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

What do cells engaging in active transport typically contain?

1. Large amounts of chloroplasts

2. High levels of cellulose

3. Large numbers of mitochondria

4. Extensive amounts of cytoplasm

The correct answer is: Large numbers of mitochondria

Cells that engage in active transport typically contain large numbers of mitochondria. Active transport is a process that requires energy to move substances against their concentration gradient. This energy is generated through cellular respiration, which occurs in the mitochondria. The more active transport a cell performs, the greater its demand for ATP (adenosine triphosphate), the energy currency of the cell. Therefore, high numbers of mitochondria provide the necessary ATP to support the energy-intensive process of moving molecules across cell membranes. The other options focus on features that are less relevant to the process of active transport. For instance, chloroplasts are involved in photosynthesis, which is primarily a function of plant cells, while cellulose is a structural component of plant cell walls rather than a direct participant in transport processes. Extensive amounts of cytoplasm may be present in many cell types, but it does not specifically relate to the energy demands of active transport.