Question 1
A student describes the habitat of a shore crab as “under stones in the splash zone of a rocky Atlantic coast ecosystem”. What part of this description is the physical location within the habitat?
A.
Under stones
B.
Rocky coast ecosystem
C.
Atlantic coast
D.
Shore crab
Question 2
Reef-building corals contain photosynthetic algae in their tissues. What condition is therefore required for coral reef formation?
A.
Deep water that excludes wave action
B.
Low salinity from river outflow
C.
Clear shallow water with sufficient light
D.
Acidic water that dissolves minerals
Question 3
Marram grass, Ammophila arenaria, grows on sand dunes where wind increases evaporation from leaves. What adaptation most directly reduces water loss in windy conditions?
A.
Flowering stems above the dune surface
B.
Deep roots that anchor the plant
C.
Rhizomes that spread through sand
D.
Sunken stomata within rolled leaves
Question 4
A freshwater invertebrate is found only in fast-flowing streams and is absent from stagnant ponds. What abiotic variable is most likely limiting its distribution?
A.
Availability of mates
B.
Density of predators
C.
Dissolved oxygen concentration
D.
Number of competitors
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Question 5
Merriam’s kangaroo rat, Dipodomys merriami, lives in hot deserts. What adaptation reduces its need to drink free water?
A.
Producing dilute urine during the day
B.
Obtaining metabolic water from dry seeds
C.
Laying eggs on leaves above pools
D.
Having adhesive pads for climbing wet leaves
Question 6
Grey mangrove, Avicennia marina, grows in waterlogged mud where oxygen diffuses slowly. What structure is most directly adapted for oxygen uptake by roots?
A.
Pneumatophores projecting above the mud
B.
Buoyant propagules dispersed by seawater
C.
Salt glands in leaves
D.
Thick waxy cuticle on leaf surfaces
Question 7
A student records the habitat of a small woodland snail as “forest”.
State what is meant by a habitat.
[1]
Outline two ways in which the habitat description could be made more biologically useful.
[2]
Question 8
A belt transect across a meadow shows that a plant species has its highest percentage cover where soil pH is low and is absent where soil pH is high. What conclusion is best supported by these data?
A.
High soil pH increases the plant's tolerance range
B.
Low soil pH has been proven to cause faster photosynthesis
C.
Low soil pH is correlated with greater abundance of the plant
D.
Soil pH is a biotic factor controlling competition
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Question 9
The graph shows the abundance of a shore plant in relation to soil salinity.
A.
The plant is absent only where salinity is intermediate
B.
The plant grows equally well at all salinities
C.
The plant's distribution is independent of soil salinity
D.
The plant has greatest performance at intermediate salinity
Question 10
A biome climate graph has mean annual temperature on the horizontal axis and annual precipitation on the vertical axis. A region has high mean annual temperature and very low annual precipitation. What natural ecosystem type is most likely to develop?
A.
Taiga
B.
Temperate forest
C.
Hot desert
D.
Tropical forest
Question 11
Unrelated desert plants on different continents often have reduced leaves or spines and water-storing tissues. What process best explains this similarity?
A.
Random mating between the plant populations
B.
Inheritance from one recent desert ancestor
C.
Artificial selection by human cultivation
D.
Convergent evolution under similar selection pressures
Question 12
Marram grass, Ammophila arenaria, grows on coastal sand dunes where the substrate is unstable, freely draining and exposed to wind.
State one abiotic challenge for plants growing on sand dunes.
[1]
Explain how two adaptations of marram grass increase survival in this habitat.
[3]
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Question 13
Reef-building corals contain photosynthetic algae living in their tissues.
Outline the mutualistic relationship between reef-building corals and their algae.
[2]
Explain why shallow, clear water is required for coral reef formation.
[2]
Question 14
Merriam’s kangaroo rat, Dipodomys merriami, lives in hot deserts. The red-eyed tree frog, Agalychnis callidryas, lives in tropical rainforests.
Describe one adaptation of Dipodomys merriami to hot desert conditions.
[2]
Describe one adaptation of Agalychnis callidryas to tropical rainforest conditions.
[2]
Question 15
Students compared two descriptions of where the snail Littorina littorea was found on a rocky coast. They also recorded snail abundance and environmental conditions at positions from the upper shore to the lower shore.
Item | Position / description | Moisture / % | Snail abundance / snails |
|---|---|---|---|
Description 1 | rocky coast | — | — |
Description 2 | damp crevices on a rocky shore in the marine intertidal zone | — | — |
Transect point 1 | upper shore | 20 | 2 |
Transect point 2 | upper-mid shore | 35 | 5 |
Transect point 3 | mid-shore crevice zone | 80 | 18 |
Transect point 4 | lower-mid shore | 55 | 9 |
Transect point 5 | lower shore | 30 | 3 |
Identify the more biologically useful habitat description from the stimulus.
