IBBiology: SLDPExam Questions3. Genetics3.1 Genes & Chromosomes

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First teaching 2014

Last exams 2024

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Genes & Chromosomes (DP IB Biology: SL)

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3.1 Genes & Chromosomes

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3.1 Genes & Chromosomes

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11 mark

Which of the following statements about genomes is not correct? 

  • Humans have around 20 000 genes

  • Species vary in the number of genes they have

  • The number of genes of an organism is not proportional to genome size

  • Humans have the most genes of any organism

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21 mark

Which option correctly completes the sentence below?

Multiple alleles are present _________.

  • At the same locus on homologous chromosomes

  • At different loci on different chromosomes

  • At different loci on the same chromosome

  • On sister chromatids

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31 mark

Which of the following statements, correctly describes the impact of the substitution mutation shown below?

Y623Ljwi_e-3

  • The codon encoding an amino acid was changed to a stop codon, truncating the polypeptide

  • The sequence of amino acids may code for a different protein structure

  • The resulting polypeptide chain will be elongated

  • There will be no change in the polypeptide chain

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41 mark

Which row correctly describes the features of prokaryotic chromosomal DNA?

A. Associated with histone proteins Circular
B. Not associated with histone proteins Linear
C. Not associated with histone proteins Circular
D. Contains a few hundred genes  Circular

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    51 mark

    Which of the individuals below is represented by the following karyogram?

    fPz8KBpJ_e-5

    • A male with a chromosomal abnormality

    • A genetically normal female

    • A male with Down syndrome

    • A female with Down syndrome

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    11 mark

    Which of the following statements about genes is not correct?

    • A gene may be found at a different locus in different individuals.

    • A gene is a section of DNA that codes for one polypeptide.

    • Genes are heritable factors.

    • The number of genes that a species has is not directly proportional to the size or complexity of the organism.

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    21 mark

    Which of the following statements about alleles are correct?

    1. New alleles can arise through mutation.
    2. There are two different versions, or alleles, of every gene.
    3. Every eukaryotic cell contains two alleles of every gene.

    • I only

    • I and II only

    • I and III only

    • II and III only

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    31 mark

    Sickle cell anaemia is caused by the following mutation in the gene that codes for haemoglobin:

    3-1-biology-q3-ib-hl

    Which of the following correctly explains how this mutation causes sickle cell anaemia?

    • It causes valine to be replaced by glutamic acid, altering the structure of the haemoglobin protein.

    • It produces an allele known as HbA.

    • It causes glutamic acid to be replaced by valine, altering the structure of the final haemoglobin protein.

    • It causes an amino acid substitution at the 8th position in the polypeptide.

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    41 mark

    Which of the following statements about genome sequencing are correct?
     

    A

    Scientists now know the location and role of every human gene

    The genomes of humans are the only genomes to be sequenced in their entirety

    Advancing computer technology means that the rate at which a genome can be sequenced continues to increase

    B

    Scientists can now look for correlations between changes in a gene and particular human traits

    The genomes of humans are the only genomes to be sequenced in their entirety

    Genome sequencing technology is now so advanced that further developments are not expected

    C

    Scientists can now look for correlations between changes in a gene and particular human traits

    The genomes of many species have now been sequenced

    Advancing computer technology means that the rate at which a genome can be sequenced continues to increase

    D

    Scientists can now look for correlations between changes in a gene and particular human traits

    The genomes of many species have now been sequenced

    Genome sequencing technology is now so advanced that further developments are not expected

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      51 mark

      John Cairns carried out a study in which he kept E. coli bacteria in a solution containing radioactive thymine. 

      What was he able to conclude from the results of his study?

      • Prokaryotes have a circular chromosome.

      • E. coli have a circular chromosome.

      • Autoradiography does not produce clear enough results to determine whether bacteria have one chromosome or many.

      • Bacteria replicate their DNA using a structure called a replication fork.

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      61 mark

      Which of the following statements about eukaryotic chromosomes are correct? 

      1. Chromosomes are long, linear molecules that can be condensed for compact storage.
      2. After DNA replication, the two strands of DNA are held together at the centromere.
      3. DNA wraps around histone proteins to form chromatids.

      • I and II only

      • II only

      • II and III only

      • I, II, and III

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      71 mark

      The diagram below shows a plant life cycle. It includes unfamiliar stages such as ‘sporophyte’ and ‘gametophyte’ that are not found in human life cycles.

      biology-3-1-q7-ib-hl

      What process is taking place at the stage marked X on the diagram? 

      • Fertilisation

      • Meiosis

      • Fusion 

      • Mitosis

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      81 mark

      Which of the following explains why the father determines the sex of offspring and not the mother?

