IB Biology SL B4.1 Adaptation to Environment Questions

Practise IB Biology SL B4.1 by linking organism distribution and adaptations to abiotic limits, tolerance ranges, climate and biome conditions.

Exam points

Define habitat and distinguish it from a biome and the biosphere by the ecological scale and environment each describes.
Identify abiotic variables such as water, light, nutrients, salinity or temperature and explain how deficiency or excess limits survival, growth or reproduction.
Use transects and ecological data to relate measured abiotic gradients to organism distribution or abundance.
Interpret tolerance data to identify critical, optimum and stress ranges, compare species and predict effects on survival or distribution.
Relate warm, shallow, clear, sunlit and suitable-pH water to coral-reef formation, and interpret bleaching or coral-cover evidence about temperature thresholds.
Identify terrestrial biomes from temperature, rainfall and climograph patterns.
Compare biome climate, vegetation and productivity, and relate latitude or seasonal temperature and rainfall to global distribution.
Compare desert-plant water-saving features with mangrove salt and waterlogging adaptations, including roots, storage, reduced leaves and pneumatophores.
Relate desert-animal features such as pale colouration and large ears to heat balance, camouflage and survival in hot conditions.
Explain how tropical-rainforest pitcher plants capture insects to supplement mineral nutrients in nutrient-poor soils.

Covered syllabus points

B4.1.1—Habitat definition B4.1.2—Adaptations to abiotic environment B4.1.3—Abiotic variables affecting distribution B4.1.4—Range of tolerance of limiting factor B4.1.5—Coral reef formation conditions B4.1.6—Terrestrial biome distribution B4.1.7—Biomes B4.1.8—Adaptations to hot deserts and tropical rainforest

[Maximum number: 2]

The distribution of native grasses in a temperate arid region of Mendoza, Argentina, was studied in six habitats (I to VI) at different altitudes. The table shows the presence (+) or absence (-) of the species in each habitat.

(a)

Suggest one abiotic factor, other than altitude, that could be affecting the distribution of species in the different habitats.

[ 1 ]

(b)

Define habitat.

[ 1 ]

[Maximum number: 2]

The image shows a cast of the lower surface of a leaf from a busy Lizzie (Impatiens walleriana) plant as seen under a light microscope with a magnification of $600 \times$ .

Circular microscope field of leaf epidermis showing irregular interlocking cells, dark nuclei and several pairs of guard cells around elongated pores.

Explain one feature of tree roots that help trees to survive in mangrove swamps.

[Maximum number: 2]

The tundra ecosystem in Finnish Lapland has a short growing season and a mean temperature of $-2.0^{\circ} \mathrm{C}$ . It is also naturally grazed by herbivores such as reindeer (Rangifer tarandus). Different quadrats were set up to include and exclude the reindeer in both normal and warmed temperatures. Open-topped warming chambers were used to heat both the soil and air in the warmed quadrats. The graph shows the changes in plant richness over five years.

Identify two abiotic limiting factors on plant growth in a tundra ecosystem.

[Maximum number: 1]

Define habitat.

[Maximum number: 8]

Fires are a natural phenomenon in some forest ecosystems, so plants evolve to become fire-adapted. The Northern Jarrah Forest in southwest Australia is an example. The seeds of many species germinate after forest fires, when there is less competition for resources from existing plants.

The effect of temperature on germination was measured in species that occur commonly in the Northern Jarrah Forest. The graphs show results for eight species across the range of soil temperatures expected in this ecosystem. Four replicates of 25 seeds were sown at each temperature. Statistical modelling was used to predict the overall relationship between temperature and germination, and to estimate the optimum temperature ( $\mathrm{T}_{\text {opt }}$ ) and maximum temperature ( $\mathrm{T}_{\max }$ ) at which germination commonly occurs. The eight species were then divided into two groups according to the effects of temperature on germination.

Group 1

Group 2

(a)

Identify the species in which $T_{\text {opt }}$ is lowest.

