Syllabus Edition

First teaching 2014

Last exams 2024

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Species, Communities, Ecosystems & Energy Flow (DP IB Biology: SL)

Exam Questions

3 hours36 questions
11 mark

Which is the correct definition for a species?

  • A group of organisms which look similar.

  • A group of organisms with similar characteristics.

  • A group of organisms which can interbreed to produce fertile offspring.

  • A group of living things.

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21 mark

Euglena is an autotroph.

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Identify, from the diagram, the feature which indicates this is an autotrophic organism.

  • Nucleolus

  • Chloroplast

  • Contractile vacuole

  • Mitochondria

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31 mark

Which option correctly lists some abiotic features of an ecosystem?

  • Mineral ions, light intensity, temperature

  • Competition, predation

  • pH, producers, mineral ions

  • Wind speed, decomposition, mineral ions

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41 mark

Identify the main energy transfers carried out by the organisms in the food web below:

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  Grass Rabbit
A light → chemical chemical → light
B chemical → light kinetic →  heat
C light → heat chemical → thermal
D light → chemical chemical → kinetic

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    51 mark

    A simple aquatic mesocosm is shown below

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    Why is A an important component of the mesocosm?

    • A provides protection for the primary consumers from predators.

    • A converts heat energy to chemical energy.

    • A provides carbohydrates and oxygen to support the mesocosm.

    • A helps to maintain a stable temperature.

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    11 mark

    In a woodland habitat, blue tits and other small birds feed on various species of caterpillar and beetle, which themselves feed on the leaves of trees and herbaceous plants. 

    Which of the following statements accurately describes a population within this example?

    • All of the organisms living in the habitat, together with their living and non-living interactions.

    • All of the small birds living in the habitat.

    • All of the blue tits living in the habitat.

    • All of the living organisms in the habitat.

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    21 mark

    Sea cucumbers are heterotrophic marine organisms that feed on dead or waste material from the seafloor and surrounding water.  They pick up and consume food particles using specialised tube feet that surround their mouths, as shown in the diagram below.

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    Which mode of nutrition and explanation is correct for sea cucumbers?

      Mode of nutrition Explanation
    A Detritivore They feed on dead and waste material and carry out external digestion
    B Detritivore They feed on dead and waste material and carry out internal digestion
    C Saprotroph They feed on dead and waste material and carry out internal digestion
    D Consumer They feed on living organisms

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      31 mark

      Which of the following statements about inorganic nutrients are correct? 

      1. Living organisms gain all of their inorganic nutrients from the abiotic environment.
      2. Inorganic nutrients include simple compounds of carbon, hydrogen, oxygen, and nitrogen.
      3. Organisms need inorganic nutrients to build organic molecules.
      • I and II only

      • I and III only

      • II and III only

      • I, II, and III

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      41 mark

      Why are ecosystems considered to be sustainable?

      • They do not require any outside input.

      • Nutrients such as nitrogen and carbon are constantly recycled.

      • Nutrients and energy are constantly recycled.

      • Nutrients are recycled and photosynthesis converts light energy into chemical energy.

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      51 mark

      Which of the following statements is an example of a theory being used to explain a natural phenomenon?

      • Energy loss at each trophic level causes the short length of food chains.

      • Trophic levels contain less biomass as you go higher up the food chain.

      • Energy is lost in the form of heat during the respiration reactions.

      • There is an association between the distributions of limpets and dog whelks within a rocky shore habitat.

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      61 mark

      The energy transferred from the sun to the grass in this food chain is 65 000 kJ m-2 year-1.

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       Approximately how much energy is passed from the shrew to the owl in kJ m-2 year-1?

      • 650 000

      • 6 500

      • 650

      • 65

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      71 mark

      Which of the following statements about quadrat sampling are true? 

      1. Sampling must be random to avoid bias.
      2. Random samples can be achieved by closing your eyes and throwing a quadrat.
      3. Quadrat sampling is only useful for small organisms.
      • I only

      • I and II only

      • I and III only

      • I, II, and III

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      81 mark

      A chi-squared test was carried out to test for association between species A and species B.  The results of the chi-squared test are given below. 

