Structure of nucleic acids and replication of DNA — Paper 1 · A Level Biology 9700

1 The diagram shows the ultrastructure of a eukaryotic cell. Which organelle does not contain nucleic acid? A D C B

1 marks

Answer: A

This question in 9700/11 Oct/Nov 2004

20 Human cells contain 46 chromosomes. The diagram shows a human cell in prophase of mitosis (cell 1) and the daughter cells just after telophase (cells 2 and 3). cell 1 cell 2 cell 3 How many DNA molecules are there in the nucleus of cell 1 and cell 2? cell 1 cell 2 A 46 23 B 46 46 C 92 23 D 92 46

1 marks

Answer: D

This question in 9700/11 Oct/Nov 2004

25 Analysis of DNA produced the following ratios of nitrogenous bases. ratio of purines source of DNA to pyrimidines bean seeds 0.99 cow heart 1.01 human liver 1.02 rat bone marrow 1.00 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.

1 marks

Answer: D

This question in 9700/11 Oct/Nov 2004

18 Which cell activity must occur before prophase of mitosis can begin? A breakdown of the nuclear envelope B increased production of mRNA C migration of centrioles to opposite poles D replication of DNA

1 marks

Answer: D

This question in 9700/11 May/June 2006

20 The diagram shows the mitotic cell cycle. When radioactive nucleotides are supplied to dividing cells, at which point will they be incorporated into the chromosomes? mitosis B C D A interphase

1 marks

Answer: A

This question in 9700/11 May/June 2006

21 The diagram shows part of a DNA molecule. Which part is a nucleotide? C B A D

1 marks

Answer: A

This question in 9700/11 May/June 2006

22 Bacteria were grown for many generations in a medium containing a heavy isotope of nitrogen, 15N. They were then transferred to a medium containing the light isotope of nitrogen, 14N. They were given time to replicate DNA and divide once. Their DNA was extracted, spun in a centrifuge and observed using ultra violet light. The DNA with the 15N settled at a lower depth than the DNA with the 14N. Which shows the predicted results after one generation in the medium with the light isotope? A B C D DNA DNA with 14N with 14N DNA with 14N and 15N DNA DNA with 15N with 15N

1 marks

Answer: C

This question in 9700/11 May/June 2006

24 DNA from a chromosome is analysed and 20 % of its bases are found to be cytosine. Which percentage of uracil molecules will be found in mRNA transcribed from this DNA? A 20 B 30 C 40 D 60

1 marks

Answer: B

This question in 9700/11 May/June 2006

19 A diploid nucleus in a species of fruit fly has 8 chromosomes. How many DNA molecules are present in the nucleus at the end of interphase? A 4 B 8 C 16 D 32

1 marks

Answer: C

This question in 9700/11 Oct/Nov 2006

20 What is the function of the enzyme DNA polymerase in a cell? A to synthesise a polypeptide using DNA as a template B to synthesise a strand of DNA using a polypeptide as a template C to synthesise a strand of DNA using DNA as a template D to synthesise a strand of mRNA using DNA as a template

1 marks

Answer: C

This question in 9700/11 Oct/Nov 2006

21 A culture of bacteria had all its DNA labelled with the heavy isotope of nitrogen, 15N. The culture was then allowed to reproduce using nucleotides containing normal 14N. The DNA was examined using a centrifuge after one generation and again after two generations. The diagram shows the position of the DNA band at Z in the centrifuge tube when the DNA was first labelled. X Y Z In which pattern would the DNA be found after the first and after the second cell generations? after first generation after second generation A half at X and half at Y quarter at X, quarter at Z and half at Y B half at X and half at Z quarter at X, quarter at Z and half at Y C all at Y half at X and half at Y D all at Z half at Y and half at Z

1 marks

Answer: C

This question in 9700/11 Oct/Nov 2006

23 Mammalian skin cells in tissue culture were supplied with a source of radioactive thymine. At which stage in the cell cycle will the thymine be used in the nuclei? A interphase B metaphase C prophase D telophase

1 marks

Answer: A

This question in 9700/11 Oct/Nov 2006

20 The diagram shows part of a DNA molecule. Where are hydrogen bonds found? A B C D

1 marks

Answer: D

This question in 9700/11 Oct/Nov 2007

22 The diagram shows a process involving DNA. What is the name of the process and the stage in the cell cycle at which it occurs? process stage A replication interphase B replication prophase C transcription interphase D transcription prophase

1 marks

Answer: A

This question in 9700/11 May/June 2008

23 The diagram shows two bases, X and Y, joined by hydrogen bonds (----) in DNA. H O N H O N H C C C C C H N H C N N C Y N C C N X O H N H What are the correct bases? X Y A adenine cytosine B adenine uracil C cytosine guanine D cytosine thymine

1 marks

Answer: C

This question in 9700/11 May/June 2008

2 From which cell organelle are nucleic acids absent? A chloroplast B Golgi apparatus C mitochondrion D ribosome

1 marks

Answer: B

This question in 9700/11 Oct/Nov 2008

7 Which substances contain carbon, hydrogen, oxygen and nitrogen? 1 amylopectin 2 collagen 3 deoxyribonucleic acid A 2 only B 1 and 2 only C 2 and 3 only D 1, 2 and 3

1 marks

Answer: C

This question in 9700/11 Oct/Nov 2008

20 Which diagram shows the bond linking the individual units of a nucleic acid? A B C D H C O C C C O C C N C C C O P O C O O

1 marks

Answer: C

This question in 9700/11 Oct/Nov 2008

21 What does the enzyme DNA polymerase synthesise in a cell? A a polypeptide using DNA as a template B a strand of DNA using a polypeptide as a template C a strand of DNA using DNA as a template D a strand of mRNA using DNA as a template

1 marks

Answer: C

This question in 9700/12 Oct/Nov 2009

22 The following statements describe events that take place during DNA replication and transcription. Which statement is not correct? DNA transcription replication A adenine pairs with thymine yes no B both DNA polynucleotide chains act as templates yes no C the original DNA molecule is changed after the process no yes D uracil pairs with adenine no yes

1 marks

Answer: C

This question in 9700/12 Oct/Nov 2009

24 Which diagram shows the semi-conservative replication of a section of a molecule of DNA? A B T T A T U A G G C G G C G P G C G P G C P P C C G C C G P P A P T A P T A A P P G P C G P C G G T A T A T A T A C G C G T U A P P T A P P T C G G C G G P P P P C G G C G G P P P P T A A T A A G C C G C C A T T A U T C D U A T A G C G C G C G C C G C G A U A T G C G C U A T A U A T A C G C G T U A P P A U A P P A T P P P P C G C G C G C G P P P P P P P P C G C G C G C G P P P P P P P P U A T A T A U A G C G C G C G C A T A U A U A T

1 marks

Answer: A

This question in 9700/12 Oct/Nov 2009

21 What would be the result of analysing part of a DNA molecule? A hexose sugars and phosphates in equal proportion, and an equal number of cytosine and guanine bases B nucleotides and phosphates in equal proportion, and an equal number of adenine and cytosine bases C pentose sugars and phosphates in equal proportion, and an equal number of adenine and thymine bases D twice as many phosphates as pentose sugars, and an equal number of adenine and guanine bases

1 marks

Answer: C

This question in 9700/11 May/June 2010

22 DNA is said to replicate in a semi-conservative way. Results of Meselson and Stahl’s experiments gave overwhelming support to this theory. They used E. coli which has a generation time of 50 minutes. Here are the steps in their experiment but they are in the wrong order. P All bacteria contain 15N DNA. Q All bacteria contain hybrid DNA (15N DNA and 14N DNA). R Bacteria contain either all 14N DNA or hybrid DNA. S Bacteria grown in a 15N medium for many generations. T Bacteria transferred to a 14N medium and sampled every 50 minutes. Which sequence of letters shows the correct order of the steps in the experiment? A P → Q → R → S → T B P → S → T → R → Q C S → P → T → Q → R D S → R → Q → P → T

1 marks

Answer: C

This question in 9700/11 May/June 2010

20 DNA is said to replicate in a semi-conservative way. Results of Meselson and Stahl’s experiments gave overwhelming support to this theory. They used E. coli which has a generation time of 50 minutes. Here are the steps in their experiment but they are in the wrong order. P All bacteria contain 15N DNA. Q All bacteria contain hybrid DNA (15N DNA and 14N DNA). R Bacteria contain either all 14N DNA or hybrid DNA. S Bacteria grown in a 15N medium for many generations. T Bacteria transferred to a 14N medium and sampled every 50 minutes. Which sequence of letters shows the correct order of the steps in the experiment? A P → Q → R → S → T B P → S → T → R → Q C S → P → T → Q → R D S → R → Q → P → T

1 marks

Answer: C

This question in 9700/12 May/June 2010

32 What would be the result of analysing part of a DNA molecule? A hexose sugars and phosphates in equal proportion, and an equal number of cytosine and guanine bases B nucleotides and phosphates in equal proportion, and an equal number of adenine and cytosine bases C pentose sugars and phosphates in equal proportion, and an equal number of adenine and thymine bases D twice as many phosphates as pentose sugars, and an equal number of adenine and guanine bases

1 marks

Answer: C

This question in 9700/12 May/June 2010

5 What would be the result of analysing part of a DNA molecule? A hexose sugars and phosphates in equal proportion, and an equal number of cytosine and guanine bases B nucleotides and phosphates in equal proportion, and an equal number of adenine and cytosine bases C pentose sugars and phosphates in equal proportion, and an equal number of adenine and thymine bases D twice as many phosphates as pentose sugars, and an equal number of adenine and guanine bases

1 marks

Answer: C

This question in 9700/13 May/June 2010

25 DNA is said to replicate in a semi-conservative way. Results of Meselson and Stahl’s experiments gave overwhelming support to this theory. They used E. coli which has a generation time of 50 minutes. Here are the steps in their experiment but they are in the wrong order. P All bacteria contain 15N DNA. Q All bacteria contain hybrid DNA (15N DNA and 14N DNA). R Bacteria contain either all 14N DNA or hybrid DNA. S Bacteria grown in a 15N medium for many generations. T Bacteria transferred to a 14N medium and sampled every 50 minutes. Which sequence of letters shows the correct order of the steps in the experiment? A P → Q → R → S → T B P → S → T → R → Q C S → P → T → Q → R D S → R → Q → P → T

1 marks

Answer: C

This question in 9700/13 May/June 2010

20 DNA was extracted from the salivary glands of a fruit fly and a human cheek cell. In which way did the DNA molecules differ? A in the ratio of adenine to thymine B in the sequence of the nucleotides C in the type of pentose sugar D in the types of nucleotide

1 marks

Answer: B

This question in 9700/11 Oct/Nov 2010

21 Which statement describes the semi-conservative replication of DNA? A Parental DNA is broken down into nucleotides and reassembled with new nucleotides. B Parental DNA is split into triplets and new triplets are added. C Parental DNA is split into two strands, each of which is replicated. D Parental DNA remains intact and a new daughter DNA copy is built from new nucleotides.