[ 1 ]

(b)

Calculate the range for $T_{\max }$ among the eight species.

[ 1 ]

$10 / 9.5^{\circ} \mathrm{C}$

OR

20 to $30^{\circ} \mathrm{C} / 20-30^{\circ} \mathrm{C}$

OR

30 to $20^{\circ} \mathrm{C} / 30-20^{\circ} \mathrm{C}$ ;

Accept answers in the range of 9 to $10^{\circ} \mathrm{C}$ .

Accept range of 20 to $29^{\circ} \mathrm{C}$ , 21 to $30^{\circ} \mathrm{C}$ Units required.

Working ( 30-20=10 ) not required because only one mark can be earned.

(c)

Analyse the graphs to find the key difference between species in Group 1 and Group 2.

[ 1 ]

larger gap/wider tolerance between $\mathrm{T}_{\text {opt }}$ and $\mathrm{T}_{\max }$ in Group 2 / vice versa / OWTTE OR

the species in group 2 show a higher germination rate than the species in group 1 OR

(generally)species in group 2 can tolerate warmer temperatures than group 1;

(d)

Predict, giving reasons, when germination would start in Kennedia prostrata, following a forest fire at the start of summer.

[ 3 ]

Prediction

a. in autumn/April/March;

Reasons 2 max

b. when temperature has dropped below $\mathrm{T}_{\text {max }}$ (for K. prostrata)

OR

when temperature has reached Topt (for K. prostrata);

c. when $\mathrm{T}_{\max }$ in K. prostrata is $21 / 22^{\circ} \mathrm{C}$ (after the forest fire);

d. when soil moisture has risen;

2 marks max for the reasons.

c: mark is earned for citing the $\mathrm{T}_{\max }$ temperature.

(e)

Using the data in the graphs, discuss whether species in Group 1 or Group 2 are more likely to be adversely affected by increases in soil temperature due to global warming.

[ 2 ]

a. group 1 because there is less gap between $\mathrm{T}_{\text {opt }}$ and $\mathrm{T}_{\text {max }}$
OR
group 1 is more likely to be adversely affected by increase in soil temperature because they have a narrow range of tolerance for higher temperatures than in group 2;
b. group 1 because $\mathrm{T}_{\max }$ is lower in most species;
c. if global warming heats up the soil temperature, the seeds will germinate earlier which may be adverse (in either group);
d. group 2 because $\mathrm{T}_{\text {opt }}$ is (generally) lower (than group 1);
e. however, some species in group 2 have as low a $\mathrm{T}_{\max }$ as group 1, therefore some species in group 2 will be adversely affected;
f. species (regardless of group) may be adversely affected because increasing soil temperature means less water available for germination;

[Maximum number: 1]

Reef-building corals are an association between two organisms: coral polyps and Zooxanthellae.

Coral-polyp section labelled Tentacle, Mouth and Pharynx above a shaded calcium-carbonate skeleton labelled CaCO₃ skeleton.

State one limiting factor on Zooxanthellae which affects coral reef formation.

[Maximum number: 5]

The climograph shows the distribution of biomes according to the temperature and rainfall of land areas on Earth.

Mean annual temperature / $^{\circ}\mathrm{C}$

(a)

Identify the ecosystem with the appropriate numeral from the climograph.

[ 2 ]

Ecosystem	Numeral
Tropical rainforest	IV
Desert	II
Tundra	I

(b)

Referring to the climograph, explain reasons that the nutrient store in the litter layer of the taiga is greater than in the tropical rainforest.

[ 3 ]

[Maximum number: 3]

Outline characteristics of a named biome.

[Maximum number: 7]

Convergent evolution increases similarities, despite differences in origins.

Describe adaptations that are typical of plants growing in hot deserts throughout the world.

All question bank results loaded

Covered syllabus points

Question 1

Question (a)

Question (b)

Question 2

Question 3

Question 4

Question 5

Question (a)

Question (b)

Question (c)

Question (d)

Question (e)

Question 6

Question 7

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Question (b)

Question 8

Question 9