1 What is the general formula for starch?

A (C5H10O5)n B (C5H10O6)n C (C6H10O5)n D (C6H12O6)n

2 Collagen is a fibrous protein found in mammalian tendons. Which feature contributes most to the great tensile strength of collagen?

A a quaternary structure of triple helices bonded together with covalent and hydrogen bondsB a secondary structure with many hydrogen bonds firmly holding α-helicesC a regularly folded tertiary structure held together with hydrogen bonds and ionic bondsD a primary sequence with covalent bonds linking a variable sequence of amino acids

3 Which statement about the fluid mosaic model of membrane structure is correct?

A The less unsaturated the fatty acid tails of the phospholipid, the more fluid the membrane.B The more unsaturated the fatty acid tails of the phospholipid, the more fluid the membrane.C The higher the temperature, the less fluid the membrane.D The lower the temperature, the more fluid the membrane.

4 Which statement describes how allosteric enzymes work?

B

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Biology H2 9747Tutor TuteeRevision Exercise 1: MCQ

5 The enzyme phosphofructokinase is involved in phosphorylation of hexose phosphate sugars during glycolysis. It is involved in control of the rate of glycolysis and thus respiration, by end-product inhibition.

Deduce which of the following is a description of this enzyme.

C

6 Students investigated the rate of photosynthesis by measuring the rate of oxygen evolved from an aquatic plant. The results of the two experiments they set up are shown below.

Which conclusion can be drawn only from this data?

A Temperature does not affect the rate of photosynthesis.B High concentrations of CO2 reduce the rate of photosynthesis.C Temperature and CO2 concentration are both limiting factors.D The greater the light intensity the greater the rate of photosynthesis

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7 Which diagram represents the process of cyclic photophosphorylation?

B

8 Analysis of DNA produced the following ratios of nitrogenous bases.

Which statement explains the difference in the ratios?

A Animal DNA contains more purines than pyrimidines.B Different parts of organisms contain different proportions of purines and

pyrimidines.C DNA contains thymine instead of uracil.D There are variations in the accuracy of analytical techniques.

9 Mitochondria are thought to have evolved from prokaryotic cells that were ingested by an ancestral cell.

Which feature have the prokaryotes lost during their evolution into mitochondria?

A cell wallB circular chromosomeC endoplasmic reticulum

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D ribosomes

10 Which process is the movement of molecules that are too large to diffuse in through a cell surface membrane?

A active transportB endocytosisC facilitated diffusionD osmosis

11 The diagram summarises glycolysis.

Which correctly gives the number of carbon atoms and phosphate groups in the four named molecules?

A

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12 Some antibacterial drugs can affect the synthesis of proteins.

Which is the correct set of immediate effects of these drugs?

B

13 Which statement explains Mendel’s law of segregation?

A Alleles separate so that half the gametes receive one allele and the other half of the gametes receive the other allele. B Homologues randomly align during metaphase. C Alleles are inherited together. D Genes segregate independently so that one gamete receives one gene

independently of the other gamete receiving the other gene.

14 A biochemist isolated and purified molecules needed for DNA replication. When some DNA was added replication occurred, but the DNA molecules formed were defective. Each consisted of a normal DNA strand paired with segments of DNA a few hundred nucleotides long. Which of the following had been left out of the mixture?

A DNA ligase B Helicase C Nucleotides D DNA polymerase

15 Which is the correct comparison of DNA with RNA?

A DNA and RNA have the same purines and pyrimidines

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B DNA and RNA have the same purines but different pyrimidinesC DNA and RNA have different purines but the same pyrimidinesD DNA and RNA have different purines and different pyrimidines

16 What are homologous chromosomes?

A Two chromosomes with differing sets of genes, in the same sequence, with the same alleles B Two chromosomes with the same set of genes, in a different sequence, with the same alleles C Two chromosomes with a different set of genes, in the same sequence, with different alleles D Two chromosomes with the same set of genes, in the same sequence, sometimes with different alleles

17 How does recombination normally occur for unlinked genes?

A Crossing-over in Prophase IB Random chromosome assortmentC Failure of spindles to formD Random gene mutations

18 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

19 In three different genetic dictionaries, the genetic code for the amino acid cysteine is given as:

ACA or ACG ORTGT or TGC ORUGU or UGC

The explanation for this may be:

1 Some genetic dictionaries show mRNA codons, others show DNA triplets.2 Some genetic dictionaries show the triplet code complementary to the mRNA code, others show the triplet code for the other strand.3 The genetic code can be read in either the 3’ or 5’ direction along the DNA.4 The genetic code is a degenerate triplet code.