1 marks

Answer: C

This question in 9700/11 Oct/Nov 2010

22 The table shows the percentages of nitrogenous bases in four samples of nucleic acids. Which base is adenine? percentage of nitrogenous bases sample A B C D uracil 1 19 31 30 19 nil 2 27 23 24 26 nil 3 25 25 nil 25 25 4 17 32 33 18 nil

1 marks

Answer: B

This question in 9700/11 Oct/Nov 2010

23 The table shows the role of four different proteins involved in DNA replication. single-strand protein helicase topoisomerase DNA polymerase binding protein unwinds the breaks and rejoins binds to separated synthesises strand role parental DNA the DNA strands DNA strands to of DNA double helix stabilise them Which shows the function of these proteins? single-strand helicase topoisomerase DNA polymerase binding protein A adds DNA prevents original enables tension makes strands nucleotides to the 3’ strands reforming caused by available as end of a growing complementary unwinding to be templates polynucleotide base pairs released strand B enables tension prevents original makes strands adds DNA caused by strands reforming available as nucleotides to the 3’ unwinding to be complementary templates end of a growing released base pairs polynucleotide strand C enables tension makes strands adds DNA prevents original caused by available as nucleotides to the 3’ strands reforming unwinding to be templates end of a growing complementary released polynucleotide base pairs strand D makes strands enables tension prevents original adds DNA available as caused by strands reforming nucleotides to the 3’ templates unwinding to be complementary end of a growing released base pairs polynucleotide strand

1 marks

Answer: D

This question in 9700/11 Oct/Nov 2010

19 The table shows the percentages of bases in DNA from various types of cell. percentage of bases in DNA source of DNA adenine guanine thymine cytosine calf thymus 28.2 21.5 27.8 22.5 bull spleen 27.9 22.7 27.3 22.1 bull sperm 28.6 22.2 27.2 22.0 rat bone marrow 28.7 21.4 28.4 21.5 yeast 31.3 18.7 32.9 17.1 What is a valid deduction from these data? A All cells from the same species have approximately the same content of DNA. B Small differences in DNA from different cells have large effects. C The four bases show complementary base pairing. D The structure of DNA is different in yeast and animal cells.

1 marks

Answer: C

This question in 9700/12 Oct/Nov 2010

21 A culture of bacteria had all its DNA labelled with the heavy isotope of nitrogen (15N). A sample was taken and spun in a centrifuge. The diagram shows the position of the DNA band at Z in the centrifuge tube. X Y Z The culture was then allowed to reproduce using nucleotides containing the normal isotope of nitrogen (14N). Samples were taken and spun in a centrifuge after one generation and again after two generations. In which pattern would the DNA be found after the first and after the second generations? after first generation after second generation A half at X and half at Y quarter at X, quarter at Z and half at Y B half at X and half at Z quarter at X, quarter at Z and half at Y C all at Y half at X and half at Y D all at Z half at Y and half at Z

1 marks

Answer: C

This question in 9700/12 Oct/Nov 2010

21 The mechanism of action of four drugs that inhibit DNA replication is stated below. ● Aphidicholine inhibits DNA polymerase. ● Cytarabine is converted into a molecule that can substitute for a DNA nucleotide and also inhibits DNA repair mechanisms. ● Epirubicin inhibits an enzyme involved in the unwinding of DNA and separation of strands. ● Hydroxycarbamide inhibits an enzyme involved in the production of deoxyribonucleotides. Which row correctly matches a drug to an explanation of the mechanism of action? explanation of mechanism of action decreased pool of DNA strands not DNA damaged exposed DNA available available as during replication template strands nucleotides inhibits templates for and cell death unable to be copied chain elongation transcription occurs A aphidicholine epirubicin cytarabine hydroxycarbamide B epirubicin cytarabine hydroxycarbamide aphidicholine C hydroxycarbamide aphidicholine epirubicin cytarabine D hydroxycarbamide epirubicin cytarabine aphidicholine

1 marks

Answer: D

This question in 9700/11 May/June 2011

23 Which type of sugar and types of bonds are found in a DNA molecule? type of sugar types of bonds A non-reducing hydrogen and ionic B non-reducing hydrogen and peptide C reducing covalent and hydrogen D reducing hydrogen and peptide

1 marks

Answer: C

This question in 9700/11 May/June 2011

21 The table shows the tRNA anticodons for four amino acids. amino acid anticodon (tRNA) asparagine UUA glutamic acid CUU proline GGA threonine UGG A cell makes a polypeptide with the following amino acid sequence. glutamic acid – asparagine – threonine – proline What was the sequence of bases on the DNA from which this was formed? A GGAAATACCCTT B CAAAATACCCCT C CTTTTATGGGGA D CTTTTATCCGGA

1 marks

Answer: C

This question in 9700/12 May/June 2011

23 The diagram shows part of a DNA molecule. A T G C C G C G How many hydrogen bonds are involved in holding these strands of DNA together? A 11 B 9 C 8 D 4

1 marks

Answer: A

This question in 9700/12 May/June 2011

25 Which type of sugar and types of bonds are found in a DNA molecule? type of sugar types of bonds A non-reducing hydrogen and ionic B non-reducing hydrogen and peptide C reducing covalent and hydrogen D reducing hydrogen and peptide

1 marks

Answer: C

This question in 9700/13 May/June 2011

30 The mechanism of action of four drugs that inhibit DNA replication is stated below. ● Aphidicholine inhibits DNA polymerase. ● Cytarabine is converted into a molecule that can substitute for a DNA nucleotide and also inhibits DNA repair mechanisms. ● Epirubicin inhibits an enzyme involved in the unwinding of DNA and separation of strands. ● Hydroxycarbamide inhibits an enzyme involved in the production of deoxyribonucleotides. Which row correctly matches a drug to an explanation of the mechanism of action? explanation of mechanism of action decreased pool of DNA strands not DNA damaged exposed DNA available available as during replication template strands nucleotides inhibits templates for and cell death unable to be copied chain elongation transcription occurs A aphidicholine epirubicin cytarabine hydroxycarbamide B epirubicin cytarabine hydroxycarbamide aphidicholine C hydroxycarbamide aphidicholine epirubicin cytarabine D hydroxycarbamide epirubicin cytarabine aphidicholine

1 marks

Answer: D

This question in 9700/13 May/June 2011

21 What makes the exact copying of DNA molecules possible? A base pairing B hydrogen bonding between nucleotides C sugar-phosphate backbone D the double helix shape

1 marks

Answer: A

This question in 9700/11 Oct/Nov 2011

23 Bacteria were grown in a medium containing 15N. After several generations, all of the DNA contained 15N. Some of these bacteria were transferred to a medium containing the common isotope of nitrogen, 14N. The bacteria were allowed to divide once. The DNA of some of these bacteria was extracted and analysed. This DNA was all hybrid DNA containing equal amounts of 14N and 15N. The remaining bacteria were left in the medium with 14N and allowed to divide one more time. The DNA of some of these bacteria was extracted and analysed. What is the composition of this DNA? A 25 % hybrid DNA B 50 % hybrid DNA C 75 % hybrid DNA D 100 % hybrid DNA

1 marks

Answer: B

This question in 9700/11 Oct/Nov 2011

29 What makes the exact copying of DNA molecules possible? A base pairing B hydrogen bonding between nucleotides C sugar-phosphate backbone D the double helix shape

1 marks

Answer: A

This question in 9700/13 Oct/Nov 2011

31 A gene codes for the production of a protein, p53, that binds to damaged DNA during interphase and prevents its replication. A carcinogen in cigarette smoke mutates this gene. Which statement explains why this mutation may cause cancer? A Lack of p53 allows cells to undergo mitosis. B Lack of p53 allows cells with damaged DNA to replicate. C The carcinogen in cigarette smoke increases the rate of cell division. D The p53 causes uncontrolled cell division.

1 marks

Answer: B

This question in 9700/13 Oct/Nov 2011

33 Bacteria were grown in a medium containing 15N. After several generations, all of the DNA contained 15N. Some of these bacteria were transferred to a medium containing the common isotope of nitrogen, 14N. The bacteria were allowed to divide once. The DNA of some of these bacteria was extracted and analysed. This DNA was all hybrid DNA containing equal amounts of 14N and 15N. The remaining bacteria were left in the medium with 14N and allowed to divide one more time. The DNA of some of these bacteria was extracted and analysed. What is the composition of this DNA? A 25 % hybrid DNA B 50 % hybrid DNA C 75 % hybrid DNA D 100 % hybrid DNA

1 marks

Answer: B

This question in 9700/13 Oct/Nov 2011

11 Which substances contain carbon, hydrogen, oxygen and nitrogen? 1 collagen 2 amylopectin 3 deoxyribonucleic acid A 2 only B 1 and 3 only C 2 and 3 only D 1, 2 and 3

1 marks

Answer: B

This question in 9700/11 May/June 2012

21 During semi-conservative replication of DNA in eukaryotic cells, the following processes occur. 1 Free nucleotides are hydrogen bonded to those on the exposed strand. 2 Hydrogen bonds are broken between the complementary base pairs. 3 The cell receives the signal to begin to divide. 4 Covalent bonds form between adjacent nucleotides on the same strand. 5 The DNA double helix is unwound. Which shows the correct order of some of the processes? A 3 → 1 → 2 → 4 B 3 → 2 → 4 → 5 C 5 → 2 → 1 → 4 D 5 → 2 → 3 → 1

1 marks

Answer: C

This question in 9700/11 May/June 2012

15 Which substances contain carbon, hydrogen, oxygen and nitrogen? 1 collagen 2 amylopectin 3 deoxyribonucleic acid A 2 only B 1 and 3 only C 2 and 3 only D 1, 2 and 3

1 marks

Answer: B

This question in 9700/13 May/June 2012

25 During semi-conservative replication of DNA in eukaryotic cells, the following processes occur. 1 Free nucleotides are hydrogen bonded to those on the exposed strand. 2 Hydrogen bonds are broken between the complementary base pairs. 3 The cell receives the signal to begin to divide. 4 Covalent bonds form between adjacent nucleotides on the same strand. 5 The DNA double helix is unwound. Which shows the correct order of some of the processes? A 3 → 1 → 2 → 4 B 3 → 2 → 4 → 5 C 5 → 2 → 1 → 4 D 5 → 2 → 3 → 1

1 marks

Answer: C

This question in 9700/13 May/June 2012

21 Which features of DNA enable it to meet these requirements as a molecule of inheritance? requirement of DNA molecule ability to remain ability to contain ability to transfer ability to replicate stable information information A complementary formation of mRNA sequence of sugar-phosphate base pairing for translation nucleotides backbone B formation of mRNA complementary sugar-phosphate sequence of for translation base pairing backbone nucleotides C sequence of sugar-phosphate complementary formation of mRNA nucleotides backbone base pairing for translation D sugar-phosphate sequence of formation of mRNA complementary backbone nucleotides for translation base pairing

1 marks

Answer: D

This question in 9700/11 Oct/Nov 2012

22 Which diagram shows the bond linking the individual units of a nucleic acid? A B C D H C O C C C O C C N C C C O P O C O O

1 marks

Answer: C

This question in 9700/11 Oct/Nov 2012

21 Which is not a description of a gene? A a length of DNA which carries coded information as a sequence of nucleotides that can result in the formation of a polypeptide chain B any section of a molecule that has two strands, each with a sequence of nucleotides that are complementary to each other and are held together by hydrogen bonding C a sequence of nucleotides which can be copied by complementary base pairing and then be translated at a ribosome D a sequence of nucleotides that can be transcribed using a polymerase enzyme and free activated nucleotides and which results in the formation of a messenger RNA molecule

1 marks

Answer: B

This question in 9700/12 Oct/Nov 2012

22 Which row in the table correctly shows situations in which both DNA and RNA are both involved? replication | transcription | translation v v x key JY involved 0 0O DW > Jv x Jv x Jv x X not involved x x Jv

