A Level Biology Practice Exam

In plant physiology, what do "sinks" refer to?

1. Regions responsible for photosynthesis

2. Regions that store excess nutrients

3. Regions requiring assimilates for metabolic needs

4. Regions for gas exchange

The correct answer is: Regions requiring assimilates for metabolic needs

In plant physiology, "sinks" refer specifically to regions within the plant that require assimilates, such as sugars and nutrients, to support their metabolic needs. These areas can include growing tissues like roots, fruits, seeds, and young leaves. As plants carry out photosynthesis in their leaves, they produce glucose and other carbohydrates, which are then transported to these sink regions where they are utilized for growth, energy, and development. This movement and allocation are essential for the plant's overall health and functioning, especially during periods of growth or reproduction. The other contexts mentioned in the question highlight different functions but do not align with the definition of sinks. Regions that are responsible for photosynthesis focus on the production process rather than the consumption of assimilates. Areas that store excess nutrients pertain to storage functions rather than metabolic utilization. Regions for gas exchange are associated with the exchange of oxygen and carbon dioxide, which while important for overall plant function, do not directly relate to the concept of sinks in plant physiology.