical composition of living tissues analysed? Compare the elemental composition of living and non-living matter. Explain primary and secondary metabolites with examples. (6 marks)

Describe the structure of amino acids, lipids and nucleotides with labelled diagrams. (6 marks)

Describe the structure of polysaccharides with examples. Why do starch and cellulose behave differently? Explain the structure of DNA. (6 marks)

What are enzymes? Explain their nature, mechanism of action and classification into six classes with examples. (6 marks)

Explain the factors affecting enzyme activity with graphs. Describe the types of cofactors with examples. (6 marks)