1 marks

Answer: C

This question in 9700/12 Oct/Nov 2012

22 What is the maximum number of hydrogen bonds in a length of DNA containing 700 base pairs? A 350 B 700 C 1400 D 2100

1 marks

Answer: D

This question in 9700/11 May/June 2013

22 What is the maximum number of hydrogen bonds in a length of DNA containing 700 nucleotides? A 350 B 700 C 1050 D 2100

1 marks

Answer: C

This question in 9700/12 May/June 2013

24 What is the minimum number of hydrogen bonds in a length of DNA containing 700 nucleotides? A 350 B 700 C 1050 D 1400

1 marks

Answer: B

This question in 9700/13 May/June 2013

19 A short piece of DNA 19 base pairs long was analysed to find the number of nucleotide bases in each of the polynucleotide strands. Some of the results are shown below. number of nucleotide bases A C G T strand 1 4 strand 2 7 5 How many nucleotides containing C were present in strand 1? A 2 B 3 C 5 D 7

1 marks

Answer: B

This question in 9700/11 Oct/Nov 2013

20 Which statements about complementary base pairing are correct? 1 Cytosine forms two hydrogen bonds with guanine. 2 Purines and pyrimidines are different sizes. 3 Adenine forms the same number of hydrogen bonds with thymine and uracil. 4 The base pairs are of equal length. A 1, 2 and 3 only B 1, 2 and 4 only C 1, 3 and 4 only D 2, 3 and 4 only

1 marks

Answer: D

This question in 9700/11 Oct/Nov 2013

21 What does the enzyme DNA polymerase synthesise in a cell? A a polypeptide using DNA as a template B a strand of DNA using a polypeptide as a template C a strand of DNA using DNA as a template D a strand of mRNA using DNA as a template

1 marks

Answer: C

This question in 9700/11 Oct/Nov 2013

19 The following statements describe events that take place during DNA replication and transcription. Which row is not correct? DNA transcription replication A adenine pairs with thymine yes no B both DNA polynucleotide chains act as templates yes no C the original DNA molecule is changed after the process no yes D uracil pairs with adenine no yes

1 marks

Answer: C

This question in 9700/12 Oct/Nov 2013

20 Which statements about complementary base pairing are correct? 1 Purines and pyrimidines are different sizes. 2 It occurs during translation. 3 The base pairs are of different length. 4 Uracil forms two hydrogen bonds with adenine. A 1, 2 and 3 only B 1, 2 and 4 only C 1, 3 and 4 only D 2, 3 and 4 only

1 marks

Answer: B

This question in 9700/12 Oct/Nov 2013

19 What is the minimum number of hydrogen bonds in a length of DNA containing 700 base pairs? A 350 B 700 C 1400 D 2100

1 marks

Answer: C

This question in 9700/13 Oct/Nov 2013

21 Which statements about complementary base pairing are correct? 1 It occurs during translation. 2 Purines and pyrimidines are the same size. 3 The base pairs are of equal length. 4 Uracil forms three hydrogen bonds with adenine. A 1 and 2 only B 1 and 3 only C 2 and 3 only D 3 and 4 only

1 marks

Answer: B

This question in 9700/13 Oct/Nov 2013

21 Which diagram represents a correct base pair of DNA? A B P A T P P C G P C D P C G P P A T P

1 marks

Answer: B

This question in 9700/11 May/June 2014

23 Two sets of bacteria were grown using different types of nitrogen-containing growth media. One set was grown in a medium containing the ‘heavy’ isotope of nitrogen, 15N, until all the DNA was labelled. The other set were grown in a medium containing the ‘light’ isotope of nitrogen, 14N, until all the DNA was labelled. The DNA from each set of bacteria was extracted and centrifuged. The diagram shows the position in the centrifuge tubes of this DNA. DNA with 14N DNA with 15N Bacteria with 15N labelled DNA were transferred to a medium containing 14N and allowed to reproduce once. The DNA of the new generation of bacteria was extracted and centrifuged. Which tube shows the position of DNA from this new generation of bacteria? A B C D

1 marks

Answer: D

This question in 9700/11 May/June 2014

20 Which nucleic acid bases are pyrimidines? A adenine and guanine B adenine, cytosine and thymine C cytosine, thymine and uracil D guanine, cytosine and uracil

1 marks

Answer: C

This question in 9700/12 May/June 2014

22 A short piece of DNA fifteen base pairs long was analysed to find the number of nucleotide bases in each of the polynucleotide strands. Some of the results are shown below. number of nucleotide bases A C G T strand 1 6 3 strand 2 4 How many nucleotides containing adenine (A) were present in strand 2? A 2 B 3 C 4 D 6

1 marks

Answer: A

This question in 9700/12 May/June 2014

22 The diagram shows some relationships between different nucleic acid bases. 1 2 3 4 5 Which row is correct? 1 2 3 4 5 A adenine purine cytosine pairs with guanine B cytosine purine guanine pairs with uracil C guanine pairs with cytosine pyrimidine thymine D thymine pairs with uracil pyrimidine adenine

1 marks

Answer: C

This question in 9700/13 May/June 2014

23 The diagram shows the structures of some drugs that have a similar structure to nucleotides. The presence of these drugs reduces nucleic acid synthesis. O O HN N HN N N N N N H2N H2N HO O HO O OH acyclovir gancyclovir Which statement explains how these drugs reduce nucleic acid synthesis? A Increasing the concentration of these drugs results in the increased length of the nucleic acid. B They are non-competitive inhibitors of the enzymes that catalyse the synthesis of DNA or RNA. C They bind to pyrimidine nucleotides and the base pair is the wrong size. D They replace purine nucleotides causing the synthesis of incomplete nucleic acids.

1 marks

Answer: D

This question in 9700/13 May/June 2014

18 The diagram shows part of a DNA molecule. 2 3 1 4 Which regions contain phosphate groups? A 1 and 2 B 1 and 4 C 3 and 4 only D 2, 3 and 4

1 marks

Answer: C

This question in 9700/11 Oct/Nov 2014

21 Which type of sugar and types of bonds are found in a DNA molecule? type of sugar types of bonds A non-reducing hydrogen and ionic B non-reducing hydrogen and peptide C reducing covalent and hydrogen D reducing hydrogen and peptide

1 marks

Answer: C

This question in 9700/12 Oct/Nov 2014

22 Which nucleic acid bases are purines? A adenine and cytosine B cytosine and thymine C guanine and adenine D uracil and cytosine

1 marks

Answer: C

This question in 9700/12 Oct/Nov 2014

23 A short piece of DNA 15 base pairs long was analysed to find the number of nucleotide bases in each of the polynucleotide strands. Some of the results are shown below. number of nucleotide bases A C G T strand 1 6 3 strand 2 4 How many nucleotides containing guanine were present in strand 1? A 2 B 3 C 4 D 6

1 marks

Answer: A

This question in 9700/12 Oct/Nov 2014

19 Which structural feature of the DNA molecule varies? A the arrangement of the sugar-phosphate groups B the double helical arrangement C the number of hydrogen bonds between base pairs D the pairing of the purines with pyrimidines

1 marks

Answer: C

This question in 9700/13 Oct/Nov 2014

20 DNA is said to replicate in a semi-conservative way. Results of Meselson and Stahl’s experiments gave overwhelming support to this theory. They used E. coli which has a generation time of 50 minutes. Here are the stages occuring in their experiment but they are in the wrong order. 14N DNA contains the ‘light’ isotope of nitrogen. 15N DNA contains the ‘heavy’ isotope. P All bacteria contain 15N DNA. Q All bacteria contain hybrid DNA (15N DNA and 14N DNA). R Bacteria contain either all 14N DNA or hybrid DNA. S Bacteria grown in a 15N medium for many generations. T Bacteria transferred to a 14N medium and sampled every 50 minutes. Which sequence of letters shows the correct order of the stages in the experiment? A P → S → T → R → Q B P → T → S → Q → R C S → P → T → Q → R D S → T → P → R → Q

1 marks

Answer: C

This question in 9700/13 Oct/Nov 2014

20 Which row shows two pairs of nucleotides formed during transcription? first base pair transcribed second base pair transcribed number of number of bases bases hydrogen bonds hydrogen bonds A AU 2 CG 2 B AU 2 CG 3 C AU 2 TU 2 D AU 3 CG 2

1 marks

Answer: B

This question in 9700/11 May/June 2015

21 Which row correctly identifies the features of DNA and RNA molecules? DNA and RNA contain both purine DNA and RNA both contain a hydrogen bonds form between bases in and pyrimidine bases | pentose sugar some RNA A v v v B v v x Cc v x v D x v x key / = correct statement X = incorrect statement

1 marks

Answer: A

This question in 9700/11 May/June 2015

22 Two polynucleotide strands make up a DNA molecule. What is a correct description? A The percentage of cytosine is 50% of that of guanine in the whole molecule. B The percentage of cytosine is the same as that of guanine in each strand. C The percentage of cytosine is the same as that of guanine in the whole molecule. D The percentage of cytosine is the same in each strand of the molecule.

1 marks

Answer: C

This question in 9700/11 May/June 2015

22 The diagram shows part of a DNA molecule. A T G C C G C G How many hydrogen bonds are involved in holding these strands of DNA together? A 11 B 9 C 8 D 4

1 marks

Answer: A

This question in 9700/12 May/June 2015

20 Which row correctly describes adenine? component on complementary nucleotide strand ring structure base it is attached to A thymine deoxyribose double B thymine phosphate single C uracil phosphate double D uracil ribose single

1 marks

Answer: A

This question in 9700/13 May/June 2015

22 Which row shows two pairs of nucleotide bases in a molecule of DNA? first base pair second base pair number of number of bases present bases present hydrogen bonds hydrogen bonds A AC 2 GT 3 B AC 3 GT 2 C AT 2 GC 3 D AT 3 GC 2

1 marks

Answer: C

This question in 9700/11 Oct/Nov 2015

20 What occurs during DNA replication and transcription and translation? 1 ATP provides energy. 2 Condensation reactions occur to form a polymer. 3 Hydrogen bonds form between purine and pyrimidine bases. A 1, 2 and 3 B 1 and 2 only C 2 only D 3 only

1 marks

Answer: A

This question in 9700/12 Oct/Nov 2015

22 Which row shows two pairs of nucleotide bases in a molecule of DNA? first base pair second base pair number of number of bases present bases present hydrogen bonds hydrogen bonds A AT 2 CG 2 B AT 2 CG 3 C TA 3 GC 2 D TA 3 GC 3

1 marks

Answer: B

This question in 9700/12 Oct/Nov 2015

22 Which row correctly describes cytosine? number of hydrogen bonds ring structure it forms with its type of base complementary base A double three purine B double two pyrimidine C single three pyrimidine D single two purine

1 marks

Answer: C

This question in 9700/13 Oct/Nov 2015

18 How many of the listed structures typically contain genetic material that has telomeres? • bacterial cell • chloroplast • mitochondrion • nucleus A 1 B 2 C 3 D 4

1 marks

Answer: A

This question in 9700/12 Feb/March 2016

19 What does the enzyme DNA polymerase synthesise in a cell? A a polypeptide using DNA as a template B a strand of DNA using a polypeptide as a template C a strand of DNA using DNA as a template D a strand of mRNA using DNA as a template

