2017 RVHS H2 Biology Prelims Paper 1 Answers

River Valley High School Page 1 of 19 Year 6 H2 Biology 9744 Paper 1 2017 Preliminary Examination II RIVER VALLEY HIGH SCHOOL YEAR 6 PRELIMINARY EXAMINATION II CANDIDATE NAME CENTRE NUMBER S CLASS INDEX NUMBER H2 BIOLOGY 9744/01 Paper 1 Multiple Choice 22 Sep 2017 1 hour Additional Materials: Multiple Choice Answer Sheet READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Write your name, Centre number, index number on the Answer Sheet in the spaces provided unless this has been done for you. name in the spaces at the top of this page. DO NOT WRITE IN ANY BARCODES. There are thirty questions on this paper. Answer all questions. For each question there are four possible answers A, B, C, and D. Choose the one you consider correct and record your choice in soft pencil on the separate Answer Sheet. Read the instructions on the Answer Sheet very carefully. Each correct answer will score one mark. A mark will not be deducted for a wrong answer. Any rough working should be done in this booklet. The use of an approved scientific calculator is expected, where appropriate. ____________________________________________________________________________ This Question Paper consists of 16 printed pages.

River Valley High School Page 2 of 19 Year 6 H2 Biology 9744 Paper 1 2017 Preliminary Examination II 1 The figure below shows an electron micrograph with two plant cells. Peter v. Sengbusch - b-online@botanik.uni-hamburg.de Which of the following statements correctly describes the labelled structures? 1 R contains circular DNA and is found in both prokaryotic and eukaryotic cells. 2 P has a fluid mosaic structure and regul ates the movement of substances between the two plant cells. 3 S acts as a selective permeable barrier. 4 Q contains enzymes which play an important role in cell specialisation. A 1 and 3 B 3 and 4 C 1, 2 and 3 D All of the above 2 Which of the following statements regarding stem cells are not correct? 1 Stem cells are present within various organs of the adult body. 2 Stem cells can develop into a whole organism when implanted into the womb. 3 Stem cells can be grown indefinitely in culture under appropriate culture conditions. 4 Stems cells isolated from a 3-5 day old human embryo can differentiate into only one kind of cells. P R Q S

River Valley High School Page 3 of 19 Year 6 H2 Biology 9744 Paper 1 2017 Preliminary Examination II 5 Induced pluripotent stem cells have the same developmental potential as embryonic stem cells. A 1 and 3 only B 2 and 4 only C 2, 3 and 5 D 1, 2 and 3 3 Graph A shows the transport of molecule X, with the help of carrier proteins, over time. A student predicted that the alteration of one variable would result in graph B. Which row shows the correct transport process and the alteration in variable that would result in graph B? Transport process Alteration resulting in graph B A facilitated diffusion increase in environmental temperature to 90 °C B active transport increase in concentration of X in cell C facilitated diffusion increase in number of carrier proteins D active transport increase in availability of ATP 4 A student prepared three solutions of sugars, X, Y and Z, and diluted them to varying concentrations. A sample of each was heated with Benedict’s reagent, with or without prior acid hydrolysis. The results are shown below. Concentration of solution/moldm-3 0.0001 0.001 0.01

River Valley High School Page 4 of 19 Year 6 H2 Biology 9744 Paper 1 2017 Preliminary Examination II no acid with acid no acid with acid no acid with acid X Blue solution Blue solution Green mixture Green mixture Orange mixture Orange mixture Y Blue solution Green mixture Blue solution Green mixture Blue mixture Orange mixture Z Blue solution Green mixture Green mixture Green mixture Orange mixture Orange mixture Based on the results, which of the following conclusions is not correct? A Solution Y does not consist of monosaccharides. B Solution X and solution Y consists of disaccharides only. C Solution X consists of monosaccharides only. D Solution Z contains disaccharides. 5 The R groups of two amino acids are shown below. Amino acid R group Serine -CH 2 -OH Alanine -CH 3 When placed in aqueous medium, where in a globular protein will these amino acids be found? A Both serine and alanine will be found in the interior of the globular protein. B Both serine and alanine will be found on the exterior of the globular protein. C Alanine will be found in the interior, and serine on the exterior of the globular protein. D Alanine will be found on the exterior, and serine in the interior of the globular protein. 6 The equations below show the relationship between an enzyme ( E) and its substrate (S), product (P) and an inhibitor (I). Pathway A: E + S  E + P Pathway B: E + S + I  E + S + I In the above reactions, assume that  increasing the concentration of S increases the activity of the enzyme,

River Valley High School Page 5 of 19 Year 6 H2 Biology 9744 Paper 1 2017 Preliminary Examination II  at low substrate concentrations the presence of I reduces rate of reaction velocity, and  the same maximum rate of reaction can be reached in the presence or absence of I. Which mechanism is operating in pathway B? A Positive feedback B Negative feedback C Competitive inhibition D Non-competitive inhibition 7 Bacteria were cultured in a medium containing heavy nitrogen ( 15N) until all their DNA were labelled. These bacteria were then grown in a medium containing only light nitrogen (14N) for five generations. The percentage DNA strands containing 15N in each generation was estimated. Which curve provides evidence that each daughter DNA molecule produced consists of a parental strand and a newly synthesised daughter strand? C 8 Part of the amino acid sequence in β-globin chains of normal and mutant haemoglobin are shown. Normal haemoglobin thr-pro-glu-glu

River Valley High School Page 6 of 19 Year 6 H2 Biology 9744 Paper 1 2017 Preliminary Examination II Mutant haemoglobin thr-pro-val-glu Possible mRNA codons for these amino acids are Glutamine (glu) GAA GAG Threonine (thr) ACU ACC Proline (pro) CCU CCC Valine (val) GUA GUG Which tRNA molecule is not involved in the formation of this part of amino acid sequence in mutant haemoglobin? A B C D 9 Tay-Sachs disease is characterised by abnormal accumulation of lipid-related compounds, which results in deterioration of cognitive and motor abilities. It is caused by an autosomal recessive mutati on in the allele coding for hexosaminidase A (HEXA), an enzyme that regulates the metabolism of phospholipids. The base triplets in part of the coding DNA sequences for a normal HEXA allele and a mutant Tay-Sachs allele, as well as their corresponding amino acids are shown. Normal HEXA allele CGT ATA TCC TAT GCC CCT GAC… Arg Ile Ser Tyr Gly Pro Asp Tay- Sachs allele CGT ATA TCT ATC CTA TGC CCC TGA… Arg Ile Ser Ile Leu Cys Pro Thr Which combination correctly describes the nature of mutation that results in the Tay- Sachs allele?

River Valley High School Page 7 of 19 Year 6 H2 Biology 9744 Paper 1 2017 Preliminary Examination II Changes to nucleotide sequences Alteration of reading frame Length of polypeptide A Deletion of 2 bases Yes Shorter B Insertion of 2 bases Yes Longer C Substitution of 4 bases No Unchanged D Insertion of 4 bases Yes Longer 10 Which row correctly identifies the characteristics of the human genome? Promoter Histone proteins bound to DNA Centromeres Repeated sequences A Multiple Always Position varies for every chromoso