      • Only sperm cells contain the sex chromosomes.

      • Mothers can only pass on the Y chromosome to their offspring.

      • Females can only pass on the X chromosome to their offspring.

      • Female gametes only contain autosomes.

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      91 mark

      Which of the individuals described below does the following karyogram represent?

      biology-3-1-q9-ib-hl

      • A male with Down syndrome.

      • A male with a chromosome abnormality.

      • A healthy male.

      • A female with Down syndrome.

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      101 mark

      Which of the following is not correct regarding online gene databases?

      • Online databases can be used to find the locus of a human gene.

      • Online databases can be used to find out the chromosome on which a gene is located.

      • Online databases can be used to determine the evolutionary relationships of organisms.

      • Online databases can only be used by scientists with special access.

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      1
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      The nucleotide base sequence and the associated sequence of four amino acids can be seen below:

      AGG   ACA   CCT   GGA

      Serine   Tyrosine   Glycine   Proline

      The table shows the mRNA codons and their associated amino acids.

      h-1

      A single mutation occurred in the original base sequence of the DNA which resulted in only one amino acid from the sequence being produced.

      Which of the following would represent the correct nucleotide base sequence which was found in the DNA after the mutation occurred?

      • AGT   ACA   CCT   GGA

      • AGG   ACT   CCT   GGA

      • AGG   ACC   CCT   GGA

      • AGG   ACA   UGA   GGA

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      2
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      A group of scientists were working on a project to sequence the DNA of an endangered species of gorilla in order to deduce the nucleotide base sequence of a specific gene of interest.

      What is the correct process that the scientists may have followed in order to sequence this specific gene from a sample of DNA extracted from a gorilla?

      A. HindIII is added to the sample to cut the DNA on either side of the gene of interest The double stranded fragments are separated into single strands Single stranded copies are made using fluorescently labelled nucleotide bases (A, T, C, G) Capillary electrophoresis is used to separate the DNA by size
      B. A restriction enzyme is added to the sample to cut the DNA on either side of the gene of interest  The double stranded fragments are copied using DNA polymerase Single stranded copies are made using fluorescently labelled nucleotide bases (A, T, C, G) Gel electrophoresis is used to separate the DNA by charge
      C. HindIII is added to the sample to cut the DNA on either side of the gene of interest The double stranded fragments are separated into single strands Single stranded copies are made using fluorescently labelled nucleotide bases (A, U, C, G) Capillary electrophoresis is used to separate the DNA by charge
      D.  A restriction enzyme is added to the sample to cut the DNA on either side of the gene of interest  Ligase enzyme is used to attach a promotor region to the start of the gene sequence Single stranded copies are made using fluorescently labelled nucleotide bases (A, U, C, G) Capillary electrophoresis is used to separate the DNA by size

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        3
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        The two karyotypes belong to a donkey (Q) and a horse (R).

        h-31

        Breeding these two individuals resulted in the production of a sterile mule (S).

        Why would S be sterile?

        • The sex of the mule (S) will be undetermined at birth due to the unnatural combination of chromosomes

        • Different combinations of alleles formed as a result of crossbreeding Q and R which leads to disadvantageous characteristics in S

        • There are different numbers of chromosomes in the gametes of Q and R so S would not live long enough to breed

        • The process of meiosis will not be possible in S as homologous pairs cannot form

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        4
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        Which of the following statements are true for the determination of sex?

        1. The chromosomes inherited through the maternal gametes determine the sex of the offspring
        2. Females have a larger quantity of DNA than males
        3. Sex is determined by the 23rd pair of chromosomes in humans
        4. Sex of an individual can be identified using an image taken of chromosomes during interphase

        • I and II only

        • III only

        • II and III only

        • I, III and IV only

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        5
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        Cytochrome C is a protein which is common to all organisms and is therefore a useful gene sequence to study when constructing phylogenetic trees to represent evolutionary relationships.

        The table shows the number of nucleotide differences in the cytochrome C genes of several different species.

        nucleotide-base-comparisons-mcq

        Which of the following shows the correct order of the organisms if arranged from the most closely related to the least closely related compared to humans?

          1. Human
          2. Chicken
          3. Fruit fly
          4. Yeast
          5. Mouse
          6. Rat
          1. Human
          2. Rat
          3. Mouse
          4. Fruit fly
          5. Yeast
          6. Chicken
          1. Human
          2. Mouse
          3. Rat
          4. Chicken
          5. Fruit fly
          6. Yeast
          1. Human
          2. Yeast
          3. Fruit fly
          4. Chicken
          5. Rat
          6. Mouse

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