1 marks

Answer: C

This question in 9700/12 Feb/March 2016

20 21.2% of the bases in a molecule of DNA are cytosine. What percentage would be adenine? A 21.2% B 28.8% C 42.4% D 57.6%

1 marks

Answer: B

This question in 9700/12 Feb/March 2016

20 DNA contains the ……X…… base ……Y…… which is joined to adenine with ……Z…… hydrogen bonds. Which row correctly completes the statement about DNA? X Y Z A purine thymine three B purine uracil three C pyrimidine thymine two D pyrimidine uracil two

1 marks

Answer: C

This question in 9700/11 May/June 2016

19 Which statements about complementary base pairing are correct? 1 Cytosine forms three hydrogen bonds with guanine. 2 Purines and pyrimidines are different sizes. 3 It allows transcription to occur. 4 The base pairs are of different lengths. A 1, 2 and 3 B 1, 2 and 4 C 1, 3 and 4 D 2, 3 and 4

1 marks

Answer: A

This question in 9700/12 May/June 2016

20 Bacteria were grown in a medium containing 15N. After several generations, all of the DNA contained 15N. Some of these bacteria were transferred to a medium containing the common isotope of nitrogen, 14N. The bacteria were allowed to divide once. The DNA of some of these bacteria was extracted and analysed. This DNA was all hybrid DNA containing equal amounts of 14N and 15N. The remaining bacteria were left in the medium with 14N and allowed to divide one more time. The DNA of some of these bacteria was extracted and analysed. What is the composition of this DNA? A 25% hybrid DNA B 50% hybrid DNA C 75% hybrid DNA D 100% hybrid DNA

1 marks

Answer: B

This question in 9700/12 May/June 2016

19 Which diagram shows a correct ring structure and named nucleic acid base? A B C D adenine cytosine thymine uracil

1 marks

This question in 9700/13 May/June 2016

20 Which statements are correct? 1 Adenine and cytosine are both purines. 2 The DNA nucleotide containing adenine is different from the RNA nucleotide containing adenine. 3 Purines only form base pairs with pyrimidines. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

1 marks

This question in 9700/13 May/June 2016

21 A short piece of DNA 18 base pairs long was analysed to find the number of nucleotide bases in each of the polynucleotide strands. Some of the results are shown below. number of nucleotide bases adenine cytosine guanine thymine strand 1 4 7 strand 2 5 How many nucleotides containing thymine were present in strand 2? A 2 B 4 C 5 D 7

1 marks

This question in 9700/13 May/June 2016

19 The diagram shows part of a DNA molecule. 1 2 4 3 Which labels represent purines? A 1 and 2 B 2 and 4 C 3 and 1 D 4 and 3

1 marks

Answer: B

This question in 9700/11 Oct/Nov 2016

20 A double stranded DNA molecule was analysed and 29% of its nucleotide bases were found to be adenine. What percentage of its nucleotide bases will be cytosine? A 21% B 29% C 42% D 58%

1 marks

Answer: A

This question in 9700/11 Oct/Nov 2016

20 Which diagram shows a correct ring structure and named nucleic acid base? A B C D adenine cytosine thymine uracil

1 marks

Answer: C

This question in 9700/13 Oct/Nov 2016

24 Which statement about nitrogenous bases is correct? A Adenine is a pyrimidine with a double ring structure. B Cytosine is a purine with a double ring structure. C Guanine is a purine with a single ring structure. D Uracil is a pyrimidine with a single ring structure.

1 marks

Answer: D

This question in 9700/12 Feb/March 2017

26 Meselson and Stahl investigated DNA in bacteria. They grew bacteria in a medium with only heavy nitrogen, 15N, until all of the bacterial DNA contained only heavy nitrogen. These bacteria were then moved from the heavy nitrogen medium and cultured in a medium with only light nitrogen, 14N. Some bacteria were collected from each of the next three generations and their DNA was analysed. Hybrid DNA contains both heavy and light nitrogen. Which row shows the correct DNA of the first and third generations? DNA of first generation DNA of third generation A all hybrid half hybrid, half light B all hybrid one quarter hybrid, three quarters light C half hybrid, half heavy half hybrid, one quarter heavy, one quarter light D half hybrid, half light one quarter hybrid, three quarters light

1 marks

Answer: B

This question in 9700/12 Feb/March 2017

24 What is the smallest unit of a DNA molecule that can be altered by a mutation and cause a change to the coding of a polypeptide? A base B codon C gene D nucleotide

1 marks

Answer: D

This question in 9700/11 May/June 2017

26 The table shows the role of four different proteins involved in DNA replication. single-strand protein helicase topoisomerase DNA polymerase binding protein unwinds the breaks and rejoins binds to separated synthesises strand role parental DNA the DNA strands DNA strands to of DNA double helix stabilise them Which shows the function of these proteins? single-strand helicase topoisomerase DNA polymerase binding protein A adds DNA prevents original enables tension makes strands nucleotides to the 3' strands reforming caused by available as end of a growing complementary unwinding to be templates polynucleotide base pairs released strand B enables tension prevents original makes strands adds DNA caused by strands reforming available as nucleotides to the 3' unwinding to be complementary templates end of a growing released base pairs polynucleotide strand C enables tension makes strands adds DNA prevents original caused by available as nucleotides to the 3' strands reforming unwinding to be templates end of a growing complementary released polynucleotide base pairs strand D makes strands enables tension prevents original adds DNA available as caused by strands reforming nucleotides to the 3' templates unwinding to be complementary end of a growing released base pairs polynucleotide strand

1 marks

Answer: D

This question in 9700/11 May/June 2017

27 Which type of sugar and which type of bond are found in a DNA molecule? type of sugar type of bond A non-reducing glycosidic B non-reducing hydrogen C reducing peptide D reducing hydrogen

1 marks

Answer: D

This question in 9700/11 May/June 2017

18 The bacterium Escherichia coli divides once every 50 minutes at 36 °C. E. coli were grown on a medium containing only heavy nitrogen, 15N, until all of the bacterial DNA contained heavy nitrogen (0 minutes). Some of the bacteria were moved from a heavy nitrogen medium and cultured in a medium with only light nitrogen, 14N. Some bacteria were collected after each of three generations. Their DNA was extracted and centrifuged. Hybrid DNA contains heavy and light nitrogen. The diagram shows the possible positions (upper, middle and lower) of the bands of DNA. The actual positions of bands in the first two samples are shown. upper upper middle middle lower lower 0 50 100 150 sample time: minutes minutes minutes minutes Which proportion of the DNA of the sample taken at 150 minutes will be at the upper position? A 25% B 50% C 75% D 100%

1 marks

Answer: C

This question in 9700/12 May/June 2017

21 Which row is correct for adenine? has a single joins to its rin structure is a purine complementary base 9 with 3 hydrogen bonds B WA x x Cc x WA x key JY = correct X = incorrect

1 marks

Answer: C

This question in 9700/12 May/June 2017

18 Which statement about nucleotides is correct? A Adenine and guanine are pyrimidines. B ATP is a phosphorylated nucleotide. C Purines have a single ring structure. D Uracil replaces cytosine in RNA.

1 marks

Answer: B

This question in 9700/13 May/June 2017

19 Scientists have made a nucleic acid (HNA) that has a sugar with the same number of carbon atoms as glucose instead of deoxyribose. Although genetic information can be stored by HNA, naturally occurring DNA polymerase cannot replicate HNA. Which statements could explain why naturally occurring DNA polymerase cannot replicate HNA? 1 DNA polymerase cannot form bonds between the sugars of two HNA nucleotides. 2 DNA polymerase cannot form hydrogen bonds between two HNA nucleotides. 3 HNA nucleotides do not fit into the active site of DNA polymerase. 4 The shape of an HNA nucleotide is slightly larger than that of a DNA nucleotide. A 1, 2, 3 and 4 B 1 and 4 only C 2 and 3 only D 3 and 4 only

1 marks

Answer: D

This question in 9700/13 May/June 2017

20 Meselson and Stahl investigated DNA replication by growing bacteria in a culture containing heavy nitrogen, 15N, until all the DNA was labelled. These bacteria, the parental generation, were then transferred to a culture containing only light nitrogen, 14N, and allowed to replicate for two generations. DNA was extracted from each generation of bacteria and its relative mass estimated. The flow diagram shows the results. sequence of events relative mass of DNA 100% parental generation labelled 15N heavy 100% first generation growth in 14N medium 50% medium second generation growth in 14N 50% light Which row explains the relative mass of the DNA in the second generation grown in 14N? 50% medium DNA molecules 50% light DNA molecules strand 1 strand 2 strand 1 strand 2 A only 15N only 14N only 14N only 14N B only 15N only 15N only 14N only 14N C only 15N only 15N only 14N only 15N D only 15N half 14N, half 15N only 14N half 14N, half 15N

1 marks

Answer: A

This question in 9700/13 May/June 2017

22 What is the maximum number of hydrogen bonds in a length of DNA containing 700 nucleotides? A 350 B 700 C 1050 D 2100

1 marks

Answer: C

This question in 9700/12 Oct/Nov 2017

23 Which statements concerning DNA and RNA are correct? 1 Adenine and guanine are bases that have a double ring structure; cytosine, thymine and uracil are bases with a single ring structure. 2 An adenine nucleotide from DNA is the same as an adenine nucleotide from RNA; DNA adenine pairs with thymine and RNA adenine pairs with uracil. 3 The base pairing that occurs in a double DNA helix and when RNA is synthesised during transcription is always according to the rule that a purine pairs with a pyrimidine. 4 The two polynucleotides on a DNA molecule run in opposite directions so that the double helix formed has two strands that are parallel to each other. A 1, 2 and 3 B 1, 2 and 4 C 1, 3 and 4 D 2, 3 and 4

1 marks

Answer: C

This question in 9700/12 Oct/Nov 2017

24 Two sets of bacteria were grown using different types of nitrogen-containing growth media. One set was grown in a medium containing the ‘heavy’ isotope of nitrogen, 15N, until all the DNA was labelled. The other set was grown in a medium containing the ‘light’ isotope of nitrogen, 14N, until all the DNA was labelled. The DNA from each set of bacteria was extracted and centrifuged. The diagram shows the position in the centrifuge tubes of this DNA. DNA with 14N DNA with 15N Bacteria with 15N labelled DNA were transferred to a medium containing 14N and allowed to reproduce once. The DNA of the new generation of bacteria was extracted and centrifuged. Which tube shows the position of DNA from this new generation of bacteria? A B C D

1 marks

Answer: D

This question in 9700/12 Oct/Nov 2017

23 Rifampicin is an antibiotic used to treat tuberculosis. It works by inhibiting RNA polymerase in bacteria. Which of these processes are prevented by this antibiotic? 1 DNA replication 2 transcription 3 translation A 1, 2 and 3 B 1 and 2 only C 2 and 3 only D 3 only

1 marks

Answer: C

This question in 9700/13 Oct/Nov 2017

25 A single substitution in an allele of the gene coding for haemoglobin results in sickle cell haemoglobin. The mRNA sequence for three amino acids for normal haemoglobin is shown. CCUGAAGAG The mRNA sequence for sickle cell haemoglobin is shown. CCUGUAGAG The table shows some of the triplet codes for two amino acids. DNA triplet codes amino acid CTC Glu CTT Glu CAT Val CAC Val Which row is correct for the substituted DNA nucleotide of the allele and the substituted amino acid of the protein? DNA new amino nucleotide acid A A Glu B A Val C T Glu D T Val

