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

How does the cell membrane contribute to anaerobic respiration?

1. It synthesizes glucose

2. It allows water and gases to pass freely in and out of the cell

3. It stores proteins

4. It produces energy

The correct answer is: It allows water and gases to pass freely in and out of the cell

The cell membrane plays a crucial role in anaerobic respiration by allowing the movement of water and gases in and out of the cell. During anaerobic respiration, which occurs in the absence of oxygen, cells must rely on alternative pathways to produce energy. This process leads to the production of byproducts such as carbon dioxide or ethanol, depending on the organism. The cell membrane's selective permeability ensures that essential substrates, like glucose, can enter the cell to fuel the anaerobic respiration process. At the same time, it enables the removal of byproducts, which is vital for maintaining the cell's internal environment and optimizing metabolic processes. This exchange is vital as it helps to regulate osmotic balance and ensure that metabolic pathways can proceed efficiently even when oxygen is limited. While the other options suggest processes associated with cellular function, they do not directly pertain to the specific role of the cell membrane in facilitating anaerobic respiration. For instance, glucose synthesis is a separate metabolic pathway often occurring in the chloroplasts of plant cells or through gluconeogenesis in liver cells. Storage of proteins is related to cellular structure and function, rather than directly linked to anaerobic respiration. Although energy production is a primary goal of anaerobic respiration, the membrane’s role is more about enabling