IBBiology: HLDPExam Questions9. Plant Biology (HL Only)9.3 Growth in Plants

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First teaching 2014

Last exams 2024

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Growth in Plants (DP IB Biology: HL)

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9.3 Growth in Plants

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9.3 Growth in Plants

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1
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Which row of the table correctly identifies the parts labelled J, K, L and M on the diagram below?9-3_q1e

  J K L M
A. axillary bud shoot apical meristem root apical meristem lateral meristem
B. shoot apical meristem axillary bud lateral meristem root apical meristem
C. lateral meristem shoot apical meristem root apical meristem axillary bud
D. shoot apical meristem lateral meristem axillary bud root apical meristem

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    2
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    The image below shows an example of topiary, an art form in which gardeners trim species of plants such as privet (Ligustrum ovalifolium) to form decorative shapes in gardens. The gardener is shown here on a ladder, trimming the upper parts of the topiary shape.

    9-3_q2e

    What phenomenon of plant growth allows such forms to be shaped in plants?

    • Negative geotropism

    • Cell differentiation in the shoot apex

    • Apical dominance

    • Production of the plant hormone indole-3-acetic acid (IAA)

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    3
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    A sycamore tree seed lands on sloping ground at a particular spot, shown as X in the diagrams. Conditions there are favourable to the sycamore seed's germination. 

    Which diagram of A - D best shows the direction of growth of the tree's shoots and roots in its early life after germination of the seed?

    • 9-3_q3ea

    • 9-3_q3eb

    • 9-3_q3ec

    • 9-3_q33d

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    4
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    Which row of the table gives the most accurate summary of the actions of auxins?

      In shoots In roots
    A. Cells elongate Growth inhibited
    B. Cells grow in number Growth inhibited
    C. Cells elongate Growth promoted
    D. Cells grow in number Growth promoted

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      5
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      Which of the following statements are true for the activity of micropropagation of plants?

      1. Explants are sterilised to reduce the risk of microbial contamination of the culture medium
      2. Micropropagation produces a desirably high amount of variation within the culture
      3. Explants can give rise to whole new plants thanks to totipotent cells in their meristems
      4. Plant hormones are not used in micropropagation until the new plants are full-sized
      5. New plants are able to grow in soil once their roots and shoots have developed, after micropropagation

      • II, III and IV

      • I and III only

      • I, III and V

      • All of them

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      11 mark

      A gardener accidentally cut off the apical meristem while pruning a shrub in her garden. After a few weeks she noticed some changes in the growth of the shrub.

      Which of the following would most accurately describe these changes?

      • The shrub would grow much taller and the axillary buds would be inhibited

      • The main stem of the shrub would greatly increase in diameter

      • The axillary buds will develop and lead to greater branching in the shrub

      • The axillary buds will be inhibited leading to less branching in the shrub

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      21 mark

      Which of the following meristems is correctly matched with the tissue that it can form?

       

      Meristem

      Tissue
      A

      Ground tissue

      Parenchyma forming the pith
      B

      Protoderm

      Collenchyma forming supportive tissue
      C

      Procambium

      Epidermis
      D

      Protoderm

      Xylem and Phloem

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        31 mark

        A pot plant falls over and after a few days shows the following growth pattern.q3_9-3_growth_in_plants_ib_biology_hl_mcq

        Which of the following is the most accurate explanation for the growth shown at each of the labels on the diagram?

        • This part of the stem demonstrates negative gravitropism in order to receive the maximum amount of sunlight for photosynthesis

        • This part of the stem shows positive phototropism as it will bend towards the light

        • The lateral roots demonstrates negative gravitropism as they are not growing towards gravity

        • The main root shows positive gravitropism as it is bending towards gravity

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        41 mark

        What would not be considered a function of auxins?

        • Stimulates cell elongation in shoots, leading to an increase in plant height

        • Stimulates the development of axillary buds further away from the shoot apical meristem

        • Inhibits the development of axillary buds close to the shoot apical meristem

        • Inhibits cell elongation in root cells, therefore slowing down root growth

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        51 mark

        The following steps describe the possible pathway of gene expression affecting the transport of auxin in a plant.

        1. This affects the expression of certain genes coding for PIN3 proteins
        2. There is a change in their 3D shape
        3. Light energy is absorbed by phototropins
        4. Phototropins bind to receptors inside the cell

        Which of the following represents the correct order of these steps?

        • IV → I → II → III

        • III → II → IV → I

        • IV → II → III → I

        • III → IV → II → I

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        61 mark

        Which would be the most accurate description and explanation for the growth response that would be observed in the shoot tip below?q6_9-3_growth_in_plants_ib_biology_hl_mcq

         

        Description

        Explanation
        A

        The shoot tip grows away from the light source

        Auxins inhibit cell elongation on the shady side of the shoot tip
        B

        The shoot tip grows towards the light source

        Auxins inhibit cell elongation on the side of the light source
        C

        The shoot tip continues to grow straight up

        Auxins are evenly distributed across the shoot tip
        D

        The shoot tip grows towards the light source

        Auxins cause cell elongation on the shady side of the shoot tip

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          71 mark

          Which of the following would explain the reason why a root turned on its side shows positive gravitropism?