1 marks

Answer: B

This question in 9700/13 Oct/Nov 2017

26 What is the minimum number of hydrogen bonds in a length of DNA containing 700 base pairs? A 350 B 700 C 1400 D 2100

1 marks

Answer: C

This question in 9700/13 Oct/Nov 2017

23 A culture of bacteria was allowed to reproduce using nucleotides containing the heavy isotope of nitrogen (15N). After several generations, all of the bacterial DNA molecules contained heavy nitrogen. DNA was extracted from a sample of the culture, mixed with caesium chloride solution and spun at high speed in a centrifuge. In this process, DNA molecules of different masses separate into bands at different positions in the centrifuge tube. The heavier the DNA molecules, the closer to the bottom of the centrifuge tube that a band forms. The diagram shows the position of the DNA molecules containing heavy nitrogen in the centrifuge tube. K L M The culture of bacteria was then allowed to reproduce using nucleotides containing the light isotope of nitrogen (14N). DNA samples were taken and separated by centrifugation after the bacteria had divided once and again after the bacteria had divided twice. In which positions would the DNA be found after the cells had divided once and after the cells had divided twice? after dividing once after dividing twice A half at K and half at L quarter at K, quarter at M and half at L B half at K and half at M quarter at K, quarter at M and half at L C all at L half at K and half at L D all at M half at L and half at M

1 marks

Answer: C

This question in 9700/12 Feb/March 2018

20 During which phase of the cell cycle does DNA replication take place? A G1 B G2 C M D S

1 marks

Answer: D

This question in 9700/11 May/June 2018

21 Which row is correct for guanine? has a joins its double ring is a purine complementary base with structure three hydrogen bonds A WA J WA B J x WA Cc x Jv x D x x JY key Y = correct X = incorrect

1 marks

Answer: A

This question in 9700/11 May/June 2018

22 Meselsohn and Stahl investigated DNA in bacteria. They grew bacteria in a medium with only heavy nitrogen, 15N, until all of the bacterial DNA was heavy. These bacteria were moved from a heavy nitrogen medium and cultured in a medium with only light nitrogen, 14N. A sample of bacteria was collected from the first generation in the medium containing light nitrogen and their DNA was analysed. Hybrid DNA contains both heavy and light DNA. Which row shows the percentage of heavy DNA strands and the percentage of hybrid DNA molecules in the first generation produced in the medium containing light nitrogen? percentage of heavy percentage of hybrid DNA strands DNA molecules A 25 50 B 50 50 C 50 100 D 75 100

1 marks

Answer: C

This question in 9700/11 May/June 2018

22 Which statement explains why DNA replication is described as semi-conservative? A Half of each original strand is conserved in each new molecule of DNA. B Half of the base sequence of each strand is conserved in each new molecule of DNA. C Only one strand of DNA is used as a template during replication. D The template for each new molecule of DNA is one strand of the original molecule.

1 marks

Answer: D

This question in 9700/12 May/June 2018

23 A section of a DNA molecule has the coding sequence: AGGCAATGGC. Which statements are correct? 1 This coding sequence contains 3 pyrimidines. 2 The double-stranded DNA of this section contains 26 hydrogen bonds between complementary bases. 3 The double-stranded DNA of this section has 20 sugar-phosphate bonds. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

1 marks

Answer: B

This question in 9700/12 May/June 2018

24 XNA is a laboratory-made nucleic acid made of nucleotides in which one component has been replaced by chemical X. The chemical X is not found in nature. The part of the molecule responsible for coding is not changed. Which organic component of a DNA or RNA nucleotide has been replaced by X? A five-carbon sugar B phosphate group C purine base D pyrimidine base

1 marks

Answer: A

This question in 9700/12 May/June 2018

20 Which row shows the appearance of a chromosome at the beginning of prophase of mitosis and the number of DNA strands in the chromosome? appearance of number of one chromosome DNA strands A 2 B 4 C 1 D 2

1 marks

Answer: B

This question in 9700/13 May/June 2018

22 The diagram shows the outline structure of two nucleotide bases which occur in DNA. This pair is held together by two hydrogen bonds, shown as dashed lines. nucleotide 2 nucleotide 1 Which row correctly identifies these two nucleotide bases? nucleotide 1 nucleotide 2 A adenine thymine B cytosine guanine C guanine cytosine D thymine adenine

1 marks

Answer: A

This question in 9700/13 May/June 2018

23 DNA polymerase catalyses condensation reactions between molecules during semi-conservative replication of DNA. Which two molecules are joined by DNA polymerase? A base and base B base and nucleotide C nucleotide and nucleotide D phosphate and deoxyribose

1 marks

Answer: C

This question in 9700/13 May/June 2018

22 What are the products when a DNA molecule replicates? A two molecules of DNA each made of a paired sequence of bases B two molecules of DNA each made of a paired sequence of nucleotides C two strands of DNA each made of a paired sequence of bases D two strands of DNA each made of a paired sequence of nucleotides

1 marks

Answer: B

This question in 9700/11 Oct/Nov 2018

23 What is the maximum number of hydrogen bonds in a length of DNA containing 700 base pairs? A 350 B 700 C 1400 D 2100

1 marks

Answer: D

This question in 9700/12 Oct/Nov 2018

24 What is the common component of the three molecules RNA, DNA, and ATP? A adenosine B hydrogen bonds C phosphate D ribose

1 marks

Answer: C

This question in 9700/12 Oct/Nov 2018

5 The diagram is a drawing from an electron micrograph of a typical animal cell. 1 2 3 Where would nucleic acid be found? A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

1 marks

Answer: A

This question in 9700/13 Oct/Nov 2018

22 Which bases found in nucleic acids are purines? A adenine and cytosine B guanine and adenine C thymine and cytosine D uracil and guanine

1 marks

Answer: B

This question in 9700/13 Oct/Nov 2018

21 A length of DNA was analysed and sequenced. 24% of its nitrogenous bases were adenine. Which percentage of the bases will be cytosine? A 24 B 26 C 48 D 76

1 marks

Answer: B

This question in 9700/12 Feb/March 2019

22 A short piece of DNA, 19 base pairs long, was analysed to find the number of nucleotide bases in each of the polynucleotide strands. Some of the results are shown below. number of nucleotide bases A C G T strand 1 4 strand 2 7 5 How many nucleotide bases containing C were present in strand 1? A 2 B 3 C 5 D 7

1 marks

Answer: B

This question in 9700/11 May/June 2019

23 Which nucleic acid bases are purines? A adenine and cytosine B cytosine and thymine C guanine and adenine D uracil and cytosine

1 marks

Answer: C

This question in 9700/11 May/June 2019

18 Which statement correctly describes the base pairing in a molecule of DNA? A The purine adenine forms bonds with the pyrimidine thymine. B The purine adenine forms bonds with the pyrimidine uracil. C The purine cytosine forms bonds with the pyrimidine guanine. D The purine guanine forms bonds with the pyrimidine thymine.

1 marks

Answer: A

This question in 9700/12 May/June 2019

19 Which statements about complementary base pairing are correct? 1 It allows translation to occur. 2 Purines and pyrimidines are the same size. 3 The base pairs are of equal length. 4 Uracil forms two hydrogen bonds with adenine. A 1, 2, 3 and 4 B 1, 3 and 4 only C 1 and 4 only D 2 and 3 only

1 marks

Answer: B

This question in 9700/12 May/June 2019

20 The diagram shows the possible organisation of DNA molecules after one replication. Which organisation is correct? one strand of DNA A B C D

1 marks

Answer: C

This question in 9700/12 May/June 2019

21 Some parts of a typical human chromosome are more numerous than others. Which of the parts are listed in order from the most numerous to the least numerous? A centromere, nucleotide, histone B DNA molecule, telomere, centromere C histone, telomere, DNA molecule D telomere, centromere, nucleotide

1 marks

Answer: C

This question in 9700/13 May/June 2019

25 What is the role of DNA polymerase? A condensation reactions to produce DNA nucleotides for replication B correct alignment of RNA nucleotides along a template strand of DNA C formation of bonds to complete the sugar-phosphate backbone D formation of glycosidic bonds between complementary base pairs

1 marks

Answer: C

This question in 9700/13 May/June 2019

26 Which row represents the correct features of the nitrogenous base thymine? has a forms two hydrogen single ring is a purine bonds with its pars with cytosine structure complementary base A v v x x key B Jv x J x / = correct Cc x v x v X = not correct D x x v v

1 marks

Answer: B

This question in 9700/13 May/June 2019

27 Meselson and Stahl investigated DNA in bacteria. They grew bacteria in a medium with only heavy nitrogen, 15N, until all of the bacterial DNA was heavy. These bacteria were moved from a heavy nitrogen medium and cultured in a medium with only light nitrogen, 14N. A sample of bacteria was collected from the second generation and their DNA analysed. Hybrid DNA contains both heavy and light DNA. Which row shows the percentage of heavy DNA strands and the percentage of hybrid DNA molecules in the second generation produced in the medium containing light nitrogen? percentage of heavy percentage of hybrid DNA strands DNA molecules A 25 25 B 25 50 C 50 25 D 50 50

1 marks

Answer: B

This question in 9700/13 May/June 2019

21 Which components could be found in nucleotides of rRNA? 1 any one of two different nitrogenous bases with a double ring structure 2 any one of two different purine bases 3 any one of three different nitrogenous bases with a single ring structure 4 any one of three different pyrimidine bases A 1, 2, 3 and 4 B 1 and 2 only C 1 and 4 only D 3 and 4 only

1 marks

Answer: B

This question in 9700/11 Oct/Nov 2019

22 How many statements are true for semi-conservative replication of DNA in a prokaryotic cell? 1 the process takes place in the cytoplasm 2 an adenine nucleotide will line up against a uracil on the template strand 3 each new DNA molecule will contain one strand from the parent molecule 4 if the parent molecule contained 40% guanine nucleotides each new DNA molecule will contain 20% guanine nucleotides A 1 B 2 C 3 D 4

1 marks

Answer: B

This question in 9700/11 Oct/Nov 2019

23 What is correct for uracil? It joins its It has a single F . complementary ring structure It is a purine base with 2 hydrogen bonds A v v v B v x v Cc x v x D x x v key / = correct X = not correct

1 marks

Answer: B

This question in 9700/12 Oct/Nov 2019

20 The diagram represents a nucleotide containing guanine. base Which statements about this nucleotide are correct? 1 The carbohydrate can be ribose or deoxyribose. 2 Base pairing occurs with three hydrogen bonds. 3 Guanine is a purine. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

1 marks

Answer: A

This question in 9700/13 Oct/Nov 2019

22 Meselson and Stahl investigated DNA in bacteria. They grew bacteria in a medium with only heavy nitrogen, 15N, until all of the bacterial DNA was heavy. These bacteria were moved from a heavy nitrogen medium and cultured in a medium with only light nitrogen, 14N. A sample of bacteria was collected from the first generation and their DNA analysed. Hybrid DNA contains heavy DNA and light DNA. Which row shows the percentage of light DNA strands and the percentage of hybrid DNA molecules in the first generation produced in the medium containing light nitrogen? percentage of light percentage of hybrid DNA strands DNA molecules A 25 50 B 50 50 C 50 100 D 75 100

1 marks

Answer: C

This question in 9700/13 Oct/Nov 2019

4 Which cell structures contain RNA? 1 centrioles 2 mitochondria 3 nucleus 4 ribosomes A 1, 2, 3 and 4 B 1 and 2 only C 2, 3 and 4 only D 3 and 4 only