A 3 only B 2 and 4 only C 1, 2 and 3 only D 1, 2 and 4 only

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20 Genes P, Q, R and S are located on the same chromosome. The cross over values between them are:

P–Q 20 %P–R 30 %P–S 15 %Q–R 15 %Q–S 30 %R–S 40 %

What is the sequence of genes in the gene map of the chromosome?

A S, P, Q, RB R, P, Q, SC P, R, S, QD Q, S, R, P

(Discrepancy in the percentages probably so since crossing over is a chance event, so slight difference in about 5% can still be accounted for)

S P Q R

P–Q 15-20 %P–R (15+15=) 30 %

P–S 15 %Q–R 15 %

Q–S (15+15=) 30 %R–S (15+15+15=) 45 % (but still close to 40 %)

21 The initiation of gene expression in prokaryotes involves which of the following mechanisms?

1 -10 promoters2 -35 promoters3 mRNA splicing to remove introns4 promoters many kb upstream

A 4 only B 1 and 2 only C 1, 2 and 3 only D 1, 2, 3 and 4

22 Which is a correct description of the role of calcium ions in the neuromuscular system?

A exchanged with sodium ions through co-transport channels at axon surfaces during the reestablishment of a resting potential after an action potentialB moved in by diffusion through gated ion channels in pre-synaptic membranes of excitatory neurones causing vesicles to move to pre-synaptic membrane as an impulse arrivesC exchanged with chloride ions at the post-synaptic membrane, in changing membrane potential in inhibitory neuronesD actively pumped out of axons at nodes of Ranvier of myelinated neurones, being the main cause of the potential difference that is maintained during the resting potential

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23 After depolorization what happens to restore the resting potential?

A Sodium channels open and sodium ions diffuse out of the neuron B Potassium channels open and potassium ions diffuse into the neuron C Potassium channels open and potassium ions diffuse out of the neuron D Sodium channels open and sodium ions diffuse into the neuron

24 In a genetic engineering experiment a piece of double-stranded DNA containing 6000 nucleotides is transcribed and translated.

What is the total number of amino acids used?

A 500 B 1000 C 2000 D 3000

25 What ensures that mitosis produces two genetically identical nuclei?

A One of each of the twenty-three types of chromosome is pulled to each pole of the cell by spindle microtubules. B Half of the chromosomes are pulled to each centriole by mesosomes. C Identical chromatids are pulled to opposite poles by spindle microtubules. D DNA molecules are moved to the equator of the cell where they are replicated.

26 Which of the following describe processes that lead to an increase in variation?

1 breaking and rejoining in homologous chromosomes during prophase 1 of meiosis2 random distribution of homologous chromosomes to the cell poles during anaphase 1 of meiosis3 random variation in allele frequency with time that may result in alleles becoming more common4 the production of new alleles by substitution of one base for another in DNA

A 1 and 4 only B 2 and 3 only C 1, 2 and 4 only D 1, 3 and 4 only

27 The scientific names of two organisms are shown below.

Lathyrus palustris Angelica palustris

What is the relationship between these organisms?

A They both belong to the same genus but they are different speciesB They both belong to the same species but different generaC They are both different species and different generaD They both belong to the same species and the same genus

28 The diagrams show two gull species found in western Europe, the herring gull and the lesser black backed gull.

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These were described as an example of a ‘ring species’ by Mayr in 1942. It is now thought that they are not ‘ring species’.

Which of the following pieces of evidence shows that these gull species may not have originated as ‘ring species’?

1 Genetic profiling suggests that the European and North American herring gulls share a common ancestor but neither is descended from the other.2 Mitochondrial DNA suggests that the ancestors of several of the ‘intermediates’ are from regions outside the ‘ring’.3 Morphological similarities are much greater than genetic similarities, thought to be due to convergent evolution between gulls of different lineages.4 There is disagreement among ornithologists whether there are two species with many sub-species or whether there are up to 20 different species of such gulls

A 3 only B 4 only C 1 and 2 only D 1, 2 and 3 only

29 How many molecules of acetyl CoA (ethanoyl CoA) does the oxidation of the fatty acid stearic acid produce?

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A 2B 6C 9D 18

30 During the development of the AIDS virus, a long polypeptide is hydrolysed by a protease enzyme, producing several smaller peptides. This viral enzyme is the target of new anti-AIDS drugs.

Which feature is essential for the success of these drugs?