          1. Statoliths will accumulate on the lower side of cells due to gravity
          2. PIN3 transporter proteins will distribute to the upper side of the root
          3. High concentration of auxin on the upper side of the root will inhibit cell elongation
          4. Cells elongate at a higher rate at the lower side of the root

          • I only

          • I and II only

          • I, III and IV

          • II, III and IV

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          81 mark

          Microarrays have provided more advanced opportunities for scientists to understand plant growth responses.

          What has been the greatest advantage of using microarrays in this field of study?

          • It provides a visible way to determine the concentration of plant growth substances in certain cells

          • Predictions can be made regarding the expression of certain genes in different plant species

          • It provides a visible way to determine the level of gene expression in certain cells

          • The distribution of plant growth substance levels can be determined in different parts of the plant

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          91 mark

          The following diagram shows part of the process of micropropagation.q9_9-3_growth_in_plants_ib_biology_hl_mcq

          What property of the growth medium correctly describes how the explants will develop?

           

          Auxin : Cytokinin

          Description of plant development
          A

          Greater than 10 : 1

          The explant will develop shoots and begin to photosynthesise
          B

          1 : 1

          Development of both roots and shoots will take place
          C

          Less than 10 : 1

          The explant will develop roots and can be planted in soil
          D

          1 : 1

          Develop into an undifferentiated group of cells called a callus

           

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            101 mark

            Which of the following would not be considered an application of micropropagation?

            • Producing many copies of new varieties of endangered plant species to allow for replanting in the wild

            • Producing strains of existing plant varieties that are free from viral, fungal and bacterial infections

            • Creating new varieties of endangered plant species to allow for replanting in the wild

            • Preserving favourable characteristics in commercially valuable plant species

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            1
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            Meristem cells at the tip of a growing shoot differentiate into specialised cells as the shoot grows, forming stems and other differentiated plant tissues e.g. ground tissues.

            Which of A - D best explains why there is always a number of meristem cells in a shoot apex even as the shoot grows?

            • The coleoptile (early shoot) contains enough meristem cells to provide for a juvenile plant to grow into a fully-grown plant.

            • Mitosis in the shoot tip results in 2 daughter cells, one of which remains meristematic while the other cell differentiates.

            • Mitosis in the shoot tip results in 4 daughter cells, two of which remain meristematic while the other two differentiate.

            • The action of plant hormones reverses the effects of differentiation on certain cells, turning them back into meristem cells.

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            2
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            The image below shows two tree species native to North America.

            The Jeffrey pine (Pinus jeffreyi) typically grows to 45m height at maturity, whereas the silver maple (Acer saccharinum) would only grow to 25m. 9-3_q2h

            Which table would be the best choice for predicting the levels of indole-3-acetic acid (IAA) at two parts of a typical growing shoot of these two trees?

            •  

              Jeffrey pine

              Silver maple
              At shoot apex High High
              At first axillary bud Low High
            •  

              Jeffrey pine

              Silver maple
              At shoot apex High Low
              At first axillary bud High Low
            •  

              Jeffrey pine

              Silver maple
              At shoot apex Low High
              At first axillary bud High Low
            •  

              Jeffrey pine

              Silver maple
              At shoot apex High Low
              At first axillary bud High High

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            3
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            Which of A - D gives the most accurate description of how efflux pumps contribute to plant tropisms?

            • Efflux pumps pump low-density particles to the top of a horizontal root in order to initiate a positive gravitropism. 

            • Light denatures PIN3 proteins which leads to fewer efflux pumps, and hence less cell elongation, on the sunny side of a plant shoot. 

            • Efflux pumps are coded for by PIN3 genes and carry auxins from one cell to another in order to maintain an uneven distribution of auxins.

            • Efflux pumps carry auxins away from growing tissues on the removal of a stimulus, in order to maintain an even distribution of auxins.

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            4
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            Which of the following statements apply to the use of microarrays in the study of plant growth?

            1. A microarray is used to ascertain whether a gene is being expressed or not.
            2. RNA in the tissue sample binds to short DNA probes by covalent bonding.
            3. The DNA probes carry a radioactive marker and can be visualised when they bind to a piece of transcribed RNA.
            4. Microarrays can reveal phenotypic traits that are not necessarily easily observable in an experiment.
            5. Microarrays will only display if a gene is being transcribed at the exact time of analysis.

            • I, IV and V

            • III, IV and V

            • All of them

            • I, III, IV and V

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            5
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            The plant tissue cambium gets its name from the word cambio, which in Spanish means 'change'.

            Which of A - D gives the best explanation for cambium tissue having this name?

            • Cambium can change its function from day to day depending on the requirements of the plant. 

            • The direction of flow in cambium vessels can change according to the needs of the plant at a particular time of day, or with weather fluctuations. 

            • Cambium can change, by differentiation, into xylem or phloem tissues as the plant grows.

            • Cambium has the ability to change the tropism responses of a plant's shoots and roots in response to external stimuli. 

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