[1]
Describe the distribution of Littorina littorea across the shore using the data.
[2]
Suggest one abiotic factor that could limit the distribution of this snail on the upper shore.
[1]
Question 16
Four coastal sites were surveyed to determine whether reef-building corals were likely to form a coral reef. Measurements were made during the warm season.
Site | Mean depth / m | Water clarity / m | Mean temperature / | Mean pH | Mean salinity / ppt | Coral cover / % |
|---|---|---|---|---|---|---|
A | 3 | 9 | 28.6 | 8.07 | 34.6 | 28 |
B | 1 | 15 | 29.2 | 8.20 | 35.0 | 67 |
C | 6 | 2 | 28.8 | 8.01 | 33.1 | 8 |
D | 25 | 11 | 28.0 | 8.03 | 34.8 | 4 |
Identify the site most suitable for coral reef formation.
[1]
Using the data, suggest why the deep site has low coral cover.
[1]
Explain why low water clarity can prevent reef formation.
[2]
State one abiotic condition, other than depth and clarity, required for coral reef formation.
[1]
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Question 17
The kapok tree, Ceiba pentandra, grows in tropical rainforest where soils can be shallow and rainfall is high. What pair of adaptations is correctly matched to these conditions?
A.
Nocturnal foraging and concentrated urine to conserve water
B.
Salt glands for ion excretion and pneumatophores for mud aeration
C.
Buttress roots for support and drip tips to shed water
D.
Deep taproot for permafrost and white fur for insulation
Question 18
Adult fish of one species feed in many parts of a river, but eggs hatch only in shallow gravel beds with high dissolved oxygen. What best explains the restricted distribution of breeding adults during spawning season?
A.
Adults lose all adaptations outside gravel beds
B.
A reproductive life stage has a narrower abiotic tolerance
C.
Gravel beds remove all biotic selection pressures
D.
Distribution is unrelated to abiotic variables during reproduction
Question 19
A belt transect was used across a woodland edge. At each quadrat, percentage cover of a shade-tolerant herb and light intensity were recorded.
Describe the relationship between light intensity and the percentage cover of the herb.
[2]
Suggest why light intensity may be a limiting factor for the distribution of this herb.
[1]
State why these transect data alone do not prove that light intensity causes the distribution pattern.
[1]
Question 20
A biome climate graph shows the natural ecosystem type expected at different combinations of mean annual temperature and annual precipitation.
Identify the biome most likely to develop at the unlabelled point.
[1]
Outline why temperature and precipitation are useful predictors of terrestrial biome distribution.
[2]
State one reason why the boundaries between biomes on such graphs are not sharp lines in nature.
[1]
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Question 21
Grey mangrove, Avicennia marina, grows in saline, waterlogged mud where oxygen diffuses slowly to roots.
State one abiotic factor in mangrove swamps that limits tree growth.
[1]
Explain how two adaptations of Avicennia marina allow it to grow in mangrove swamps.
[3]
Question 22
Unrelated plant families in hot deserts may include species with succulent stems, spines and reduced leaves.
Define convergent evolution.
[1]
Explain why similar plant forms can evolve in hot deserts on different continents.
[3]
Question 23
Two regions have similar annual precipitation. Region X has a very low mean annual temperature and a short growing season. Region Y has a high mean annual temperature, intense sunlight and large day-night temperature variation.
Region | Annual precipitation / mm yr | Mean annual temperature / | Growing season / days | Mean daily solar radiation / MJ m day | Mean day-night temperature range / |
|---|---|---|---|---|---|
X | 180 | -10 | 60 | 7 | 8 |
Y | 180 | 30 | 300 | 28 | 24 |
Deduce the most likely terrestrial biome in each region.
[2]
Explain why similar low precipitation does not lead to the same biome in the two regions.
[2]
Question 24
Marram grass, Ammophila arenaria, grows on coastal sand dunes. Students measured leaf rolling and soil water content along a transect from the seaward face of a dune to a more stable inland area.
State the relationship between soil water content and leaf opening width shown in the graph.
[1]
Explain how rolling of marram grass leaves is an adaptation to sand dune conditions.
[2]
Suggest one other adaptation of Ammophila arenaria to unstable sand dunes.
[1]
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Question 25
Grey mangrove, Avicennia marina, grows in muddy intertidal swamps. A student measured the density of pneumatophores and the dissolved oxygen concentration in mud at different distances from a tidal creek.
