OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

What is the purpose of forming polymers like starch in plant cells?

1. To enhance water flow through the plant

2. To store excess glucose for energy

3. To protect against pests

4. To provide structural support

The correct answer is: To store excess glucose for energy

The formation of polymers like starch in plant cells primarily serves the function of storing excess glucose for energy. Plants produce glucose during photosynthesis, and when there is more glucose than the plant immediately needs for energy or growth, it converts this excess glucose into starch. Starch is a polysaccharide that acts as a compact energy reserve, which can be broken down back into glucose molecules when the plant requires energy, such as during periods of low photosynthesis (like at night or during winter). Starch is particularly advantageous because it allows plants to store energy in a stable form, which can be mobilized when necessary, ensuring a consistent energy supply to support growth and metabolic processes. This storage strategy is crucial for plant survival, especially since they cannot move to find food like animals can. Therefore, the primary purpose of forming starch as a polymer is to create a means for efficient energy storage that can sustain the plant over time.