      Results of chi-squared test:

      Chi-squared value 5.89
      Degrees of freedom 1

      Critical values table:

      Degrees of freedom Probability level
      0.1 0.05 0.01 0.001
      1 2.71 3.84 6.64 10.83
      2 4.60 5.99 9.21 13.82

      What can be concluded from the chi-squared test for association carried out to test for association between species A and species B?

      • There is no significant association between species A and species B

      • Species A competes with species B for resources

      • There is a statistically significant association between species A and species B at the 5% probability level

      • There is a statistically significant association between species A and species B at the 1% probability level

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      91 mark

      Which of the following considerations should be taken into account when building a mesocosm to test the impact of a particular environmental variable?

      A Any type of container can be used No secondary consumers Inclusion of autotrophs Producers should be slow-growing
      B Transparent container Food chains of up to three organisms can be included Inclusion of autotrophs Producers should be slow-growing
      C Transparent container No secondary consumers Inclusion of autotrophs A control mesocosm should be built
      D Transparent container

      No secondary consumers

      Inclusion of autotrophs

       Soil should be sterilised to prevent contamination

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        101 mark

        Which pyramid of energy correctly represents the food chain shown?

        Algae → caddis fly larvae → small fish → kingfisher

        biology-q10-ib-hl-4-1

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          1
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          1 mark

          The Ghost Orchid (Epipogium aphyllum) is a rare plant species which lacks leaves or chlorophyll. The plant has formed a symbiotic relationship with a fungus in order to obtain the nutrition it requires. The growth of the fungus is slowed as a result of the relationship.

          Which of the following rows correctly describes E.aphyllum?

            Heterotroph Autotroph Parasite Saprotroph
          A ✓ X X ✓
          B X ✓ X ✓
          C ✓ X ✓ ✓
          D ✓ X ✓ X

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            2
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            1 mark

            Which of the following statements about inorganic nutrients are true?

            1. Carbon and hydrogen are key components of inorganic ions necessary for cell growth and development
            2. Inorganic ions enter the ecosystem through plant roots using energy from ATP
            3. Drought leading to dry soils results in a reduced availability of inorganic ions
            4. Sustainability of an ecosystems relies on inorganic ions being locked up within the biomass of an organism
            • I, II and IV

            • II and III

            • II, III and IV

            • II only

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            3
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            1 mark

            The graph shows changes in percentage cover of four plant species on a sand dune ecosystem over 500 years.

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            Which of the following explanations cannot be supported using the information in this graph.

            • All four species never formed part of the same community

            • Beech grass became extinct after 100 years

            • Interspecific competition between conifer trees and shrub bunchgrass occurs leading to a decrease in shrub bunchgrass

            • Intraspecific competition results in a decrease in conifer trees after around 400 years

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            4
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            1 mark

            A water quality investigation was carried out after some cases of heavy metal poisoning were detected in a countryside village with a river running through it. The investigators were trying to establish if poisoning was worse on the north or the south of the river.

              North of the river South of the river
            Number of cases of heavy metal poisoning 26 12

            The results from a chi-squared test were:

            Chi-squared value: 5.2
            Degrees of freedom: 1

            Critical values table:

            Degrees of Freedom P = 0.05 P = 0.01 P = 0.001
            1 3.83 6.64 10.83
            2 5.99 9.21 13.82
            3 7.82 11.35 16.27

            What conclusions can be drawn from the information above?

            • The χ2 value is greater than the critical value so there is an association between heavy metal poisoning and location

            • The  χ2 value is lower than the critical value so there is no association between heavy metal poisoning and location

            • Poisoning from heavy metals is worse in villages

            • Heavy metals are found in both locations, north and south of the river

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            5
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            1 mark

            Which row of the table correctly identifies an observation of food chains and the theory used to explain that observation?

              Observation Theory
            I Food chains are short Energy losses occur at each trophic level
            II Food chains have a pyramid structure Organisms with a larger biomass provide more energy to the next trophic level
            III Food chains all start with a producer Producers transfer energy most efficiently
            IV Energy losses occur at each trophic level Energy is transferred to the surroundings during respiration 
            • I only

            • I and IV

            • II and IV

            • I and III

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            6
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            1 mark

            Which of the following is not true about mesocosms?

            • Mesocosms allow the control of environmental conditions

            • Mesocosms allow collection of reliable data

            • Continuous data can be collected from a mesocosm

            • It is easy to mimic natural environmental conditions in a mesocosm

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