Distance from tidal creek / m | Dissolved oxygen / mg dm | Mean pneumatophore density / m |
|---|---|---|
0 | 2.8 | 12 |
5 | 2.2 | 20 |
10 | 1.7 | 29 |
15 | 1.1 | 39 |
20 | 0.5 | 50 |
Calculate the increase in mean pneumatophore density between the site closest to the creek and the site farthest from the creek.
[1]
Describe the relationship between dissolved oxygen concentration in the mud and pneumatophore density.
[1]
Explain why pneumatophores are useful in the habitat shown.
[2]
State one adaptation of Avicennia marina to high salinity.
[1]
Question 26
A biome climate diagram was used to classify three locations according to mean annual temperature and annual precipitation.
Identify the biome represented by point X.
[1]
State the two climatic variables used in the diagram to predict biome distribution.
[1]
Explain why a tropical forest is likely to develop at point Z rather than grassland.
[2]
Question 27
Two named animals were studied in their natural habitats: Merriam’s kangaroo rat, Dipodomys merriami, in a hot desert and the red-eyed tree frog, Agalychnis callidryas, in a tropical rainforest.
Species | Habitat | Day temperature / | Night temperature / | Relative humidity / % | Annual rainfall / mm | Main activity period | Typical habitat position |
|---|---|---|---|---|---|---|---|
Merriam’s kangaroo rat (Dipodomys merriami) | hot desert | 42 | 18 | 15 | 120 | mainly nocturnal | on the ground in burrows |
Red-eyed tree frog (Agalychnis callidryas) | tropical rainforest | 29 | 24 | 90 | 2500 | mainly nocturnal | on leaves and branches in trees |
State one abiotic difference between the two habitats shown.
[1]
Compare the activity periods of the two species.
[1]
Explain how nocturnal activity benefits the kangaroo rat in the desert.
[2]
Suggest how adhesive toe pads are useful to the red-eyed tree frog in its habitat.
[1]
Question 28
The distribution of an aquatic insect larva was investigated in streams with different dissolved oxygen concentrations.
Describe the pattern shown by the tolerance curve.
[2]
Explain how the larva’s adaptations could determine its distribution in streams.
[2]
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Question 29
A student investigates whether soil pH affects the distribution of a wild plant in a semi-natural meadow. The student places quadrats at sites where the plant is already common and measures soil pH once in each quadrat.
Identify one weakness in the sampling method.
[1]
Suggest two improvements that would allow a stronger correlation between soil pH and plant distribution to be tested.
[2]
State one conclusion that would be justified if the plant occurred only in quadrats with low soil pH.
[1]
Question 30
A coastal development is proposed near a tropical lagoon containing reef-building corals. The development may increase sediment runoff and freshwater input into the lagoon.
Explain how increased sediment runoff could reduce coral reef formation.
[2]
Suggest two further abiotic variables that should be monitored to assess whether reef formation is likely to continue.
[2]
Question 31
The abundance of a freshwater mayfly nymph was recorded in streams with different dissolved oxygen concentrations. Mayfly nymphs require oxygen from the water for aerobic respiration.
Estimate the dissolved oxygen concentration at which mayfly abundance is greatest.
[1]
Describe the zone of physiological stress at low dissolved oxygen concentration.
[1]
Explain why dissolved oxygen can act as a limiting factor for this animal.
[2]
State why these data alone do not prove that dissolved oxygen causes the distribution pattern.
[1]
Question 32
A woodland herb was sampled along a transect from acidic soil near conifer trees to less acidic soil near a path. Students measured soil pH with a probe and estimated percentage cover of the herb in quadrats at regular intervals.
Identify the range of soil pH over which the herb has its highest percentage cover.
[1]
Analyse the evidence that soil pH affects the distribution of the herb.
[2]
Evaluate one limitation of the method used by the students.
[1]
Suggest one improvement to increase confidence in the conclusion.
[1]
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Question 33
Plants from three hot desert ecosystems on different continents were compared. The plants are not closely related, but they live under similar abiotic conditions.
Trait | North America | Africa | Australia |
|---|---|---|---|
Plant group | saguaro cactus | desert euphorbia | Australian saltbush |
Family | Cactaceae | Euphorbiaceae | Amaranthaceae |
Mean annual precipitation / mm | 45 | 30 | 65 |
Leaf surface area / per leaf | 0.1 | 0.2 | 0.8 |
Root spread / m | 12 | 10 | 11 |
Water-storage tissue | present | present | present |
State the abiotic condition common to the three ecosystems.