1 marks

Answer: C

This question in 9700/12 Feb/March 2020

22 What is correct for cytosine? has a single ring is a pyrimidine joins to its complementary base structure with 3 hydrogen bonds A v v v B v x v c x v x D x x v key Y = correct X = incorrect

1 marks

Answer: A

This question in 9700/12 Feb/March 2020

23 Scientists grew bacteria in a medium containing heavy nitrogen, 15N, as the only source of nitrogen. After many generations, both strands of all of the bacterial DNA molecules contained heavy nitrogen. These bacteria were then moved from the heavy nitrogen medium into a medium with only light nitrogen, 14N. The bacteria divided once to form the first generation and once more to form the second generation. A sample of bacteria was collected from the second generation and the DNA was analysed to find: ● the percentage of DNA strands that contained only light nitrogen ● the percentage of DNA molecules that contained light nitrogen and heavy nitrogen. Which row shows the results of this analysis? percentage of DNA strands percentage of DNA molecules that contained only light that contained light nitrogen nitrogen and heavy nitrogen A 50 25 B 50 50 C 75 25 D 75 50

1 marks

Answer: D

This question in 9700/12 Feb/March 2020

20 What is correct for thymine? has a single ring is a pyrimidine joins its complementary base structure with 3 hydrogen bonds A v v v B "4 v x c Y x x D x x v key Y = correct X = incorrect

1 marks

Answer: B

This question in 9700/11 May/June 2020

21 A short piece of DNA 15 base pairs long was analysed to find the number of nucleotide bases in each of the polynucleotide strands. Some of the results are shown below. number of nucleotide bases A C G T strand 1 6 3 strand 2 4 How many nucleotides containing guanine were present in strand 1? A 2 B 3 C 4 D 6

1 marks

Answer: A

This question in 9700/11 May/June 2020

22 Scientists grew bacteria in a medium containing heavy nitrogen, 15N, as the only source of nitrogen. After many generations, all of the bacterial DNA contained heavy nitrogen. These bacteria were then moved from the heavy nitrogen medium into a medium with only light nitrogen, 14N. Some bacteria were collected from each of the next three generations and their DNA was analysed. Hybrid DNA contains both heavy and light nitrogen. Which row shows the correct DNA of the first and third generations? DNA of first generation DNA of third generation A all hybrid half hybrid, half light B all hybrid one quarter hybrid, three quarters light C half hybrid, half heavy half hybrid, one quarter heavy, one quarter light D half hybrid, half light one quarter hybrid, three quarters light

1 marks

Answer: B

This question in 9700/11 May/June 2020

23 A population of bacteria is exposed to the antibiotic penicillin. Most of the bacteria die. However, some bacteria in the population have an allele coding for an enzyme that breaks down penicillin. These bacteria are able to survive. Which could explain how these bacterial cells acquired this allele? 1 An error during DNA replication. 2 An error during transcription. 3 An error during translation. A 1, 2 and 3 B 1 and 3 only C 1 only D 2 and 3 only

1 marks

Answer: C

This question in 9700/11 May/June 2020

19 Which description of chromosome structure is correct? A A chromosome at the beginning of interphase consists of two identical chromatids, each containing one linear molecule of DNA. B Telomeres are lengths of non-coding DNA found at one end of each chromatid to prevent loss of genes during cell division. C The two identical chromatids of a chromosome are held together by a centromere in which there is no DNA. D The very long DNA molecule of each chromatid is coiled and held together by proteins called histones.

1 marks

Answer: D

This question in 9700/12 May/June 2020

22 Some viruses have single-stranded DNA as their genetic material. This DNA molecule has to be folded to fit in the protein coat. Which statements about single-stranded DNA are correct? 1 Single-stranded DNA cannot replicate semi-conservatively. 2 If only the percentage of cytosine is known, then the percentage of guanine can be calculated, but the percentage of adenine and thymine cannot be calculated. 3 Hydrogen bonds may be present within the DNA molecule. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

1 marks

Answer: C

This question in 9700/12 May/June 2020

23 How many statements are true for semi-conservative replication of DNA in a eukaryotic cell? 1 The process takes place in the nucleus. 2 Adenine will line up against uracil on the complementary strand. 3 Each new molecule will contain one strand of the original molecule. 4 If the original molecule contained 40% guanine each new molecule will contain 20% guanine. A 1 B 2 C 3 D 4

1 marks

Answer: B

This question in 9700/12 May/June 2020

19 Scientists have made a nucleic acid, HNA, that has a sugar with the same number of carbon atoms as glucose instead of deoxyribose. Although genetic information can be stored by HNA, naturally occurring DNA polymerase cannot replicate HNA. Which statements could explain why naturally occurring DNA polymerase cannot replicate HNA? 1 DNA polymerase cannot form bonds between the sugars of two HNA nucleotides. 2 DNA polymerase cannot form hydrogen bonds between two HNA nucleotides. 3 HNA nucleotides do not fit into the active site of DNA polymerase. 4 The shape of an HNA nucleotide is slightly larger than that of a DNA nucleotide. A 1, 2, 3 and 4 B 1 and 4 only C 2 and 3 only D 3 and 4 only

1 marks

Answer: D

This question in 9700/13 May/June 2020

20 Which statements about the nucleotide containing uracil are correct? 1 Uracil is a pyrimidine. 2 The carbohydrate is always ribose. 3 Base pairing occurs with 3 hydrogen bonds. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

1 marks

Answer: B

This question in 9700/13 May/June 2020

21 DNA replication involves several stages. 1 Each strand of DNA double helix acts as a template for the opposite strand. 2 The enzyme DNA polymerase links bases together. 3 Hydrogen bonds between bases A and T and between C and G are broken. Which statements about DNA replication are correct? A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 3 only

1 marks

Answer: C

This question in 9700/13 May/June 2020

21 The diagram represents a nucleotide containing cytosine. base Which statements about this nucleotide are correct? 1 The carbohydrate could be ribose. 2 The organic base contains nitrogen. 3 Base pairing occurs with guanine. 4 Cytosine is a purine. A 1, 2 and 3 B 1, 2 and 4 C 1, 3 and 4 D 2, 3 and 4

1 marks

Answer: A

This question in 9700/11 Oct/Nov 2020

22 A section of DNA contains 73 base pairs. number of bases on each strand adenine cytosine guanine thymine strand 1 29 V 14 W strand 2 21 X Y Z Which row represents the correct number of bases? V W X Y Z A 9 21 14 9 29 B 14 29 9 9 21 C 21 9 29 9 14 D 29 9 29 14 9

1 marks

Answer: A

This question in 9700/11 Oct/Nov 2020

22 Which row represents the correct features of guanine? joins its has a ; . . : . . complementary pairs with single ring IS @ purine base via three thymine structure hydrogen bonds A v Jv x v B v x v x Cc x Jv v x D x x v v key / = correct X = not correct

1 marks

Answer: C

This question in 9700/13 Oct/Nov 2020

23 Bacteria were grown in a medium containing 15N. After several generations, all of the DNA contained 15N. Some of these bacteria were transferred to a medium containing the common isotope of nitrogen, 14N. The bacteria were allowed to divide once. The DNA of some of these bacteria was extracted and analysed. This DNA was all hybrid DNA containing equal amounts of 14N and 15N (14N / 15N). In another experiment, some bacteria from the medium with 15N were transferred into a medium of 14N. The bacteria were allowed to divide three times. The DNA of some of these bacteria was extracted and analysed. What is the composition of this DNA? A B 100 100 75 75 percentage percentage 50 50 of DNA of DNA 25 25 0 0 14N 14N / 15N 14N 14N / 15N C D 100 100 75 75 percentage percentage 50 50 of DNA of DNA 25 25 0 0 14N 14N / 15N 14N 14N / 15N

1 marks

Answer: C

This question in 9700/13 Oct/Nov 2020

22 Which statements about complementary base pairing are correct? 1 Cytosine forms two hydrogen bonds with guanine. 2 Purines and pyrimidines are different sizes. 3 Adenine forms the same number of hydrogen bonds with thymine as it does with uracil. 4 The base pairs in a molecule of DNA are of equal length and equal width. A 1, 2 and 3 B 1, 2 and 4 C 1, 3 and 4 D 2, 3 and 4

1 marks

Answer: D

This question in 9700/12 Feb/March 2021

23 What are the products when a DNA molecule replicates? A two molecules of DNA each made of a sequence of paired bases B two molecules of DNA each made of a sequence of paired nucleotides C two strands of DNA each made of a sequence of paired bases D two strands of DNA each made of a sequence of paired nucleotides

1 marks

Answer: B

This question in 9700/12 Feb/March 2021

20 Four nucleotides, A, B, C and D, each consist of three phosphate groups, a nitrogenous base and a pentose sugar. Characteristics of the base and sugar components before they are joined to form each nucleotide are shown in the table. Which nucleotide could pair with an adenine base during DNA replication? ratio of carbon to ring structure of oxygen atoms in nitrogenous base pentose sugar A double 1 : 1 B double 5 : 4 C single 1 : 1 D single 5 : 4

1 marks

Answer: D

This question in 9700/11 May/June 2021

17 Human chromosomes have different parts. Some parts are more numerous than others. Which parts are listed in order from most numerous to least numerous in a human white blood cell? A centromere  nucleotide  histone protein B DNA molecule  telomere  centromere C histone protein  telomere  DNA molecule D telomere  centromere  nucleotide

1 marks

Answer: C

This question in 9700/12 May/June 2021

20 A short piece of DNA, 18 base pairs long, was analysed to find the number of nucleotide bases in each of the polynucleotide strands. Some of the results are shown in the table. number of nucleotide bases adenine cytosine guanine thymine strand 1 4 7 strand 2 5 How many nucleotides containing thymine were present in strand 2? A 2 B 4 C 5 D 7

1 marks

Answer: A

This question in 9700/12 May/June 2021

21 The diagram shows a strand of DNA and mRNA during transcription. 1 2 P C G P P G C P 3 Which row correctly identifies 1, 2 and 3? 1 2 3 A purine deoxyribose two hydrogen bonds B purine ribose three hydrogen bonds C pyrimidine deoxyribose two hydrogen bonds D pyrimidine ribose three hydrogen bonds

1 marks

Answer: D

This question in 9700/12 May/June 2021

22 Two students were discussing the involvement of DNA and RNA in transcription and translation.  Student 1 always stated correct facts.  Student 2 gave further information, which was sometimes correct. correct facts given by student 1 further information given by student 2 1 A length of mRNA is 747 nucleotides This mRNA can produce a polypeptide long, including stop and start codons. that is 249 amino acids long. 2 Adjacent mRNA codons of AAU There is a total of 14 hydrogen bonds and CUG bind to complementary formed between these two codons and tRNA anticodons. their anticodons. 3 RNA polymerase catalyses the formation During translation, an RNA adenine of the mRNA from the template strand nucleotide will pair with a DNA thymine of DNA. nucleotide. 4 A DNA adenine nucleotide is structurally The difference is in the hexose sugars; different to an RNA adenine nucleotide. DNA is deoxyribose and RNA is ribose. Which further information, given by student 2, is correct? A 1 and 4 B 2 and 3 C 2 only D 4 only

1 marks

Answer: C

This question in 9700/12 May/June 2021

20 The diagram represents a nucleotide containing thymine. base Which statements about this nucleotide are correct? 1 Thymine is a pyrimidine. 2 Base pairing occurs with two hydrogen bonds. 3 The carbohydrate can be ribose or deoxyribose. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

1 marks

Answer: B

This question in 9700/13 May/June 2021

4 Which rows could correctly identify the nucleic acids present in two different virus particles in a sample of air? A 1 and 2 DNA RNA 1 v v key 2 Jv x ¥ = nucleic acid present 3 x Jv X = nucleic acid not present 4 x x B 1and3 C 2and3 D 3and4

1 marks

Answer: C

This question in 9700/11 Oct/Nov 2021

21 Which statement helps to explain why the two sugar-phosphate chains in a DNA molecule are a constant distance apart? A Adenine and thymine are held together by the same number of hydrogen bonds as cytosine and guanine. B Each nucleotide molecule is the same size. C Each purine base is linked to a pyrimidine base. D The sugar-phosphate strands of the helix are held together by sulfur bridges.

