AQA GCSE Biology Paper 1 Practice Exam 2026 - Free GCSE Biology Practice Questions and Revision Guide

Using paraffin heaters in greenhouses provides the significant benefit of increasing carbon dioxide concentration within the environment. When paraffin is burned, it produces carbon dioxide as a byproduct. This increase in carbon dioxide concentration is beneficial for plants because carbon dioxide is a key ingredient in photosynthesis, the process by which plants convert light energy into chemical energy, producing glucose and oxygen. Higher levels of carbon dioxide can lead to improved plant growth and yield, as plants become more efficient in photosynthesis when more of this gas is available.

In contrast, while increasing temperature may also be a desirable effect of heating, the primary unique advantage of paraffin heaters is their contribution to carbon dioxide concentration. The other options—reducing water loss from plants and enhancing light penetration—do not directly relate to the operation of paraffin heaters and their primary function, which is to provide heat and an increase in carbon dioxide levels.