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DecimoNacional Name Student:

Biology

Exam I& II

10 Nal

1 hour30 minutes

Thursday 15 March 2012

INSTRUCTIONS TO CANDIDATES Do not open this examination paper until instructed to do so.Answer all the questions. For each question, choose the answer you consider to be the best and indicate your choice Answer all in the spaces provided. Use pen only. Use clear handwriting Paper I

Paper II

Paper I 1.Which structure is found in all prokaryotic cells? A. Flagella

Puntos Nota 19-20 7 17-18 6 15-16 5 12-14 4 8-11 3 3-7 2 1-2 1

Puntos Nota 35-40 7 30-34 6 26-29 5 20-25 4 11-19 3 6-10 2 1-5 1

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B. Ribosomes C. Mitochondria D. Vacuoles 2. During endocytosis, what change will most likely occur in the plasma membrane of a cell? A. It will form two phospholipid monolayers. B. It will become electrically charged. C. It will partially dissolve. D. It will form vesicles. 3. Which of the following could be a function of a membrane protein? A. Energy storage B. Enzymatic activity C. Oxygen uptake D. Thermal insulation 4. In which compounds would a double bond link carbon to oxygen (C=O)? I. Amino acid II. Fattyacid III. Glycerol A. I and II only B. II and III only C. I and III only D. I, II and III 5. Why is the genetic code described as degenerate? A. Some codons can cause translation to stop. B. More than one codon can represent one amino acid. C. The genetic code is the same in all organisms. D. Codons can change through mutation. 6. During the process of replication, which bond(s) in the diagram of DNA below is/are broken?

A. 3 B. 4, 5 C. 1, 2, 6, 7 D. 1, 7, 4, 5 7. What is the maximum number of fatty acids that can be condensed with glycerol? A. One B. Two C. Three D. Four 8. What is the correct order of increasing size for the following biological structures? I. The width of a virus II. The width of a bacterium

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III. The thickness of a cell surface membrane IV. The diameter of a eukaryotic cell A. I → III → II → IV B. I → III → IV → II C. III → I → II → IV D. III → II → I → IV 9. The diagram shows part of a molecule produced by replication of DNA. What is the significance of the shaded and the unshaded regions?

A. The shaded parts are DNA and the unshaded parts are mRNA. B. The shaded parts contain adenine and thymine and the unshaded parts contain guanine and cytosine. C. The shaded part is a codon and unshaded part is an anticodon. D. One of the parts has been newly synthesised and the other was part of a pre-existing DNA molecule. 10. If mRNA has a codon CAU, what is the corresponding anticodon on the tRNA molecule? A. CAT B. GUA C. CAU D. GTA 11. What are pyrimidines in DNA? A. Types of nucleotides B. Types of base pairs C. Types of sugars D. Types of bases 12. Which enzyme removes the RNA primer during replication? A. RNA primase B. DNA polymerase I C. DNA ligase D. Helicase 13. Which of the following structures are present in both plant and animal cells? I. Cell wall II. Chloroplast III. Mitochondrion A. I only B. I and II only C. I and III only D. III only 14. Which of the following is a feature of exocytosis but not endocytosis? A. Shape changes of a membrane B. Vesicle formation

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C. Use of ATP D. Secretion 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. If 15 % of a sample of DNA is thymine, what percentage of the DNA is guanine? A. 15 % B. 30 % C. 35 % D. It cannot be determined from the information given. 17. On which molecule is a codon found? A. Polypeptide B. mRNA C. tRNA D. rRNA 18. Which of these molecules is a disaccharide? A. Galactose B. Sucrose C. Cellulose D. Ribose 19. 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

20. Which molecule is shown below?

A. Glucose B. Galactose C. Ribose D. Sucrose

Paper II

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1. Outline the significance of the labeled parts of this diagram, showing the attraction between

three water molecules. [6]

w.

x.

y.

z.

δ-

δ+

2. Complete the table below: [6]

-saccharides examples Plant or animal? Function/ uses

Mono- animal

plant

Di-

plant

animal

Poly- animal

plant

3. Outline the relevance of the following properties of lipids. [3]

Energystorage

Thermalinsulation

Buoyancy

4. Label the structures of this single nucleotide. [3]

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a.

b.

c.

5. Complete the table below to show the pairings of the bases in DNA: [4]

Purine Pyramidine

6. Transcribe and translate this DNA sequence. [4]

DNA T A C G G G C C C G T G A C A G C C A C T mRNA Amino

acid

7. Deduce the amino acids translated from these mRNA codons, using the table. [6]

AUG =

CAG =

UCA =

GAC =

AAA =

UGA/UAG =

8. Identify the stage of mitosis shown in the following diagrams by completing the table below. [8]

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¡Enjoy the Science!