Problem Set Unit The base ratios in the DNA and RNA for an onion (Allium cepa) are given below.

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1 Problem Set Unit 3 Name 1. Which molecule is found in both DNA and RNA? A. Ribose B. Uracil C. Phosphate D. Amino acid 2. Which molecules form the nucleotide marked in the diagram? A. phosphate, deoxyribose and nitrogenous base B. phosphorus, ribose and nitrogenous base C. phosphorus, deoxyribose and guanosine D. phosphate, ribose and guanine 3. The base ratios in the DNA and RNA for an onion (Allium cepa) are given below. Bases A / % G / % C / % T / % DNA Bases A / % G / % C / % U / % RNA What is the reason for the difference between these figures? A. DNA is only found in the nucleus but RNA is found throughout the cell. B. DNA is made entirely of double helix but RNA is not. C. In DNA, bases A and T are complementary but in RNA, bases A and C are complementary. D. RNA comes in three forms but DNA only comes in one form. IB Questionbank Biology 1

2 4. In the model of the DNA molecule shown below, which arrows point to covalent bonds? A. I, II and III only B. II, III and IV only C. I, III and IV only D. I, II and IV only 5. The percentage of thymine in the DNA of an organism is approximately 30%. What is the percentage of guanine? A. 70% B. 30% C. 40% D. 20% 6. What does a nucleosome consist of? A. DNA and histones B. DNA and chromatin C. Chromatin and nucleotides D. Mature RNA and histones 7. Which events occur during the G 1 phase and S phase of the cell cycle? G 1 phase S phase A. DNA replicates cell grows B. mitosis begins cell divides C. cell divides mitosis begins D. cell grows DNA replicates IB Questionbank Biology 2

3 8. What happens during the G 2 stage of interphase? A. Homologous chromosomes pair B. Synthesis of proteins C. Homologous chromosomes separate D. Replication of DNA 9. What is the sequence of stages during the cell cycle? A. G 1 S G 2 mitosis cytokinesis B. mitosis G 1 G 2 cytokinesis S C. G 1 G 2 S mitosis cytokinesis D. G 1 G 2 mitosis cytokinesis S 10. The diagram below shows a cell during mitosis. What are the structures and stage of mitosis? Stage of mitosis Structure I Structure II A. metaphase chromatid nuclear membrane B. anaphase centromere plasma membrane C. anaphase chromatid nuclear membrane D. metaphase centromere plasma membrane 11. Which of these processes require mitosis? A. Embryological development B. Reducing surface area to volume ratio C. Maintaining cell size D. Cell growth 12. Which of the following does not occur during interphase? A. Replication B. Translation C. Cytokinesis D. An increase in the number of mitochondria IB Questionbank Biology 3

4 13. Which enzyme catalyzes the elongation of the leading strand? [Source: image from W K Purves, et al., (2003) Life: The Science of Biology, 4, Sinauer Associates ( and W H Freeman ( A. RNA polymerase B. Helicase C. DNA polymerase D. Ligase 14. What is the reason for Okazaki fragments being formed during DNA replication? A. To enable replication of the 3 5 (lagging) strand B. To form the template for the RNA primers C. To initiate replication on the 5 3 (leading) strand D. To help the DNA helicase unwinding the DNA helix 15. What is replicated by a semi-conservative process? A. Messenger RNA (mrna) only B. Messenger RNA (mrna) and transfer RNA (trna) only C. Messenger RNA (mrna), transfer RNA (trna) and DNA only D. DNA only 16. The diagram below shows part of a DNA molecule that is being replicated. Where would DNA polymerase link the next nucleotide during replication? A. I B. II C. III D. IV IB Questionbank Biology 4

