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IB Biology HL B4.1 Adaptation to Environment Questions

Practise IB Biology HL B4.1 by interpreting distribution and tolerance data, comparing biomes, and explaining desert, rainforest, saline and waterlogged adaptations.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Explain how xerophyte leaves and roots and hot-desert plants reduce water loss through waxy cuticles, reduced leaves, deep roots or water storage.
  • Relate desert-animal behaviour, kidney function and nitrogenous-waste choice to conserving water and avoiding heat.
  • Explain how saline or waterlogged plants use ion handling, salt excretion and aerial roots or pneumatophores for salt balance and gas exchange.
  • Identify abiotic factors and interpret temperature or light gradients to relate limiting conditions to growth, productivity or species distribution.
  • Interpret tolerance-range data to identify optimum, stress and intolerance zones, and assess evidence that pH limits a species’ range.
  • Interpret coral-cover data and explain how ocean warming and carbon-dioxide-driven acidification constrain coral abundance and reef construction.
  • Identify a terrestrial biome from a climograph using its temperature and precipitation pattern.
  • Relate seasonal temperature, light and nutrient cycling to leaf-area index, litter stores and biome productivity.
  • Distinguish the biosphere from a biome and compare named biomes by climate, moisture and vegetation, including tundra.
  • Explain how tropical-rainforest pitcher plants capture and digest insects to obtain mineral nutrients from nutrient-poor soils.

Covered syllabus points

B4.1.1—Habitat definitionB4.1.2—Adaptations to abiotic environmentB4.1.3—Abiotic variables affecting distributionB4.1.4—Range of tolerance of limiting factorB4.1.5—Coral reef formation conditionsB4.1.6—Terrestrial biome distributionB4.1.7—BiomesB4.1.8—Adaptations to hot deserts and tropical rainforest

Question 1

[Maximum number: 2]

The diagram shows a nephron from a mammal.

Figure for Question 1 — IB Biology HL

Outline two adaptations for water conservation in leaves of desert plants.

Question 2

[Maximum number: 4]

The model describes the fundamental and realized niches of a species of microscopic marine arthropod in the Northern hemisphere with respect to two different factors ( X and Y ). The abundance of the species is shown over twelve months. The fundamental niche is separated into five zones ranging from critical to optimal conditions. The population of the species in its realized niche each month is represented by an oval. The size of each oval shows the population abundance.

Figure for Question 2 — IB Biology HL

Question (a)

(a)

Outline how factor Y affects the species from January to April.

[ 2 ]

Question (b)

(b)

Suggest, with a reason, what factor Y could be.

[ 2 ]

Question 3

[Maximum number: 3]

Coral reefs are among the most spectacular ecosystems on Earth. They support a rich diversity of life and provide economic benefits to the people who use them. In Papua New Guinea in the Pacific Ocean north of Australia the following data were collected. Coral cover is the percentage of the reef surface covered by live hard coral.

Dual-axis line graph for 1994–2004: dashed line gives live coral cover on the left percentage axis, 0–80%; grey solid line gives mean annual ocean temperature on the right axis, 24.30–24.70°C.

Question (a)

(a)

Calculate the difference in coral cover in 1996 and 2002. No working required.
……%

[ 1 ]

Question (b)

(b)

Describe the evidence that the ocean temperature has an effect on coral cover.

[ 2 ]

Question 4

[Maximum number: 2]

The model describes the fundamental and realized niches of a species of microscopic marine arthropod in the Northern hemisphere with respect to two different factors ( X and Y ). The abundance of the species is shown over twelve months. The fundamental niche is separated into five zones ranging from critical to optimal conditions. The population of the species in its realized niche each month is represented by an oval. The size of each oval shows the population abundance.

Figure for Question 4 — IB Biology HL

Suggest, with a reason, what factor Y could be.

Question 5

[Maximum number: 2]

The model describes the fundamental and realized niches of a species of microscopic marine arthropod in the Northern hemisphere with respect to two different factors ( X and Y ). The abundance of the species is shown over twelve months. The fundamental niche is separated into five zones ranging from critical to optimal conditions. The population of the species in its realized niche each month is represented by an oval. The size of each oval shows the population abundance.

Figure for Question 5 — IB Biology HL

Outline how factor Y affects the species from January to April.

Question 6

[Maximum number: 3]

Remote sensing satellites are used to monitor the Earth's ecosystems. One measure of ecosystem status is leaf area index (LAI), which is the total area of leaves in square metres per square metre ( m2 m−2\mathrm{m}^{2} \mathrm{~m}^{-2} ) of the Earth's surface. The graph shows LAI estimates, calculated using data from the Global Inventory Monitoring and Modelling System (GIMMS), during the period from 1981 to 2011. The data points are monthly averages in four latitudinal zones in the northern hemisphere.

Figure for Question 6 — IB Biology HL

Suggest reasons for the differences in LAI between the boreal and equatorial zones.

Figure for Question 6 — IB Biology HL

Question 7

[Maximum number: 2]

The photo shows vegetation in the Sonoran Desert, which is part of the hot desert biome.

Figure for Question 7 — IB Biology HL

State what a biome is.

Question 8

[Maximum number: 3]

The photo shows vegetation in the Sonoran Desert, which is part of the hot desert biome.

Figure for Question 8 — IB Biology HL

Explain three adaptations of plants that can help them survive in the dry conditions of hot deserts.

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