[1]
Identify one similar adaptation shown by the unrelated plant groups.
[1]
Discuss how the table provides evidence for convergent evolution.
[2]
Question 34
A region currently supports temperate forest. Climate projections predict changes in mean annual temperature and annual precipitation by the end of the century.
Identify the biome most likely to develop if the projected climate is reached and no other factors limit the change.
[1]
State the direction of change in each climatic variable shown by the projection.
[1]
Explain why reduced precipitation may prevent closed forest from persisting.
[2]
Question 35
Marram grass, Ammophila arenaria, grows on exposed coastal sand dunes where the surface sand is mobile, drains rapidly and is often affected by salt spray.
Describe the habitat of marram grass using both physical location and ecosystem type.
[2]
I.
Explain how rolled leaves reduce water loss in this habitat.
[1]
II.
Explain how rhizomes and deep roots increase survival on sand dunes.
[1]
A student claims that these features are adaptations produced because individual marram plants need to survive on dunes. Evaluate this claim.
[3]
Question 36
Grey mangrove, Avicennia marina, grows in intertidal mud where roots may be waterlogged and exposed to seawater.
I.
Identify two abiotic factors that make mangrove mud a difficult habitat for trees.
[1]
II.
Distinguish between an abiotic factor and a biotic factor in a mangrove swamp.
[1]
Explain how two adaptations of grey mangrove roots help the tree survive in waterlogged saline mud.
[3]
Suggest why mangrove propagules that float may increase the distribution of the species along a coastline.
[2]
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Question 37
A woodland herb is abundant in shaded, moist leaf litter but absent from an adjacent open grassland. A student investigates whether light intensity is associated with its distribution.
Distance along transect / m | Light intensity / lux | Herb abundance / % cover |
|---|---|---|
0 | 110 | 92 |
5 | 160 | 88 |
10 | 290 | 74 |
15 | 430 | 61 |
20 | 580 | 37 |
25 | 760 | 14 |
30 | 980 | 4 |
35 | 1160 | 0 |
I.
Define range of tolerance.
[1]
II.
State why light intensity could be a limiting factor for this herb.
[1]
Explain how transect data could be collected to test the association between light intensity and distribution of the herb.
[3]
The data show a negative correlation between light intensity and herb abundance. Discuss whether this proves that high light intensity causes the herb to be absent from grassland.
[2]
Question 38
Long-term monitoring of a shallow reef recorded summer sea temperature, water clarity and percentage cover of live reef-building coral. A heatwave occurred during one year of the study.
Year | Summer sea temperature / | Water clarity / m | Live coral cover / % |
|---|---|---|---|
2014 | 28.6 | 11.8 | 63 |
2015 | 28.7 | 11.9 | 62 |
2016 | 31.6 | 10.8 | 58 |
2017 | 29.0 | 9.5 | 34 |
2018 | 28.8 | 10.7 | 35 |
Calculate the percentage-point decrease in live coral cover from the year before the heatwave to the year after the heatwave.
[1]
Describe the evidence that temperature was associated with the decrease in live coral cover.
[1]
Explain why prolonged high temperature can reduce coral reef formation.
[2]
Evaluate whether the data show temperature was the only factor affecting coral cover.
[1]
Question 39
A fish species feeds as an adult in a wide range of river habitats, but its eggs are found only in some spawning sites. Researchers compared abiotic conditions at sites where eggs were present and absent.
Site | Gravel size / mm | Dissolved oxygen / mg L | Current speed / m s | Adult sightings / count | Eggs present |
|---|---|---|---|---|---|
1 | 5 | 7.8 | 0.20 | 9 | No |
2 | 22 | 8.1 | 0.35 | 13 | Yes |
3 | 12 | 8.0 | 0.30 | 8 | No |
4 | 23 | 8.4 | 0.60 | 12 | Yes |
5 | 35 | 8.5 | 0.50 | 15 | No |
6 | 23 | 8.8 | 0.75 | 11 | Yes |
7 | 48 | 8.2 | 0.80 | 14 | No |
8 | 60 | 8.7 | 0.90 | 10 | No |
Identify the abiotic variable with the narrowest apparent tolerance range for egg presence.
[1]
Compare the distribution of adult fish sightings with the distribution of eggs.
[1]
Suggest why the requirements of the egg stage can restrict the distribution of the whole species.
[2]
Question 40
Reef-building corals contain mutualistic photosynthetic algae in their tissues. A coastal development is proposed near a shallow tropical bay where a small coral reef is forming.
I.
Outline the mutualistic relationship between reef-building corals and their algae.