5 17. Where does the RNA polymerase bind during the process of transcription? A. The polysome B. The operator C. The promoter D. The initiator 18. What is a codon? A. A sequence of nucleotides on rrna that corresponds to an amino acid B. A sequence of nucleotides on mrna that corresponds to an amino acid C. A sequence of nucleotides on trna that corresponds to an amino acid D. A sequence of nucleotides on DNA that corresponds to an amino acid 19. What enzyme is used in transcription but not in translation? A. DNA polymerase B. Helicase C. Protease D. RNA polymerase 20. A certain gene in a bacterium codes for a polypeptide that is 120 amino acids long. How many nucleotides are needed in the mrna to code for this polypeptide? A. 30 B. 40 C. 360 D What happens during translation? A. Copying of DNA to produce DNA B. Copying of DNA to produce mrna C. Copying of DNA to produce trna D. Polypeptide synthesis 22. What is the function of the trna activating enzyme? A. It links trna to ribosomes. B. It links trna to mrna. C. It links trna to a specific amino acid. D. It links an amino acid on one trna to an amino acid on another trna. IB Questionbank Biology 5

6 23. The table below shows the codons that determine different amino acids in protein translation. First base Second base in codon Third base in codon U C A G in codon U Phe Ser Tyr Cys U Phe Ser Tyr Cys C Leu Ser A Leu Ser Trp G C Leu Pro His Arg U Leu Pro His Arg C Leu Pro Gln Arg A Leu Pro Gln Arg G A Ile Thr Asn Ser U Ile Thr Asn Ser C Ile Thr Lys Arg A Met Thr Lys Arg G G Val Ala Asp Gly U Val Ala Asp Gly C Val Ala Glu Gly A Val Ala Glu Gly G What is the sequence of the amino acids that is being translated from the following mrna sequence? 5 AUGGGUGCUUAUUGGUAA 3 A. Met-Pro-Arg-Ile-Thr B. Met-Cys-Ser-Tyr-Trp C. Met-Gly-Ala-Tyr-Trp D. Met-Gly-Tyr-Ala-Thr 24. What sequence of processes is carried out by the structure labelled X during translation? A. Combining with an amino acid and then binding to an anticodon B. Binding to an anticodon and then combining with an amino acid C. Binding to a codon and then combining with an amino acid D. Combining with an amino acid and then binding to a codon IB Questionbank Biology 6

7 25. (a) State the type of bonds that (i) connect base pairs in a DNA molecule.... (ii) link DNA nucleotides into a single strand.... (b) Distinguish between DNA and RNA nucleotides by giving two differences in the chemical structure of the molecules..... (c) Explain the role of transfer RNA (trna) in the process of translation (Total 6 marks) 26. The diagram below shows one DNA nucleotide and part of a second nucleotide. (a) (b) (c) State the names of structures I and II. I.... II.... On the diagram above, draw the structures that are missing from the second nucleotide. The two nucleotides would be permanently separated during DNA replication. State one process during which they would be temporarily separated.. (d) Outline the method that can be used to amplify small quantities of DNA to obtain large enough quantities for DNA profiling..... (Total 5 marks) IB Questionbank Biology 7

8 27. The micrograph below shows an adult human stem cell. [ Science Photo Library. Used with permission.] (a) The cell cycle can be divided into two parts: interphase and mitosis. (i) Identify, with a reason, whether the stem cell in the micrograph is in interphase or mitosis (ii) Deduce two processes that occur in human cells during this part of the cell cycle, but not during the other part (b) State two characteristics of stem cells that can be used to distinguish them from other body cells (c) Outline one therapeutic use of stem cells (3) (Total 8 marks) 28. Up to two additional marks are available for the construction of your answers. (a) Most of the DNA of a human cell is contained in the nucleus. Distinguish between unique and highly repetitive sequences in nuclear DNA. (5) (b) Draw a labelled diagram to show four DNA nucleotides, each with a different base, linked together in two strands. (5) (c) Explain the methods and aims of DNA profiling. (8) (Total 20 marks) IB Questionbank Biology 8

9 29. Up to two additional marks are available for the construction of your answers. (a) Draw a labelled diagram to show how two nucleotides are joined together in a single strand of DNA. (3) (b) Outline a basic technique for gene transfer. (6) (c) Explain the process of translation. (9) (Total 20 marks) IB Questionbank Biology 9