A a complex structure that inhibits many types of viral enzymeB a molecule containing a heavy metal atom that is a non-competitive inhibitor of enzymesC a protein that can act as a competitive inhibitor of protease enzymesD a specific structure that inhibits only viral protease

31 In isolating the gene that produces human insulin, reverse transcriptase was used.

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Which is the reason that reverse transcriptase is not used for isolating the gene that produces a human sodium ion/calcium ion channel protein?

A The amino acid sequence for this protein is not known so this is a gene that has not yet been located by the human genome project.B Reverse transcriptase is a viral enzyme, and in the current environment of suspicion of viruses, it is not possible to use such enzymes.C The antibiotic resistance genes transferred by reverse transcriptase with the insulin gene may be transferred to pathogens.D The ion channel protein gene is expressed at low levels in human cells so the mRNA produced is swamped by other mRNA.

32 The photograph shows Dolly the sheep (and her lamb, Bonnie). Dolly was cloned and born at the Roslin Institute in 1996. Sheep of this type normally live to 12 years of age but Dolly died aged 6.

Which of the following have been suggested as having contributed to Dolly’s early demise?

1 cartilage cells in her joints aged prematurely due to insufficient telomere length2 the cell from which she was cloned did not have its telomere length re-set by meiosis3 the in-vitro procedures used caused telomere length re-setting4 the premature ageing of cartilage in her joints resulted from excessive telomere length

A 1 and 2 only B 1 and 3 only C 2 and 3 only D 2 and 4 only

33 In which ways is the polymerase chain reaction (PCR) similar to the replication of DNA?

1 DNA is heated to break hydrogen bonds2 DNA unzips3 free nucleotides are used4 DNA polymerase enzymes are required

A 1 only B 2 and 4 only C 1, 2 and 3 only D 2, 3 and 4 only

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34 Replica plating is a method used to detect which bacteria have been successfully transformed during genetic engineering.

Which explains why other methods for detecting successful transformation are now preferred?

1 Incorporating heavy-metal resistance genes along with the desired genes means that you can easily kill cells that have not been transformed.2 Presence or absence of non-toxic fluorescent markers is easy to detect using ultra- violet light.3 The antibiotic resistance genes previously used as markers might have escaped into the environment.4 The antibiotic resistance genes previously used as markers killed the transformed cells so they were difficult to use.

A 1 and 3 only B 2 and 4 only C 1, 2 and 3 only D 1, 2, 3 and 4

35 A patient suffers from adenosine deaminase deficiency (ADA), an autosomal reccessive immune deficiency, in which bone marrow lymphoblasts cannot replicate to generate immunocompetent lymphocytes. The treatment option that would permanently cure the patient is

A germ-line gene therapy to replace one ADA gene copyB germ-line gene therapy to replace both ADA gene copies. C somatic cell gene therapy to replace both ADA gene copies in circulating

lymphocytes. D somatic cell gene therapy to replace one ADA gene copy in bone marrow

lymphoblasts.

36 Five VNTR markers have been mapped to chromosome 19. A gene for an autosomal dominant disease with 100% penetrance has also been mapped to chromosome 19. This data has been obtained from a family with affected individuals.

Which VNTR marker is most likely to be linked to the disease gene locus based on this family’s data?

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A VNTR-1B VNTR-2C VNTR-3D VNTR-4E VNTR-5

37 Which of following is the most likely explanation for the occurrence of the following individual?

A Non-disjunction in meiosis I of the fatherB Non-disjunction in meiosis II of the fatherC Non-disjunction in meiosis I of the mother

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D Non-disjunction in meiosis II of the mother

38 The key portion of the autoradiograph from a single locus probe analysis of various DNA samples in a rape investigation is shown in this figure.

Samples of DNA were loaded into the following lanes:

1. known blood sample of victim2. known blood sample from defendant3. DNA size markers4. female fraction from vaginal swab of victim5. male fraction from vaginal swab of victim.

If you are the DNA analyst, you should conclude that:

A The suspect is guiltyB The suspect might be guilty, but more probes should be usedC The vaginal swab is from the wrong victimD The suspect is excluded as a source of DNA in the evidence

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39 Results from a single locus probe DNA fingerprint analysis for a man and woman and their four children are shown in the autoradiograph to the right. Which child is least likely to be the biological offspring of this couple?

A Child 1B Child 2C Child 3D Child 4

40 A palaeontologist recovered a bit of tissue from the preserved skin of an extinct dodo. The researcher would like to compare DNA from the sample to that of living birds. Which of the following would be the most useful in increasing the amount of dodo DNA available for testing? 

A RFLP (restriction fragment length polymorphism) analysis B PCRC electroporationD Gel electrophoresis 

End of Paper

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