9477 / 2027

Climate, biodiversity and disease ecology

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Which most directly adds geological carbon to the active atmosphere?

  1. Respiration of recently grown crop biomass
  2. Burning fossil fuel
  3. A leaf temporarily storing newly absorbed CO2
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Burning fossil fuel

Carbon stored over geological times is released as CO2.

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Which makes an energy comparison fairest?

  1. Ignore construction for one source but include it for another.
  2. Compare total emissions of different-sized plants without their outputs.
  3. Compare life-cycle emissions per unit electricity with consistent boundaries.
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Compare life-cycle emissions per unit electricity with consistent boundaries.

The common service and boundary support a meaningful comparison.

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Which is a climate positive feedback?

  1. Extra plant carbon uptake lowers atmospheric CO2.
  2. A warmer surface emits more thermal radiation to space.
  3. Thaw permits decomposition that releases more greenhouse gases.
  4. More dissolved carbon dioxide raises ocean pH and speeds coral calcification.
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Thaw permits decomposition that releases more greenhouse gases.

Additional greenhouse gases can reinforce the warming that caused thaw.

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Which is primarily a physical coastal-protection mechanism?

  1. Photosynthesis incorporating CO2 into tree biomass, which slows climate change
  2. Low oxygen slowing decomposition in sediment
  3. Roots and stems dissipating wave energy and trapping sediment
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Roots and stems dissipating wave energy and trapping sediment

This changes water flow and shore stability.

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Which explains how flooding can reduce crop growth?

  1. It necessarily gives every root unlimited oxygen.
  2. It can reduce root oxygen supply and disrupt respiration.
  3. Waterlogged soil speeds up oxygen diffusion to the roots, so they respire too fast.
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It can reduce root oxygen supply and disrupt respiration.

Root metabolism can be limited despite abundant water.

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Which Aedes stages are aquatic in the normal life cycle?

  1. Larva and adult
  2. Egg and adult, but not pupa
  3. Larva and pupa
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Larva and pupa

These immature stages develop in water before adult emergence.

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Invented data: Aedes larvae took 14 days to reach adulthood at 20 degrees C, 9 days at 26 degrees C and 7 days at 32 degrees C, but survival was 80%, 75% and 20%. Which conclusion is best supported?

  1. Temperature has no effect on mosquitoes.
  2. More adults are produced at 32 degrees C.
  3. Warmer water speeds development but can lower survival.
  4. Survival rises as development speeds up.
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Warmer water speeds development but can lower survival.

Development time fell from 14 to 7 days, yet survival fell sharply to 20% at 32 degrees C.

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Which observation most directly indicates local transmission rather than importation alone?

  1. A traveller arrives with an infection acquired elsewhere
  2. Locally acquired infections linked to local vector exposure
  3. A temperature record rises by itself
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Locally acquired infections linked to local vector exposure

This supports a transmission chain within the setting.

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Question 1 of 9

Compare an energy claim

4 marks

A claim calls bioethanol zero-carbon and hydropower emission-free. Evaluate both using life-cycle reasoning and name a fair comparison unit. [4]

Include land use, production and site effects.

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