[Campbell Biology P.914] A plant adapted to temperate climates is suddenly exposed to a seve... | Practice Question

A plant adapted to temperate climates is suddenly exposed to a severe, rapid drop in temperature below 0°C. Based on the text, what is the most direct consequence to its cells if they do not possess specific freezing tolerance mechanisms like those mentioned?

  • A: Increased cytoplasmic water potential, leading to cell swelling and lysis.
  • B: Formation of ice crystals in the cytosol, directly denaturing enzymes.
  • C: Water leaving the cytoplasm due to reduced extracellular water potential, leading to increased intracellular ion concentration and cell death.
  • D: Rapid synthesis of heat-shock proteins, which are ineffective against cold-induced damage.

Explanation

The 'Freezing' section explains that 'ice forms in the cell walls and intercellular spaces of most plants.' This 'lowers the extracellular water potential, causing water to leave the cytoplasm. The resulting increase in the concentration of ions in the cytoplasm is harmful and can lead to cell death.'