IB Biology HL B4.1 Adaptation to environment 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.

Question 1

Multiple choiceMedium1 mark

Two regions on separate continents have the climate patterns shown. What is likely about their biomes and communities?

RegionTemperature through the yearRainfall through the year
PConsistently highConsistently high
QConsistently highConsistently high
Show answer and explanation

Answer: A. Biome distribution is associated with patterns of temperature and rainfall. Consistently high values for both are characteristic of tropical forests; similar abiotic conditions can favor similar communities through convergent evolution.
B: selects hot desert from the high temperature but overlooks the consistently high rainfall.
C: classifies rainfall as biotic; it is an abiotic factor that helps determine biome distribution.
D: matches the high rainfall but overlooks the consistently high temperature.
Remember: terrestrial biome distribution reflects both temperature and precipitation.

Question 2

Paper 2Hard16 marks

At Kestrel Bay, marram grass (Ammophila arenaria) grows on exposed foredunes above the high-tide line, where the sand is dry and shifting and winds are strong. Grey mangrove trees (Avicennia marina) grow in the lower intertidal estuary, in a mangrove swamp with waterlogged sediment. Marram leaves roll inward during dry, windy periods; the stomata are on the inner surface of the rolled leaves. Grey mangroves have aerial roots that project above the sediment and have openings exposed to the air.

Table 1. Conditions measured in the two habitats

HabitatSoil water content (%)Pore-water salinity (g kg⁻¹)Soil oxygen (%)
Foredune6218
Mangrove swamp68253

To estimate the number of grey mangrove trees in a 0.80 ha area of swamp, six non-overlapping 100 m² quadrats were selected at random. The numbers of trees counted were:

Quadrat123456
Trees counted81191079

Seedlings of both species were also grown for eight weeks under two substrate conditions. The “dune-like” and “swamp-like” treatments reproduced the corresponding moisture, salinity and soil oxygen conditions in Table 1. Light, temperature and nutrient availability were kept constant. Each value is the mean dry-mass increase per seedling for 10 seedlings.

Table 2. Mean dry-mass increase after eight weeks

SpeciesDune-like substrate (g)Swamp-like substrate (g)
Marram grass2.40.5
Grey mangrove0.72.2
(a)

Describe the habitat of each species, including its physical location and ecosystem type.

[2]
(b)

Calculate the estimated number of grey mangrove trees in the 0.80 ha area.

[3]
(c)

Explain how the stated leaf feature of marram grass and root feature of grey mangrove help each species survive in its habitat.

[6]
(d)

An ecologist concludes that each species is adapted to the abiotic conditions of its own habitat and that matching the three soil conditions in Table 1 is sufficient to ensure successful long-term establishment after transplantation. Evaluate this conclusion using the data and the study context.

[5]

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