Topic 16 Practice Paper: Organisms and their environment — question paper

Section A: Multiple-choice questions[10 marks]

Choose one answer for each question. Each question is worth 1 mark.

1. 1

   Energy enters living systems mainly as

   1. Aheat from the soil
   2. Blight from the Sun
   3. Cchemical energy from fossils
   4. Dsound from weather
   ( )
2. 2

   Which organism gets its energy from dead or waste organic material?

   1. AProducer
   2. BPrimary consumer
   3. CHerbivore
   4. DDecomposer
   ( )
3. 3

   The arrow in a food chain represents

   1. Athe direction animals face
   2. Bwater movement
   3. Cthe flow of energy to the eater
   4. Dfamily relationships
   ( )
4. 4

   The main advantage of a pyramid of biomass over a pyramid of numbers is that biomass

   1. Ais quicker to measure
   2. Bis always pyramid-shaped in numbers too
   3. Ccounts individuals more accurately
   4. Davoids distortion when organisms differ greatly in size
   ( )
5. 5

   Energy is transferred to the environment between trophic levels mainly through

   1. Aegestion, excretion and respiration
   2. Bphotosynthesis
   3. Cgermination
   4. Dtranspiration
   ( )
6. 6

   In the carbon cycle, combustion returns carbon to the atmosphere as

   1. Acarbon monoxide in soil
   2. Bcarbon dioxide
   3. Cmethane only
   4. Dsolid carbon
   ( )
7. 7

   Nitrogen-fixing bacteria convert

   1. Anitrates to nitrogen gas
   2. Bprotein to urea
   3. Cnitrogen gas into usable nitrogen compounds
   4. Dammonium to nitrate
   ( )
8. 8

   The phase of the sigmoid curve in which births equal deaths is the

   1. Alag phase
   2. Blog phase
   3. Cdeath phase
   4. Dstationary phase
   ( )
9. 9

   Herbicides increase crop yield by

   1. Areducing competition from weeds
   2. Bkilling pests that eat leaves
   3. Cadding minerals to soil
   4. Dbreeding better plants
   ( )
10. 10

    Which conservation measure protects young fish so they can grow and breed?

    1. ASmaller quotas for tourists
    2. BLarger mesh sizes in nets
    3. CRemoving all predators
    4. DFeeding fish fertiliser
    ( )

Section B: Structured questions[20 marks]

Answer all questions in the spaces provided.

1. 11

   The diagram shows a food web in a woodland. Trees are eaten by caterpillars and by deer; caterpillars are eaten by birds; birds are eaten by hawks; deer are also eaten by hawks.

   1. (a)

      State the trophic level of the birds.

      [1]
   2. (b)

      Describe the effect on the bird and hawk populations if caterpillars are wiped out by pesticide.

      [2]
   3. (c)

      Deer have no natural predators in this web except hawks. Explain what would happen to the tree population if all hawks were removed.

      [3]
2. 12

   Energy and nutrients move differently through ecosystems. (Extended)

   1. (a)

      Name the original energy source for almost all ecosystems.

      [1]
   2. (b)

      Explain why food chains rarely have more than five trophic levels.

      [3]
   3. (c)

      Describe the role of each of the following in the nitrogen cycle: nitrifying bacteria, denitrifying bacteria. (Extended)

      [3]
3. 13

   A valley is cleared of its forest to create pasture for cattle. Years later, a fertiliser store leaks into the stream feeding the valley’s lake. (Extended)

   1. (a)

      State three undesirable effects of clearing the forest.

      [3]
   2. (b)

      Explain how the fertiliser leak could reduce the oxygen content of the lake.

      [4]