[2]
II.
State one reason why reef formation is strongest in shallow clear water.
[1]
Explain how each of pH, salinity and temperature can limit coral reef formation.
[3]
Discuss whether the bay is likely to remain suitable for reef formation if construction increases suspended sediment and freshwater runoff.
[2]
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Question 41
The graph shows broad regions occupied by six terrestrial biomes when mean annual temperature and annual precipitation are compared.
Biome | Mean annual temperature / | Annual precipitation / mm yr |
|---|---|---|
Tundra | to | 100 to 500 |
Boreal forest | to | 250 to 900 |
Temperate grassland | to | 250 to 1000 |
Temperate forest | to | 600 to 2000 |
Hot desert | to | 0 to 300 |
Tropical rainforest | to | 2000 to 4000 |
I.
Define the term biome.
[1]
II.
Identify the two climatic variables used to predict terrestrial biome distribution in the graph.
[1]
Explain why a hot desert rather than a forest is likely to develop where precipitation is very low.
[2]
Evaluate the use of only mean annual temperature and annual precipitation to predict the biome of a site.
[3]
Question 42
Creosote bush, Larrea tridentata, is a hot desert plant. Red-eyed tree frog, Agalychnis callidryas, is an animal of tropical rainforests.
I.
Outline two abiotic conditions typical of hot deserts.
[1]
II.
Outline two abiotic conditions typical of tropical rainforests.
[1]
III.
State the main limiting factor for many plants in hot deserts.
[1]
Compare and contrast adaptations of the creosote bush and red-eyed tree frog to their habitats.
[3]
Suggest why a feature that is adaptive in one of these habitats may be disadvantageous in the other.
[2]
Question 43
A salt-marsh plant is surveyed along a belt transect from a tidal creek to higher ground. Soil salinity and percentage cover of the plant are recorded in quadrats.
I.
Identify the likely optimum salinity range for the plant from the pattern shown.
[1]
II.
Explain why plant cover is low at both low and high salinity extremes.
[2]
Evaluate salinity as the limiting factor controlling the distribution of this plant along the transect.
[3]
Suggest two improvements to the investigation that would make conclusions about the plant's tolerance range more reliable.
[2]
Question 44
Unrelated desert plant species on different continents often have small leaves, spines or water-storing tissues despite belonging to different plant families.
I.
Define convergent evolution.
[1]
II.
State one abiotic selection pressure common to hot deserts.
[1]
Explain how similar abiotic conditions can lead to similar adaptations in unrelated desert plants.
[3]
Discuss why ecosystems within the same terrestrial biome may have similar communities even when they contain different species.
[2]
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Question 45
A freshwater invertebrate is found mainly in fast-flowing streams with gravel beds. It is absent from nearby stagnant ponds.
I.
Identify two abiotic variables that could affect the distribution of this invertebrate.
[1]
II.
State why a requirement of one life stage can restrict the distribution of the whole species.
[1]
Explain why dissolved oxygen and substrate type may be linked to the invertebrate's adaptations.
[3]
Evaluate the conclusion that dissolved oxygen is the only factor determining the invertebrate's distribution.
[2]
Question 46
A marine reserve contains a coral reef near the mouth of a river. Managers are concerned about warmer water, reduced pH and increased sediment during storms.
I.
Explain why the coral-algal mutualism makes coral reefs sensitive to water clarity.
[2]
II.
State one way storm runoff can change salinity around the reef.
[1]
Explain how warmer water and lower pH could interact to reduce reef growth.
[3]
Evaluate whether planting mangroves upstream would be sufficient on its own to protect the reef.
[2]
Question 47
In tropical rainforests, light intensity is high above the canopy but low at the forest floor. Kapok trees, Ceiba pentandra, and red-eyed tree frogs, Agalychnis callidryas, live in this biome.
I.
Outline two abiotic conditions of tropical rainforests other than high rainfall.
[1]
II.
Explain why competition for light is strong among rainforest plants.
[2]
Explain how two adaptations of the kapok tree are suited to rainforest conditions.
[2]
Discuss how adaptations of the red-eyed tree frog reduce the challenges of living on wet rainforest vegetation.
[3]
Question 48
A region currently supports temperate forest. Climate projections suggest warmer mean annual temperature and lower annual precipitation over the next century.
I.
Using the graph, predict the type of biome that may become more likely in the region.
[1]
II.
State why a change in biome does not require all original species to disappear immediately.
[1]
Explain how reduced precipitation could shift the community from forest toward grassland.
[3]
Evaluate the reliability of predicting future biome distribution from this climate diagram alone.
[3]
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