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Unit notes and practice questions

Grade 12 Biology unit 6: Climate Change

Everything here is for unit 6 of the Grade 12 Biology textbook: what the chapter covers, the short notes, practice questions with their answers, and the lesson video where one exists.

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Cards
10
Practice questions on unit 6
333–354
The textbook pages for unit 6

What unit 6 covers

  1. 1.Climate change: causes and effects
  2. 2.Effects of climate change
  3. 3.International conventions

Short notes for unit 6

The cards filed under this chapter on the Grade 12 Biology page. Open one at a time.

Greenhouse gasMajor sources
Carbon dioxide (CO2)Fossil fuel combustion, deforestation
Methane (CH4)Landfills, rice paddies, digestion in cattle and sheep
Nitrous oxide (N2O)Fertilizer, animal waste
Hydrofluorocarbons (HFCs)Semiconductor manufacturing and other industrial processes
Perfluorocarbons (PFCs)The same industrial processes, plus aluminium smelting
Sulfur hexafluoride (SF6)Electrical transmission systems, magnesium and aluminium production

When you use it

Use it to name the greenhouse gases and where each one mainly comes from when a question asks about the causes of global warming.

Watch out

Water vapour is the most plentiful greenhouse gas, but the exam asks about the ones people add. Carbon dioxide causes the largest share of the warming because so much of it is released.

Drafted from Grade 12 Biology, pages 333-354, then checked twice before it went up

When you use it

Use it when a question asks whether a change in the climate comes from natural cycles or from human activity.

Watch out

The mistake is to call every change natural. The earth does vary on its own, but since the Industrial Revolution people have added so much greenhouse gas that the warming now runs outside that natural range (anthropogenic means caused by people).

Drafted from Grade 12 Biology, pages 333-354, then checked twice before it went up

Practice questions on unit 6

10 multiple-choice questions written against this chapter, each with its answer and the reason. Try one before you open the answer.

Question 1

According to the chapter, what is climate change?

  1. A.A long-term change in the usual climate of the planet, such as temperature, precipitation and wind, especially caused by human activities
  2. B.A change in the weather that happens for one day only
  3. C.A change caused only by volcanic eruptions
  4. D.A change in the height of ocean tides
Show the answer and why

Answer: A A long-term change in the usual climate of the planet, such as temperature, precipitation and wind, especially caused by human activities

Why

The chapter defines climate change as a global change in the usual climate (temperature, precipitation and wind), especially caused by human activities, over multiple decades or longer. Weather for one day is not climate change, and volcanoes are not the main cause.

Question 2

Which of these is not listed in the chapter as one of the major greenhouse gases?

  1. A.Water vapour
  2. B.Carbon dioxide (CO<sub>2</sub>)
  3. C.Methane
  4. D.Oxygen
Show the answer and why

Answer: D Oxygen

Why

The chapter lists water vapour, carbon dioxide, methane and nitrous oxide as the major greenhouse gases. The chapter says oxygen and nitrogen do not absorb and radiate heat the way greenhouse gases do.

Question 3

The chapter says the average temperature of the earth is kept at 14°C by the greenhouse effect. Without the greenhouse effect, what would the temperature drop to?

  1. A.14°C
  2. B.40°C
  3. C.-18°C
  4. D.0°C
Show the answer and why

Answer: C -18°C

Why

The chapter states that without the greenhouse effect, temperatures would drop to as low as -18°C, which is too cold to sustain life on earth.

Question 4

Which human activity increases the concentration of atmospheric CO2, according to the chapter?

  1. A.Planting new forests
  2. B.Burning fossil fuels such as coal, oil and gas
  3. C.Rainfall
  4. D.Strong winds
Show the answer and why

Answer: B Burning fossil fuels such as coal, oil and gas

Why

The chapter says humans increase atmospheric CO2 by burning fossil fuels, cutting down forests and farming livestock. Among the choices, only burning fossil fuels is one of these named activities. Rainfall and winds are natural processes, not human causes.

Question 5

According to the chapter, increases in atmospheric CO2 are responsible for about what share of the total energy imbalance that is causing the earth's temperature to rise?

  1. A.One-third
  2. B.About two-thirds
  3. C.All of it
  4. D.One-tenth
Show the answer and why

Answer: B About two-thirds

Why

The chapter says increases in atmospheric carbon dioxide are responsible for about two-thirds of the total energy imbalance that is causing the earth's temperature to rise.

Question 6

In which year was Ethiopia's Green Legacy Initiative launched?

  1. A.2007
  2. B.2011
  3. C.2019
  4. D.2010
Show the answer and why

Answer: C 2019

Why

The chapter says the Green Legacy Initiative (GLI) was launched in 2019. The 2007 plan was the National Adaptation Plan of Action, and the CRGE strategy came in 2011.

Question 7

In which year was the Kyoto Protocol adopted?

  1. A.1992
  2. B.2009
  3. C.1997
  4. D.1994
Show the answer and why

Answer: C 1997

Why

The chapter states that the Kyoto Protocol was adopted on 11 December 1997. The UNFCCC was agreed in 1992, and the Copenhagen meeting (COP15) was in 2009.

Question 8

A cyclone moves at 62 km per hour near a coastal town. How far does it travel in 3 hours? Use the speed from the chapter.

  1. A.124 km
  2. B.60 km
  3. C.206 km
  4. D.186 km
Show the answer and why

Answer: D 186 km

Why

The chapter says cyclones move at sixty-two km per hour or more. Distance = speed × time, so 62 × 3 = 186 km. The other choices come from wrong multiplication or from using the wrong number.

Question 9

A fisherman at a coastal village in Ethiopia notices that the sea has suddenly pulled far back from the shore. What should he do first, according to the chapter's tsunami advice?

  1. A.Walk out onto the exposed sea floor to look at the fish
  2. B.Move inland to higher ground immediately
  3. C.Wait on the beach until the water comes back
  4. D.Stay near the shore and take photos
Show the answer and why

Answer: B Move inland to higher ground immediately

Why

The chapter says a noticeable recession in water away from the shore is nature's tsunami warning and should be heeded. The correct action is to move inland to higher ground immediately and stay there.

Question 10

According to the chapter, what causes most earthquake-related deaths and injuries?

  1. A.Being in open ground during the shaking
  2. B.Ground movement during the earthquake itself
  3. C.Collapsing walls, flying glass and falling objects
  4. D.Tsunami waves that follow every earthquake
Show the answer and why

Answer: C Collapsing walls, flying glass and falling objects

Why

The chapter says ground movement is seldom the direct cause of death or injury. Most earthquake-related casualties result from collapsing walls, flying glass and falling objects. This is why people are told to stay away from glass and to take cover.

The app holds 12 questions on this unit, marked as you go. These are the first 10.

Lesson video for unit 6

A lesson on this chapter from YouTube. It loads only when you press play.

Greenhouse effect and greenhouse gases · Watch on YouTube

The textbook pages for unit 6

Unit 6 runs from page 333 to page 354 of the Ministry of Education edition.

Ministry of Education edition, English, 358 pages

Download the PDF

All Grade 12 Biology short notes

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