IB Biology SL D4.3 Climate Change Questions

Practise IB Biology SL D4.3 by linking greenhouse gases to warming, feedback loops and biological impacts across ecosystems.

Exam points

Explain how fossil fuels, cement, deforestation and livestock add greenhouse gases and intensify warming.
Explain ice-albedo and permafrost greenhouse-gas positive feedback that amplifies warming.
Explain how warming, drought, fire, pests and competition can drive boreal-forest decline and habitat loss.
Explain how polar ice loss changes habitat, migration, competition, food webs and species survival.
Interpret climate-induced range shifts and their effects on competition, predation, prey availability and survival.
Explain coral bleaching, acidification, reduced calcification and their consequences for reef biodiversity.
Identify how deforestation, afforestation and peatland conditions change carbon sequestration and storage.

Covered syllabus points

D4.3.1—Anthropogenic causes D4.3.2—Positive feedback cycles D4.3.3—Boreal forest tipping point D4.3.4—Polar habitat changes D4.3.5—Ocean current changes D4.3.6—Range shifts D4.3.7—Coral reef threats D4.3.8—Carbon sequestration approaches

[Maximum number: 7]

Carbon is an essential element for life on Earth and must be distributed and recycled within ecosystems.

Explain the impact of anthropogenic activity on climate change.

a. greenhouse effect describes that greenhouse gases trap long-wave radiation from the Earth's surface and absorbs it keeping the Earth warm

OR

increase in greenhouse gases trapped in atmosphere increases Earth's temperature;

b. burning of fossil fuels/peat/coal/natural gas by humans has released more $\mathrm{CO}_{2}$ into the atmosphere causing temperature rise on Earth;

c. raising livestock for feed has added methane/greenhouse gas to the atmosphere causing more heat to be trapped on Earth;

d. industrial processes / fertilizer production has increased the concentration of nitrous oxides/greenhouse gases in the atmosphere;

e. deforestation has increased the amount of $\mathrm{CO}_{2}$ in the atmosphere/reduced an important sink for $\mathrm{CO}_{2}$ ;

f. increased temperatures have caused melting of land ice leading to changes to polar habitats/decreasing species ability to survive

OR

melting of ice/snow causes reduction in albedo, so there is more insolation absorbed at Earth's surface;

g. warmer surface water prevents upwelling of nutrients/decreases ocean productivity;

h. coral reef habitat destruction due to changes in water pH / temperature;

i. warmer temperatures/decreased snowfall has led to droughts and loss of life/habitats;

j. rates of decomposition of peat/organic matter increases greenhouse gases;

k. ocean/sea level rise from melting ice/thermal expansion of oceans has impacted coastal regions/loss of land;

I. changing weather patterns due to global warming has caused loss of life and infrastructure;

m. poleward migrations/migrations to more suitable places due to climate changes at lower latitudes;

[Maximum number: 1]

Which of the following may contribute to a positive feedback cycle in global warming?

The release of methane from thawing ice caps

The uptake of carbon dioxide by a reforested area

Higher temperatures increasing photosynthesis rates

The accumulation of peat in swamps

[Maximum number: 4]

Boreal forests stretch across Canada, Russia and Scandinavia. This northern ecosystem accounts for 29 % of the world's forest areas. The long, cold winters favour tall evergreen trees with either needles or scale-like leaves. These trees are wind-pollinated and their seeds are not enclosed in a fruit. The photograph shows a typical boreal forest in winter.

Boreal forest in winter, with a dense stand of tall pointed trees covered in snow beside an open snow-covered foreground.

(a)

In some areas there are gaps in the boreal forest where trees fail to grow and peat tends to accumulate. Suggest reasons for this.

[ 2 ]

(b)

An increase in global temperatures poses a critical threat to boreal forests. Explain the consequences of climate change to this northern ecosystem.

[ 2 ]

[Maximum number: 2]

An increase in global temperatures poses a critical threat to boreal forests. Explain the consequences of climate change to this northern ecosystem.

[Maximum number: 6]

Aquatic and other environments are being affected by a global rise in temperature. Outline the consequences of this on arctic ecosystems.

[Maximum number: 2]

Bottlenose dolphins (Tursiops truncatus) inhabit almost all tropical and temperate oceans between $45^{\circ} \mathrm{N}$ and $45^{\circ} \mathrm{S}$ . Over a two-year period, aerial surveys were carried out to investigate the seasonal distribution of these animals along the mid-Atlantic and eastern coastal waters of the USA. Sightings were recorded using a global positioning system (GPS) while flying parallel to the coast approximately 500 m offshore. The diagram below shows a map of the section of coast surveyed. The bar graph shows the seasonal data for summer and winter at the corresponding latitudes ( ${ }^{\circ} \mathrm{N}$ ). A total of 5431 bottlenose dolphins were sighted during these surveys.

Explain how an increase in water temperature due to global warming could affect the distribution of bottlenose dolphins along the eastern coast of the USA.

[Maximum number: 2]

High-temperature tolerance experiments were performed on Pocillopora damicornis, a coral in the tropical eastern Pacific, in the Gulf of Panama. The scattergraph shows the zooxanthellae densities at three temperature treatments over a 10-week period.

Using the data, explain the effect of temperature on coral bleaching in the Gulf of Panama.

a. bleaching is zooxanthellae expulsion from coral;

b. high temperature/ $30^{\circ} \mathrm{C} / 32^{\circ} \mathrm{C}$ resulted in loss/death of zooxanthellae (causing bleaching)

OR

negative correlation between temperature and zooxanthellae density OR

positive correlation between temperature and bleaching;

c. photosynthesis in zooxanthellae disrupted which leads to expulsion of zooxanthellae

OR

production of toxic substances which leads to expulsion of zooxanthellae;

[Maximum number: 1]

Which action will decrease carbon sequestration?

Afforestation

Primary production

Deforestation

Rewetting peatlands

All question bank results loaded

a	waterlogged soil/poor drainage OR acidic soil OR anaerobic conditions/soil;
b	organic matter is not fully decomposed leading to peat formation OR decomposers/saprotrophs less active/fewer in cold temperatures;

Covered syllabus points

Question 1

Question 2

Question 3

Question (a)

Question (b)

Question 4

Question 5

Question 6

Question 7

Question 8