Examkin

Question

Difficulty: HardBiomes and Aquatic/Terrestrial Habitats

In the Taiga (boreal forest) biome, despite the presence of snow and ice during long winter months, dominant coniferous trees exhibit xeromorphic adaptations such as needle-shaped leaves, heavy cutinization, and sunken stomata. Which environmental factor primarily accounts for the necessity of these drought-resisting features in this biome?

  1. Physiological drought caused by frozen soil water that prevents root absorption during freezing temperaturesAnswer
  2. B
    High rates of transpiration induced by intense solar radiation and high ambient temperatures throughout the winter
  3. C
    Excessive soil salinity resulting from high evaporation rates during short summer months
  4. D
    Degradation of xylem vessels caused by extracellular saprophytic bacterial activity in acidic waterlogged soils

Answer

Physiological drought caused by frozen soil water that prevents root absorption during freezing temperatures
In the Taiga biome, winter temperatures remain below freezing for extended periods. Water in the soil turns into ice, making it physically impossible for root cells to absorb liquid water via osmosis. This state of unavailable water is termed physiological drought. Coniferous trees rely on xeromorphic leaf adaptations (such as needle shape, thick waxy cuticle, and sunken stomata) to minimize water loss through transpiration while root absorption is completely suspended.

Step-by-Step Solution

1
Analyze the environmental conditions of the Taiga biome during winter
Sub-zero winter temperatures cause water in the soil and subsoil to freeze into ice.
Determining the physical state of soil water is essential to assess its availability for plant uptake.
2
Determine the physiological consequence of frozen soil water on root transport
Plant roots cannot transport frozen water, creating a condition known as physiological drought.
Osmotic absorption and transpiration pull require liquid water to function across root membranes.
3
Correlate structural plant modifications with physiological drought
Needle leaves, reduced surface area, thick cuticles, and sunken stomata minimize cuticular and stomatal water loss while uptake is halted.
Xeromorphic features allow conifers to conserve internal water reserves until soil water thaws.

Key Concept

Physiological drought and xeromorphic adaptations in cold biomes
Rate this question

Topics

Biomes and Aquatic/Terrestrial Habitats

More questions from this topic