1 marks

Answer: C

This question in 9700/11 Oct/Nov 2021

22 During DNA replication, what must happen before a newly added nucleotide is bonded to the next nucleotide in the strand? 1 complementary base pairing 2 hydrogen bond formation 3 phosphodiester bond formation A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

1 marks

Answer: B

This question in 9700/11 Oct/Nov 2021

22 A piece of a DNA molecule contains 84 base pairs. The table shows the number of adenine and cytosine bases in one or both of the DNA strands in this piece of DNA molecule. base strand 1 strand 2 adenine 28 23 cytosine 15 How many guanine bases are present in this piece of DNA molecule? A 18 B 33 C 36 D 41

1 marks

Answer: B

This question in 9700/12 Oct/Nov 2021

18 Which row shows the correct number of each component of a single chromatid during anaphase of mitosis? polynucleotide centromeres telomeres strands A 1 2 2 B 1 4 4 C 2 2 4 D 2 4 2

1 marks

Answer: A

This question in 9700/13 Oct/Nov 2021

21 Which letter in the key describes uracil? is a purine yes no is found has a single in RNA ring structure yes no yes no A B C D

1 marks

Answer: C

This question in 9700/13 Oct/Nov 2021

4 Which eukaryotic cell structures all contain nucleic acids? A cytoplasm, Golgi bodies, mitochondria, nuclei B centrioles, chloroplasts, mitochondria, ribosomes C centrioles, mitochondria, nuclei, ribosomes D chloroplasts, mitochondria, cytoplasm, ribosomes

1 marks

Answer: D

This question in 9700/12 Feb/March 2022

21 Some parts of a typical human chromosome are more numerous than others. Which parts are listed in order from the most numerous to the least numerous? A centromere, nucleotide, histone B DNA molecule, telomere, centromere C histone, telomere, DNA molecule D telomere, centromere, nucleotide

1 marks

Answer: C

This question in 9700/12 Feb/March 2022

23 The diagram represents a nucleotide containing adenine. base Which statements about this nucleotide are correct? 1 The carbohydrate is a pentose. 2 The base contains nitrogen. 3 Base pairing occurs with uracil. 4 Adenine is a pyrimidine. A 1, 2, 3 and 4 B 1, 2 and 3 only C 1 and 2 only D 3 and 4 only

1 marks

Answer: B

This question in 9700/12 Feb/March 2022

24 Which row is correct for the replication of a DNA molecule? enzyme that adds direction of DNA complementary nucleotides to synthesis lagging strand A 3′ to 5′ DNA polymerase B 3′ to 5′ DNA ligase C 5′ to 3′ DNA polymerase D 5′ to 3′ DNA ligase

1 marks

Answer: C

This question in 9700/12 Feb/March 2022

22 Bacterial cells with DNA containing only the ‘heavy’ isotope of nitrogen (15N) are allowed to reproduce for three generations in a culture medium containing the normal isotope of nitrogen (14N). Which percentage of the DNA molecules produced contain strands with the heavy isotope of nitrogen? first generation second generation third generation % % % A 50 25 12.5 B 75 50 25 C 100 50 25 D 100 75 50

1 marks

Answer: C

This question in 9700/11 May/June 2022

23 A bacterial circular DNA molecule is 2 600 150 base pairs long. 26% of the bases are adenine. How many cytosine bases would be in the DNA molecule? A 624 036 B 676 039 C 1 248 072 D 1 352 078

1 marks

Answer: C

This question in 9700/11 May/June 2022

24 Which statement relating to the structure of DNA is correct? A Two DNA strands are joined to each other by phosphodiester bonds. B The alignment of bases to form a double helix is only achieved between antiparallel strands. C Three hydrogen bonds are formed between all base pairs containing purines. D The number of cytosine bases always equals the number of thymine bases.

1 marks

Answer: B

This question in 9700/11 May/June 2022

18 Telomeres prevent the loss of genes from the ends of chromosomes during DNA replication, but they become shorter each time they are copied. In cancer cells and stem cells, the telomeres remain the same length. Which statement is correct for all human cells? A If telomeres become too short, a cell may stop dividing. B Adding telomeres could increase the rate of ageing of cells. C Telomeres are repaired by the enzyme RNA polymerase. D Telomeres prevent all damage occurring to DNA molecules.

1 marks

Answer: A

This question in 9700/12 May/June 2022

19 The nucleus of a mouse body cell in G1 phase of the cell cycle has 1.2  10–12 g of DNA. What will be the mass of DNA in the nucleus of the cell at the end of S phase and at the end of G2 phase of the cell cycle? end of S phase end of G2 phase A 1.2  10–12 g 1.2  10–12 g B 1.2  10–12 g 2.4  10–12 g C 2.4  10–12 g 1.2  10–12 g D 2.4  10–12 g 2.4  10–12 g

1 marks

Answer: D

This question in 9700/12 May/June 2022

21 Which statement describes the structure of ATP? A It is a DNA nucleotide with two extra phosphates. B It is a DNA nucleotide with three extra phosphates. C It is an RNA nucleotide with two extra phosphates. D It is an RNA nucleotide with three extra phosphates.

1 marks

Answer: C

This question in 9700/12 May/June 2022

24 The diagram shows part of a DNA molecule. O H3C O O D N O H O N O H N H O O P O– N O O N C O– P O N N N O O N O O O H H A N N N O– O P H O N O N O– P O B H H O N O O O O O P O– O O O– P O O Which label is correct? A adenine B guanine C cytosine D thymine

1 marks

Answer: D

This question in 9700/13 May/June 2022

22 Which nitrogenous bases are pyrimidines? A adenine and thymine B cytosine and guanine C thymine and uracil D uracil and guanine

1 marks

Answer: C

This question in 9700/11 Oct/Nov 2022

23 DNA replication in bacteria was investigated. Bacteria were grown in a medium with only heavy nitrogen, 15N, until all of the bacterial DNA was heavy. These bacteria were moved from the heavy nitrogen medium and cultured in a medium with only light nitrogen, 14N. This formed the first generation. The bacteria continued to reproduce, and a sample of bacteria was collected from the second generation and the DNA analysed. Hybrid DNA contains heavy and light DNA. Which row is correct for the second generation? percentage of heavy percentage of hybrid DNA strands DNA molecules A 25 25 B 25 50 C 50 25 D 50 50

1 marks

Answer: B

This question in 9700/11 Oct/Nov 2022

5 Which molecules are present in all viruses? 1 thymine 2 adenine 3 cytosine A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

1 marks

Answer: D

This question in 9700/12 Oct/Nov 2022

22 How many statements about semi-conservative replication of DNA in a eukaryotic cell are correct? 1 The process takes place in the cytoplasm. 2 An adenine nucleotide will line up against uracil on the template strand. 3 Each daughter molecule will contain half of the original DNA molecule. 4 If the DNA molecule contained 40% guanine nucleotides, each daughter molecule will contain 20% guanine nucleotides. A 1 B 2 C 3 D 4

1 marks

Answer: A

This question in 9700/12 Oct/Nov 2022

19 The photomicrographs show cells in various stages of the cell cycle. In which stage does semi-conservative replication of DNA take place? A B C D

1 marks

Answer: C

This question in 9700/13 Oct/Nov 2022

22 What does a nucleotide contain? 1 an amino acid 2 a codon 3 a nitrogenous base 4 a sugar A 1 and 2 B 1 and 4 C 2 and 3 D 3 and 4

1 marks

Answer: D

This question in 9700/13 Oct/Nov 2022

23 A diagram can be used to show some relationships between different nucleic acid bases. 1 2 3 4 5 Which row is correct for the words that can be placed at positions 1–5? 1 2 3 4 5 A adenine purine cytosine pairs with guanine B cytosine purine guanine pairs with uracil C guanine pairs with cytosine pyrimidine thymine D thymine pairs with uracil pyrimidine adenine

1 marks

Answer: C

This question in 9700/13 Oct/Nov 2022

24 The bacterium Escherichia coli divides once every 50 minutes at 36 °C. E. coli were grown on a medium containing only heavy nitrogen, 15N, until all of the bacterial DNA contained heavy nitrogen. Some of the bacteria were moved from a heavy nitrogen medium and cultured in a medium with only light nitrogen, 14N (0 minutes). These bacteria continued to reproduce and samples were extracted and centrifuged at regular intervals. Hybrid DNA contains both heavy and light nitrogen. The diagram shows the possible positions (upper, middle and lower) of the bands of DNA. The actual positions of bands in the first two samples are shown. upper upper middle middle lower lower 0 50 100 150 sample time: minutes minutes minutes minutes Which proportion of the DNA of the sample taken at 150 minutes will be at the upper position? A 25% B 50% C 75% D 100%

1 marks

Answer: C

This question in 9700/13 Oct/Nov 2022

21 DNA polymerase catalyses condensation reactions between molecules during semi-conservative replication of DNA. What is joined by DNA polymerase? A base and base B base and nucleotide C nucleotide and nucleotide D phosphate and ribose

1 marks

Answer: C

This question in 9700/12 Feb/March 2023

22 Two polynucleotide strands make up a DNA molecule. Which description is correct? A The percentage of cytosine is 50% of that of guanine in the whole molecule. B The percentage of cytosine is the same as that of guanine in the whole molecule. C The percentage of cytosine is the same as that of guanine in each strand. D The percentage of cytosine is the same in each strand of the molecule.

1 marks

Answer: B

This question in 9700/12 Feb/March 2023

23 The PDx1 protein is found in a wide range of animal species where it is regarded as essential for normal metabolism. In sand rats, the gene coding for the PDx1 protein has a much lower proportion of A and T nucleotides than PDx1 genes from other animals. Finding the complete DNA sequence of the PDx1 gene in sand rats has been difficult. Sequencing involves splitting off nucleotides one at a time from single-stranded DNA. What could account for the difficulty in finding the DNA sequence of the PDx1 gene in sand rats? 1 The PDx1 gene is present in only a small proportion of nuclei. 2 The PDx1 gene is transcribed in only some cells. 3 The strength of the hydrogen bonding between the two strands of the PDx1 gene is unusually high. A 1, 2 and 3 B 1 only C 2 only D 3 only

1 marks

Answer: D

This question in 9700/12 Feb/March 2023

7 What is present in all viruses, all prokaryotes and all eukaryotes? A ribose B deoxyribose C cytosine D thymine

1 marks

Answer: C

This question in 9700/11 May/June 2023

6 Which polymers are present in all viruses and all prokaryotes? 1 polynucleotides 2 polypeptides 3 polysaccharides A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

1 marks

Answer: B

This question in 9700/12 May/June 2023

23 Which molecules make up the structure of ATP? 1 adenine 2 thymine 3 deoxyribose 4 phosphate 5 ribose A 1, 2 and 3 B 1, 3 and 4 C 1, 4 and 5 D 2, 4 and 5

1 marks

Answer: C

This question in 9700/13 May/June 2023

24 A short piece of DNA, 19 base pairs long, was analysed to find the number of nucleotide bases in each of the polynucleotide strands. Some of the results are shown. number of nucleotide bases A C G T strand 1 4 strand 2 7 5 How many cytosines were in strand 1? A 2 B 3 C 5 D 7

1 marks

Answer: B

This question in 9700/13 May/June 2023

25 Which statement about the role of DNA polymerase in the process of semi-conservative replication of DNA is correct? A DNA polymerase forms the hydrogen bonds between complementary base pairs. B DNA polymerase moves along the lagging strand in the 3′ to 5′ direction. C DNA polymerase joins new bases to the leading strand only. D DNA polymerase moves along leading and lagging strands in the 5′ to 3′ direction.

