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Chapter 3 Practice Paper: Organisms and their Environment — question paper

QuizQuipPractice Series
QQ/S4CBI/CH3

Secondary 4 · Combined Science (Biology) (G2 / G3)

Chapter 3 Practice Paper

Organisms and their Environment

Duration: 40 minutes
Total: 30 marks
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READ THESE INSTRUCTIONS FIRST

  • Answer all questions.
  • Section A: choose the one correct answer for each multiple-choice question.
  • Section B: answer in the spaces provided; show all necessary working.
  • Give numerical answers to 3 significant figures where appropriate, with units.
  • Biological drawings are not required; describe or label structures in words where asked.
  • The use of a calculator is permitted.

Original practice material written for the MOE Combined Science (Biology) syllabus. It is not an official MOE or school examination paper. Chapter 3 (energy flow; producers, consumers, decomposers; energy losses; pyramids of numbers and biomass; carbon cycle and sinks; global warming).

For Examiner’s Use
Section A/ 10
Section B/ 20
Total/ 30

Section A: Multiple-choice questions[10 marks]

Choose the one correct answer for each question.

  1. 1

    In the chain grass → zebra → lion, the zebra is a

    1. Aproducer
    2. Bprimary consumer
    3. Csecondary consumer
    4. Ddecomposer
    ( )
  2. 2

    Energy enters an ecosystem as

    1. Aheat from respiration
    2. Bwaste from decomposers
    3. Csunlight captured by producers
    4. Dcarbon dioxide
    ( )
  3. 3

    Why are top predators always rare in an ecosystem?

    1. Athey are hunted by decomposers
    2. Bso little energy survives to their level
    3. Cthey photosynthesise poorly
    4. Dthey need no food
    ( )
  4. 4

    A numbers pyramid is inverted at the base when

    1. Aone large producer supports many small consumers
    2. Bthe sun is included
    3. Cdecomposers outnumber producers
    4. Dall consumers are huge
    ( )
  5. 5

    Which pair of processes returns carbon dioxide to the atmosphere?

    1. Aphotosynthesis and feeding
    2. Bcondensation and decay
    3. Cphotosynthesis and dissolution
    4. Drespiration and combustion
    ( )

Section B: Structured questions[20 marks]

Answer all questions in the spaces provided.

  1. 1

    A meadow food web includes grass, grasshoppers, frogs, snakes and mushrooms on dead logs.

    1. (a)

      Assign each organism to its role: producer, consumer (state level) or decomposer.

      [4]
    2. (b)

      State the direction food-chain arrows are drawn and why.

      [1]
    3. (c)

      State one advantage of the meadow)s feeding relationships forming a web rather than single chains.

      [2]
  2. 2

    The energy in the producers of a habitat is 50 000 kJ.

    1. (a)

      Assuming 10% transfer between levels, calculate the energy in the primary and secondary consumers.

      [2]
    2. (b)

      Explain why the energy passed on is only about 10%.

      [3]
    3. (c)

      State why energy flow is described as non-cyclical, unlike the carbon cycle.

      [2]
  3. 3

    A tropical country clears rainforest for oil-palm plantations and burns the felled trees.

    1. (a)

      State two reasons the clearing raises atmospheric carbon dioxide.

      [2]
    2. (b)

      Explain the term carbon sink and state one example from the oceans.

      [2]
    3. (c)

      Suggest two actions the country could take to reduce its carbon dioxide output.

      [2]

— End of paper —