D4.3 Climate change
Practice exam-style IB Biology questions for Climate change, aligned with the syllabus and grouped by topic.
Question 1
What is the main risk to emperor penguin breeding colonies from early breakout of Antarctic landfast ice?
A.
Carbonate ions become unavailable for eggshell formation.
B.
Eggs or chicks may be lost before they can survive in the ocean.
C.
Caterpillar biomass peaks before chicks hatch.
D.
Adults are prevented from ever reaching ocean feeding areas.
Question 2
What property makes carbon dioxide and methane greenhouse gases?
A.
They increase the rate of photosynthesis in all ecosystems.
B.
They absorb and re-emit long-wave infrared radiation.
C.
They reflect most incoming short-wave solar radiation.
D.
They break down atmospheric nitrogen and oxygen.
Question 3
A positive correlation between atmospheric carbon dioxide concentration and global temperature means that the two variables tend to show what relationship?
A.
One variable tends to increase as the other variable decreases.
B.
Both variables tend to increase together or decrease together.
C.
Both variables remain constant over the same time interval.
D.
One variable always directly causes the other variable to change.
Question 4
How can stronger stratification of the surface ocean reduce marine primary production?
A.
It reduces mixing of nutrient-rich deep water into the well-lit surface layer.
B.
It makes all surface water denser than cold deep water.
C.
It causes nitrate and phosphate to be destroyed by high salinity.
D.
It increases oxygen diffusion into deep water where photosynthesis is greatest.
Question 5
What is phenology?
A.
The study of the timing of recurring biological events.
B.
The combustion of stored carbon in boreal forest soils.
C.
The movement of deep nutrient-rich water to the ocean surface.
D.
The measurement of infrared absorption by greenhouse gases.
Question 6
Outline one effect of sea ice loss on walruses in the Arctic. [2]
Question 7
What is an example of a positive feedback cycle in global warming?
A.
Photosynthesis stops all carbon dioxide accumulation in air.
B.
Nitrogen gas absorbs more infrared radiation as temperature rises.
C.
Cloud formation always reflects enough radiation to stop warming.
D.
Melting ice exposes darker ocean, increasing absorption of solar radiation.
Question 8
In boreal forests, what is meant by legacy carbon combustion?
A.
Respiration of carbon fixed by trees during the same day.
B.
Absorption of carbon dioxide by new conifer needles after fire.
C.
Burning of carbon stored over many previous years in wood, litter, peat or soil.
D.
Dissolution of carbon dioxide in cold boreal lakes.
Question 9
What direct effect does ocean acidification have on reef-forming corals?
A.
It increases landfast ice stability around coral reefs.
B.
It causes corals to absorb methane instead of carbon dioxide.
C.
It increases albedo and prevents bleaching.
D.
It reduces carbonate ion availability and suppresses calcification.
Question 10
What feature of restored peat-forming wetlands makes them effective for long-term carbon sequestration?
A.
Dry peat burns rapidly and releases stored carbon dioxide.
B.
Non-native monocultures always maximize biodiversity and resilience.
C.
All decomposition is stopped permanently by high light intensity.
D.
Waterlogged, low-oxygen soils slow decomposition of plant material.
Question 11
Why can photoperiod remain a reliable seasonal cue even when climate warms?
A.
It is the same at all latitudes on every date.
B.
It increases whenever spring temperatures increase.
C.
It depends on day length, which is not shifted by climate change.
D.
It directly measures the biomass of caterpillars.
Question 12
In a warmer spring, what phenological mismatch can reduce great tit chick survival?
A.
Peak caterpillar biomass occurs before the chicks’ greatest food demand.
B.
Corals lose symbiotic algae before birds migrate.
C.
Spruce bark beetles complete fewer generations per year.
D.
Photoperiod stops changing during the nesting season.
Question 13
In the Arctic mouse-ear chickweed and reindeer example, what causes disruption of synchrony?
A.
Chickweed uses snow cover to select owl plumage colour.
B.
Plant growth responds to warming while reindeer arrival may not advance equally.
C.
Both plant growth and migration are controlled only by ocean pH.
D.
Reindeer cause landfast ice to break out earlier each spring.
Question 14
How can warming increase damage caused by spruce bark beetles?
A.
It increases resin flow in drought-stressed trees.
B.
It prevents all adult beetles from emerging at the same time.
C.