1 marks

Answer: D

This question in 9700/13 May/June 2023

7 Which bonds are present in all viruses? 1 phosphodiester 2 peptide 3 covalent A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

1 marks

Answer: A

This question in 9700/12 Oct/Nov 2023

21 Which statement correctly describes a feature of a DNA molecule? A It has two parallel strands twisted into a double helix. B It has complementary bases all held together by three hydrogen bonds. C It has phosphodiester bonds that are formed using DNA ligase. D It has a backbone of phosphate molecules and nucleotides.

1 marks

Answer: C

This question in 9700/12 Oct/Nov 2023

22 Which diagram correctly shows the replication of DNA? A B 5′ 5′ S2 S1 3′ 3′ 5′ 5′ S1 S2 3′ 3′ C D 5′ 5′ S2 S1 3′ 3′ 5′ 5′ S1 S2 3′ 3′ key direction of replication S1 leading strand S2 lagging strand

1 marks

Answer: C

This question in 9700/12 Oct/Nov 2023

6 Which cell organelle does not have nucleic acids? A chloroplast B Golgi body C mitochondrion D ribosome

1 marks

Answer: B

This question in 9700/13 Oct/Nov 2023

8 Which bonds are present in all viruses? 1 covalent 2 ester 3 phosphodiester A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

1 marks

Answer: C

This question in 9700/13 Oct/Nov 2023

22 During lagging strand replication, short fragments of DNA are produced. The fragments are joined together by DNA ligase. Which row correctly describes the structure of these short fragments of DNA? have base sequences that are complementary : carbon, hydrogen, to the newly synthesised polyns cleotide oxygen and leading DNA strand nitrogen contains only consists of one key JY = correct X = not correct

1 marks

Answer: D

This question in 9700/13 Oct/Nov 2023

24 40% of the bases in a section of a non-transcribed strand of DNA are purine molecules. What will be the total percentage of cytosine and uracil bases in the primary transcript that is transcribed from the other strand of the DNA? A 20% B 30% C 40% D 60%

1 marks

Answer: D

This question in 9700/13 Oct/Nov 2023

23 Which statements are correct for all nucleotides? 1 The nitrogen-containing base is always attached to carbon atom 1 of the pentose. 2 The phosphate group is always attached to carbon atom 5 of the pentose. 3 A condensation reaction occurs to join the nitrogen-containing base to the pentose. 4 Nucleotides are linked together by condensation reactions between phosphate groups. A 1, 2 and 3 B 1 and 2 only C 1, 3 and 4 D 2, 3 and 4

1 marks

Answer: A

This question in 9700/12 Feb/March 2024

24 How many phosphodiester bonds are present in a circular DNA molecule of 2700 base pairs? A 2699 B 2700 C 5398 D 5400

1 marks

Answer: D

This question in 9700/12 Feb/March 2024

25 Which statements about complementary base pairing are correct? 1 Purines and pyrimidines are different sizes. 2 Complementary base pairing occurs during translation. 3 The base pairs are of different lengths. 4 Uracil forms two hydrogen bonds with adenine. A 1, 2 and 3 B 1, 2 and 4 C 1, 3 and 4 D 2, 3 and 4

1 marks

Answer: B

This question in 9700/12 Feb/March 2024

26 During the mitotic cell cycle, the chromosomal DNA is replicated. The specific points in DNA molecules where replication is occurring are known as replication forks. A typical human chromosome has about 150 million base pairs of DNA. It takes about 1 hour to replicate the DNA of a typical human chromosome. The rate of replication using a single replication fork is approximately 50 base pairs per second. Approximately how many replication forks must occur in a typical human chromosome during DNA replication? A 835 B 41 700 C 50 000 D 3 000 000

1 marks

Answer: A

This question in 9700/12 Feb/March 2024

21 The diagrams show the chemical structure of four bases. NH2 O C C CH3 N HN C C N HC C CH C CH N N N O H H 1 2 NH2 O C C N CH N NH C HC C CH C C O N N N NH2 H H 3 4 Which diagrams show thymine and cytosine? A 1 and 2 B 1 and 4 C 2 and 3 D 3 and 4

1 marks

Answer: C

This question in 9700/11 May/June 2024

22 Which bond formation does DNA polymerase catalyse? A hydrogen bonds between bases B hydrogen bonds between nucleotides C phosphodiester bonds between bases D phosphodiester bonds between nucleotides

1 marks

Answer: D

This question in 9700/12 May/June 2024

21 During the semi-conservative replication of DNA, the double helix is unwound by an enzyme. Which diagram shows how the strands are copied? A B 3′ 5′ 3′ 5′ 5′ 5′ DNA 3′ DNA 3′ polymerase polymerase lagging leading strand strand DNA DNA ligase 3′ ligase 3′ 5′ 3′ 5′ 5′ 3′ 5′ leading strand lagging strand C D 5′ 3′ 5′ 3′ 3′ 3′ DNA 5′ DNA 5′ polymerase polymerase lagging leading strand strand DNA DNA ligase 5′ ligase 5′ 3′ 5′ 3′ 3′ 5′ 3′ leading strand lagging strand

1 marks

Answer: D

This question in 9700/13 May/June 2024

22 Which row about the stages of the mitotic cell cycle is correct? RNA polymerase DNA ligase used used in the in the nucleus nucleus A G1 phase S phase B G2 phase mitosis C mitosis G2 phase D S phase G1 phase

1 marks

Answer: D

This question in 9700/11 Oct/Nov 2024

26 How many hydrogen bonds form when adenine and cytosine each bind to their complementary bases? adenine cytosine A 2 2 B 2 3 C 3 2 D 3 3

1 marks

Answer: B

This question in 9700/11 Oct/Nov 2024

23 The diagram shows a section of a strand of DNA. X Which type of bond is labelled X? A glycosidic B hydrogen C peptide D phosphodiester

1 marks

Answer: D

This question in 9700/12 Oct/Nov 2024

24 Which row correctly describes cytosine? number of hydrogen ring structure bonds it forms with its type of base complementary base A double three purine B double two pyrimidine C single three pyrimidine D single two purine

1 marks

Answer: C

This question in 9700/12 Oct/Nov 2024

21 The diagram shows part of a nucleic acid molecule. A X G U C What is the name of bond X? A glycosidic bond B hydrogen bond C peptide bond D phosphodiester bond

1 marks

Answer: D

This question in 9700/13 Oct/Nov 2024

22 XNA is a laboratory-made nucleic acid. XNA is made of nucleotides in which one component has been replaced by chemical X. The chemical X is organic but is not found in nature. The part of the molecule responsible for coding is not changed. Which component of a DNA or RNA nucleotide has been replaced by the organic chemical X? A five-carbon sugar B phosphate group C purine base D pyrimidine base

1 marks

Answer: A

This question in 9700/13 Oct/Nov 2024

19 A nucleus in a body cell of a species of fruit fly has 8 chromosomes. How many strands of DNA are present in the nucleus at the end of interphase? A 8 B 16 C 32 D 64

1 marks

Answer: C

This question in 9700/12 Feb/March 2025

24 Which diagram correctly represents one of the base pairs of DNA? A B P A T P P C G P C D P C G P P A T P

1 marks

Answer: B

This question in 9700/12 Feb/March 2025

22 During which phase of the cell cycle does DNA replication take place? A G1 B G2 C M D S

1 marks

Answer: D

This question in 9700/12 May/June 2025

24 Sometimes hydrogen bonds form temporarily between the bases of two strands of RNA. How many hydrogen bonds form when guanine and uracil each bind to their complementary base? guanine uracil A 3 3 B 3 2 C 2 3 D 2 2

1 marks

Answer: B

This question in 9700/12 May/June 2025

8 Which statement about a macromolecule is correct? A Amylose is a branched polymer made of -glucose and -glucose monomers. B DNA is an association of two polymers made of nucleotide monomers. C Haemoglobin is an association of four polymers made up of monomers of haem groups and amino acids. D Triglycerides are polymers made of fatty acids and glycerol.

1 marks

Answer: B

This question in 9700/13 May/June 2025

25 What correctly identifies the number and type of bonds between cytosine and guanine in a DNA molecule? A 2 hydrogen bonds B 2 phosphodiester bonds C 3 hydrogen bonds D 3 phosphodiester bonds

1 marks

Answer: C

This question in 9700/13 May/June 2025

22 What is the role of telomeres? A allowing the chromatids to reach the poles during mitosis B holding sister chromatids together C making sure that the sister chromatids are of identical length D preventing loss of genes during DNA replication

1 marks

Answer: D

This question in 9700/14 May/June 2025

24 DNA forms a leading strand and a lagging strand during semi-conservative replication. Which row correctly matches the strands to their properties? the strand that is replicated by joining the strand that together short requires DNA ligase sequences of DNA in a 3′ to 5′ direction A lagging lagging B lagging leading C leading leading D leading lagging

1 marks

Answer: A

This question in 9700/14 May/June 2025

23 The diagram shows a section of DNA. Two of the bases in this section are labelled 1 and 2. O 1 O O O O O 2 Which row correctly identifies the bases 1 and 2? base 1 base 2 A purine adenine B purine guanine C pyrimidine adenine D pyrimidine guanine

1 marks

Answer: B

This question in 9700/11 Oct/Nov 2025

24 Which row describes the role of the enzymes DNA polymerase and DNA ligase? DNA polymerase DNA ligase A adds nucleotides in joins sections of DNA together a 5′ to 3′ direction on the lagging strand B adds nucleotides in joins sections of DNA together a 3′ to 5′ direction on the leading strand C adds nucleotides in joins sections of DNA together a 3′ to 5′ direction on the lagging strand D adds nucleotides in joins sections of DNA together a 5′ to 3′ direction on the leading strand

1 marks

Answer: A

This question in 9700/11 Oct/Nov 2025

24 The diagram represents a molecule of ATP. J K L What are the components of ATP labelled J, K and L? J K L A adenine deoxyribose phosphates B adenosine pentose a phosphate group C adenosine ribose phosphorus D purine pentose phosphates

1 marks

Answer: D

This question in 9700/13 Oct/Nov 2025

25 Which statements about complementary base pairing are correct? 1 It occurs during translation. 2 Purines and pyrimidines are the same size. 3 The base pairs are of equal length. 4 Uracil forms three hydrogen bonds with adenine. A 1 and 2 B 1 and 3 C 2 and 3 D 3 and 4

1 marks

Answer: B

This question in 9700/13 Oct/Nov 2025