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I- Multiple Choice questions. ( 10 marks) Choose the best answer 1. 2. 3. What type of bond holds the complementary base pairs together in a double helix of DNA? A. Covalent bonds B. Peptide bonds C. Glycosidic bonds D. Hydrogen bonds What are the components of a DNA nucleotide? A. Deoxyribose, a phosphate and one of the bases: adenine, cytosine, guanine or thymine B. Ribose, a phosphate and one of the bases: adenine, cytosine, guanine or uracil C. Deoxyribose, a nitrate and one of the bases: adenine, cytosine, guanine or thymine D. Ribose, a nitrate and one of the bases: adenine, cytosine, guanine or thymine The diagram below represents an animal cell. Which processes occur in the locations labeled? Transcription Translation Respiration A. II III I B. III II I C. II III IV D. III II IV 1 4. The diagram below represents DNA replication. Some of the bases are indicated. In which direction is the replication fork moving and which bases would be needed to replicate the section of DNA shown? 5. 6. Direction of movement of replication fork Bases needed A. Left to right U, G and C B. Right to left U, G and C C. Left to right T, G and C D. Right to left T, G and C What is responsible for the conservation of the base sequence during DNA replication? A. DNA polymerase working on one strand at the same time. B. Unpaired bases always attracting their complementary nucleotides. C. DNA helicase and polymerase are complementary. D. Both strands are identical to each other. Which substance is a base found in RNA? A. Ribose B. Thymine C. Adenosine D. Uracil 2 7. 8. 9. How would the following DNA sequence, ACGTTGCATGGCA, be transcribed? A. UGCAACGUACCGU B. TGCAACGTACCGT C. ACGTTGCATGGCA D. ACGUUGCAUGGCA 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. 480 What enzyme is used in transcription but not in translation? A. DNA polymerase B. Helicase C. Protease D. RNA polymerase 10. 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 11. If a person inherited an allele with the same base substitution mutation from both parents, what sequences could be altered from normal in the person’s cells? A. One mRNA base sequence only B. Two mRNA base sequences only C. One mRNA base sequence and one polypeptide amino acid sequence only D. Two mRNA base sequences and two polypeptide amino acid sequences only 3 II- Factual questions (8 marks) Answer all of the following. 1. The following diagram represents replication in DNA. A B [Freeman, Scott, Biological Science, 1st, 2002. Electronically reproduced by permission of Pearson Education, Inc., Upper Saddle River, New Jersey] (a) State the name and describe the function for the enzymes labelled A and B on the diagram. (i) (ii) A: B: Name: .......................................................................................... Function: .......................................................................................... Name: .......................................................................................... Function: .......................................................................................... (2) (b) Identify the cellular location of DNA replication in eukaryotic cells. .................................................................................................................................... (1) (c) State at which period during the cell cycle DNA replication occurs. .................................................................................................................................... (1) 4 (d) Explain the significance of complementary base pairing during DNA replication. .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... (2) (e) Outline the experiment done by Meselson and Stahl ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... (2) Extended response Questions (15 marks) Answer all of the following questions 1. Describe the consequence of a base substitution mutation with regards to sickle cell anaemia. (Total 7 marks) 2. Outline the process of translation. (Total 5 marks) 3. Describe the genetic code. (Total 4 marks) 5