It shortens development time and can allow more generations per year.
D.
It removes the larval stage from the beetle life cycle.
Question 15
How can reduced snow cover affect evolution in tawny owls, Strix aluco?
A.
All plumage variation disappears because colour is not heritable.
B.
Brown plumage variants may have higher fitness, increasing alleles associated with brown colour.
C.
Snow cover directly prevents reproduction in every colour variant.
D.
Grey owls immediately change into brown owls during a mild winter.
Question 16
State one anthropogenic source of carbon dioxide.
[1]
Outline why methane is considered a greenhouse gas.
[1]
Question 17
Define albedo.
[1]
Explain how loss of snow and ice can act as a positive feedback in global warming.
[1]
Question 18
State the cause of ocean acidification.
[1]
Outline how rising water temperature can lead to coral reef ecosystem collapse.
[1]
Question 19
Define phenology.
[1]
State two phenological events in deciduous trees.
[1]
Question 20
Using tawny owls, Strix aluco, as an example, outline how climate change can alter selection pressures. [3]
Question 21
What combined effect of climate change can promote spruce bark beetle outbreaks?
A.
Faster beetle development and reduced host-tree defences during drought.
B.
Lower beetle reproduction and increased resin flow in all trees.
C.
Reduced photosynthesis in beetles and increased calcification in spruce.
D.
Earlier ocean upwelling and greater carbonate ion availability.
Question 22
What condition is necessary for climate change to cause evolution in a population?
A.
All individuals must respond identically to the new climate.
B.
Only non-heritable behaviours must change during one season.
C.
The population must stop reproducing for several generations.
D.
Climate change must alter the relative survival or reproduction of heritable variants.
Question 23
Antarctic ice-core data show that atmospheric carbon dioxide concentration and global temperature have varied together over long time scales.
Distinguish between correlation and causation.
[1]
State one type of evidence, other than correlation in ice cores, that supports a causal link between carbon dioxide and warming.
[1]
Question 24
A boreal forest has experienced warmer summers and reduced winter snowfall for several decades.
State what is meant by net carbon loss in a forest.
[1]
Explain how warmer temperatures and reduced winter snowfall can contribute to a tipping point in boreal forests.
[1]
Question 25
State what is meant by upwelling.
[1]
Explain why reduced upwelling can decrease energy flow through marine food chains.
[1]
Question 26
Distinguish between photoperiod and temperature as cues for phenological events. [3]
Question 27
Explain how climate change can disrupt synchrony between great tits, Parus major, and caterpillars in north European forests. [3]
Question 28
Explain how climate change can reduce synchrony between Arctic mouse-ear chickweed, Cerastium arcticum, and migrating reindeer, Rangifer tarandus. [3]
Question 29
Outline how climate change can increase the number of spruce bark beetle life cycles within a year. [3]
Question 30
Explain why drought-stressed spruce trees may be more vulnerable to bark beetle attack. [3]
Question 31
The graph shows atmospheric carbon dioxide concentration and global mean temperature anomaly over a long time period.
Describe the relationship between atmospheric carbon dioxide concentration and temperature anomaly shown in the graph.
[1]
Identify whether the relationship is a positive or negative correlation.
[1]
Explain why these data alone do not prove that carbon dioxide causes warming.
[1]
Question 32
A model was used to compare surface albedo and absorbed solar radiation before and after seasonal ice melt.
State the change in albedo after ice melt shown in the model.
[1]
Describe the change in absorbed solar radiation after ice melt.
[1]
Explain how the changes shown can form a positive feedback cycle.
[1]
Question 33
A survey recorded the elevation range of a tropical-zone montane bird species in New Guinea at two times separated by several decades.
| Survey year | Lower elevation limit / m | Upper elevation limit / m |
|---|---|---|
| 1970 | 1250 | 2700 |
| 2015 | 1650 | 3100 |
State the direction of the range shift shown.
[1]
Describe the change in the lower and upper limits of the species range.
[1]
Suggest why species living near mountain summits may be at particular risk from climate warming.
[1]
Question 34
A restoration project compared three land-management options for a degraded catchment: non-native plantation, native forest regeneration and peatland rewetting.
| Restoration option | Biomass C / t ha⁻¹ | Soil or peat C / t ha⁻¹ | Biodiversity index / 0–1 | Main risk |
|---|---|---|---|---|
| Non-native plantation | 110 | 55 | 0.38 | High fire risk |
| Native forest regeneration | 82 | 96 | 0.81 | Low fire risk |
| Peatland rewetting | 24 | 238 | 0.67 | Drainage failure risk |
Identify the option with the greatest carbon stored after the monitoring period.
