Certified Professional Horticulturist (CPH) Practice Exam

What term describes rapid freezing and formation of ice crystals within plant cells?

1. Extracellular ice formation

2. Supercooling

3. Desiccation injury

4. Intracellular ice formation

The correct answer is: Intracellular ice formation

Intracellular ice formation refers to the process where ice crystals form within the cells of a plant. This phenomenon can severely damage the plant's cellular structure and function. When temperatures drop rapidly, water within the cells can freeze, forming ice crystals that can puncture cellular membranes and disrupt the integrity of organelles. This internal damage often leads to cell death and can significantly impact the plant's overall health and survival. Understanding this process is crucial, especially in horticulture, where managing plant stress and resilience to cold temperatures is essential. In contrast, other terms like extracellular ice formation pertain to ice forming outside the cells, and supercooling describes a state where water remains liquid below its normal freezing point without forming ice, both of which relate to different aspects of plant response to freezing. Desiccation injury involves damage due to dehydration rather than freezing, illustrating more about water loss than the effects of ice formation within cells.