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

What does gene switching allow within specialized cells?

1. All genes to be active at all times

2. The ability to switch on needed genes and switch off unneeded ones

3. Continuous production of all proteins

4. The random activation of genes

The correct answer is: The ability to switch on needed genes and switch off unneeded ones

Gene switching plays a crucial role in the functioning of specialized cells by allowing them to activate specific genes that are necessary for their unique functions while simultaneously repressing genes that are not needed. This selective activation and suppression is essential for cellular differentiation, enabling cells to perform distinct roles in the body. For example, a muscle cell will express genes that are relevant for muscle contraction but will not activate genes that are involved in other cell types' functions, such as those in nerve or blood cells. The ability to control which genes are expressed at any given time is fundamental for maintaining the identity and functionality of different cell types. This mechanism ensures that cells adapt to their environment and meet their functional requirements efficiently. In contrast, the other choices do not accurately describe the process of gene switching. Continuous activation of all genes would lead to unregulated cell activity and could result in cellular dysfunction. The random activation of genes does not reflect the precise regulation necessary for specialization. Hence, the correct understanding of gene switching is evident through the ability to turn on necessary genes while turning off those that are unneeded.