IB Biology SL D4.3 Climate change questions

Exam-style multiple choice and written questions with full markschemes. Check multiple choice answers straight away, or type, photograph or draw a written answer and get it marked.

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Question 1

Multiple choiceMedium1 mark

A shift in ocean currents leaves surface water in a coastal region warmer during the season when nutrients normally rise from deeper water. Which paired change is most likely?

Show answer and explanation

Answer: D. Warmer surface water can impede nutrient upwelling, so fewer nutrients reach the surface. The reduced nutrient supply lowers primary production, decreasing energy flow through marine food chains.

A: identifies the decline in nutrients and production but reverses the resulting change in energy flow. B: reverses the effect of reduced nutrient availability on primary production. C: reverses the effect of warmer surface water on nutrient upwelling, while keeping the later links consistent.

Remember: Lower primary production means less energy enters marine food chains.

Question 2

Paper 2Medium16 marks

Three temperate sites were managed using different approaches to restoration: planting non-native trees, allowing native forest to regenerate, or restoring a peat-forming wetland by re-establishing waterlogged conditions. Waterlogging at the wetland limits the decomposition of dead plant material.

Each approach was studied at one site. Three plots were sampled at each site. Figure 1 shows the mean net increase in carbon stored in vegetation and soil relative to the start of restoration. Table 1 shows the mean number of native plant species recorded per 20 quadrats after 15 years, averaged across the three plots.

Table 1

Restoration approach	Mean number of native plant species per 20 quadrats after 15 years
Non-native tree plantation	7
Native forest regeneration	19
Restored peat-forming wetland	15

(a)

Identify the restoration approach with the greatest increase in carbon stored after 10 years.

[1]

(b)

Calculate the mean annual increase in carbon stored in the restored peat-forming wetland between years 5 and 15. Give your answer with a unit.

[2]

(c)

Describe and compare the changes in carbon stored in the three restoration approaches over the 15-year period.

[3]

(d)

Explain how tree-based restoration and restoration of a peat-forming wetland can each increase carbon storage.

[4]

(e)

A project manager argues that non-native tree plantations should be chosen as the best option, considering carbon storage and native plant diversity over the first 15 years. Evaluate this claim using Figure 1 and Table 1.

[4]

(f)

Suggest one limitation of the investigation’s design and explain how it could affect the comparison of restoration approaches.

[2]

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