Climate changeIB MYP Biology: Subtopic test

1. 1
   Scientists estimate that the Earth's average surface temperature is about 15 °C. Without any greenhouse gases in the atmosphere, it would be about -18 °C, and most life on Earth could not survive.

   (a)

   Which two gases in the atmosphere are greenhouse gases?

   [1 mark]

   • ACarbon dioxide and methane
   • BOxygen and nitrogen
   • CArgon and hydrogen
   • DHelium and neon

   (b)

   What do greenhouse gases do that keeps the Earth warm?

   [1 mark]

   • AThey reflect all sunlight back into space
   • BThey absorb infrared radiation from the Earth and re-emit some of it back towards the surface
   • CThey burn in the atmosphere to release heat
   • DThey block all radiation from the Sun

   (c)

   Explain how the greenhouse effect keeps the Earth's surface warm.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A country in South America has increased its beef farming and cleared large areas of rainforest for new pasture. It also generates most of its electricity from power stations that burn coal and gas, and its vehicles burn petrol and diesel.

   (a)

   Which activity in the country releases methane?

   [1 mark]

   • AUsing solar panels
   • BPlanting forests
   • CKeeping large herds of cattle
   • DRecycling glass

   (b)

   How does clearing the rainforest increase the carbon dioxide in the atmosphere?

   [1 mark]

   • ATrees release carbon dioxide during photosynthesis
   • BCleared soil releases oxygen
   • CTrees use up methane in the air
   • DFewer trees absorb carbon dioxide, and burning or rotting trees release it

   (c)

   Explain why burning coal and petrol increases the amount of carbon dioxide in the atmosphere.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   Atmospheric carbon dioxide measurements show a concentration of about 280 parts per million (ppm) in 1800 and about 420 ppm in 2023. Over a similar period, the average global surface temperature has risen by about 1.1 °C.

   (a)

   Describe the change in atmospheric carbon dioxide concentration between 1800 and 2023 and calculate the percentage increase.

   [3 marks]

   (b)

   Explain how the increase in carbon dioxide leads to a rise in global temperature, and describe one effect of this rise.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   Students at a school in Johannesburg want to model the greenhouse effect. The government of their country, which generates most of its electricity in coal-fired power stations, is deciding whether to replace them with wind and solar farms.

   (a)

   Outline an investigation the students could carry out to test whether a higher carbon dioxide concentration makes air warmer when it is heated by a lamp.

   [6 marks]

   (b)

   Evaluate the government's idea of replacing coal-fired power stations with wind and solar farms.

   [6 marks]

   Total for question 4: 12 marks

End of questions