[1]
Compare the biodiversity outcomes of the three options.
[1]
Evaluate why carbon storage alone may be insufficient for choosing the best restoration strategy.
[1]
Question 35
Researchers investigated the timing of budburst in a deciduous tree species. The scatter graph shows mean spring temperature and day of year of budburst for several years.
Describe the relationship between mean spring temperature and budburst date.
[1]
State what a high R² value for this relationship would indicate.
[1]
Suggest why some variation in budburst date may remain unexplained by temperature.
[1]
Question 36
A conservation agency must choose between planting a fast-growing non-native tree plantation and regenerating native forest on degraded land.
Compare these two approaches as methods of carbon sequestration.
[1]
Question 37
Define fitness in the context of natural selection.
[1]
Explain why a change in the frequency of tawny owl colour variants over generations is evidence of evolution, not acclimatization.
[1]
Question 38
The graph shows annual net ecosystem carbon exchange in a boreal forest together with the number of severe fire years. Negative values indicate net carbon accumulation and positive values indicate net carbon loss.
Identify the period when the forest acts mainly as a carbon sink.
[1]
Describe the relationship between severe fire years and net ecosystem carbon exchange.
[1]
Suggest why repeated severe fires could shift the forest past a tipping point.
[1]
Question 39
The graph shows the dates of peak caterpillar biomass and peak food demand by great tit chicks in a woodland over several years.
Describe the change in synchrony between caterpillars and great tit chicks.
[1]
Identify the years in which chicks are most likely to experience food shortage.
[1]
Explain how climate change could produce the pattern shown.
[1]
Question 40
A study monitored spruce bark beetle development at different mean summer temperatures.
Describe the effect of temperature on development time.
[1]
Use the data to identify the temperature range in which two generations per year become possible.
[1]
Suggest two reasons why warmer, drier years can increase tree mortality from beetles.
[1]
State one possible ecosystem consequence of a beetle outbreak.
[1]
Question 41
A long-term study recorded the frequency of brown plumage in tawny owls, Strix aluco, and the number of days with snow cover each winter.
Describe the relationship between snow cover and frequency of brown owls.
[1]
Explain why this pattern could be an example of natural selection.
[1]
State one further piece of evidence needed to strengthen the conclusion that evolution has occurred.
[1]
Question 42
Outline how peat-forming wetlands sequester carbon.
[1]
Evaluate afforestation, forest regeneration and peatland restoration as approaches to carbon sequestration.
[1]
Question 43
Researchers compared two models predicting the arrival date of migrating reindeer and the peak spring growth of Arctic mouse-ear chickweed. One model used temperature as the main predictor and the other used photoperiod.
Identify which biological event is more closely associated with temperature in the data.
[1]
Identify which biological event changes least between years.
[1]
Evaluate how the data support the claim that different cues can disrupt synchrony under climate change.
[1]
Question 44
Outline two anthropogenic causes of increased atmospheric greenhouse gases.
[1]
Discuss how positive feedback cycles can amplify global warming.
[1]
Question 45
Describe two effects of increased carbon dioxide on seawater chemistry and coral calcification.
[1]
Explain how climate change can lead to coral reef ecosystem collapse.
[1]
Question 46
Describe how boreal forests normally act as carbon sinks.
[1]
Explain how climate change can cause a boreal forest to change from net carbon accumulation to net carbon loss.
[1]
Question 47
Distinguish between temperature and photoperiod as cues for phenological events.
[1]
Discuss how climate change can disrupt synchrony between interacting populations, using named examples.
[1]
Question 48
Outline how temperature affects insect life cycles.
[1]
Explain how climate change can increase spruce bark beetle outbreaks and their effects on forests.
[1]
Question 49
Define evolution and fitness.
[1]
Evaluate how changes in snow cover could lead to evolution in tawny owl, Strix aluco, populations.
[1]
Question 50
Describe how phenology can be investigated using budburst data in deciduous trees.
[1]
Discuss how climate change can affect ecosystems through phenological change, insect life cycles and evolutionary responses.
[1]
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