All cells need energy to survive. They obtain this energy by carrying out a series of chemical reactions that are collectively known as respiration.

The development of microscopes, particularly the electron microscope, has helped scientists to learn more about how cells function.

Multicellular organisms grow by increasing the number of cells they have. This relies on the processes of cell division and differentiation.

Gain an in-depth understanding of mitosis with this guide and interactive activity from BBC Bitesize, written to the GCSE OCR 21st Century biology specification.

Plants release hormones that are vital for their correct growth and development. This helps them to respond to their environment.

Understanding how to approach exam questions helps to boost exam performance. Question types will include multiple choice, structured, mathematical and practical questions.