Edexcel GCSE Biology Topic 2 Cells and control: a complete overview of mitosis, growth, stem cells, the nervous system, the brain and the eye
A deep-dive Edexcel GCSE Biology guide to Topic 2 Cells and control. Covers mitosis and the cell cycle, cancer, growth and percentile charts, differentiation and stem cells, neurones and the reflex arc, and (Biology only) the brain, brain scans and the eye, with the exam patterns Edexcel repeats.
Reviewed by: AI editorial process; not yet individually human-reviewed
Jump to a section
What Topic 2 actually demands
Cells and control builds on Topic 1 by looking at how cells divide, grow, specialise and coordinate the body. The examiners test precise sequences (the cell cycle, the reflex arc), the contrast between mitosis and meiosis, and the structure-to-function logic of the nervous system and (Biology only) the eye. This guide ties together the four dot-point pages, each with its own practice questions.
Mitosis, growth and stem cells
The cell cycle has a long growth stage (interphase), in which the cell grows and copies its DNA, followed by mitosis (prophase, metaphase, anaphase, telophase) and cytokinesis. Mitosis produces two genetically identical daughter cells and is used for growth, repair and asexual reproduction. When the cell cycle loses control through mutations, the result is cancer, a tumour of uncontrolled cell division.
Organisms grow by cell division and differentiation; plants also grow by cell elongation at meristems. Percentile charts monitor growth over time. Stem cells are undifferentiated: embryonic stem cells form any cell type, adult stem cells a limited range, and meristems divide for life. Their medical promise (treating diabetes, paralysis) is balanced against rejection, infection and ethical concerns.
The nervous system
The nervous system carries information as electrical impulses along neurones: sensory (receptor to CNS), relay (within the CNS) and motor (CNS to effector). At a synapse, the impulse triggers neurotransmitter chemicals that diffuse across the gap to start a new impulse. A reflex arc (receptor, sensory neurone, relay neurone, motor neurone, effector) gives a fast, automatic, protective response by bypassing the conscious brain.
The brain and the eye (Biology only)
The brain has named regions: the cerebral hemispheres (thinking, memory, senses), the cerebellum (movement and balance) and the medulla (heart rate and breathing). CT and PET scans study its structure and activity. The eye focuses light on the retina by changing the lens shape (accommodation). Short sight (eyeball too long) needs a concave lens; long sight (eyeball too short) a convex lens; cataracts are cloudy lenses replaced surgically.
How Topic 2 is examined
- Sequences. The stages of mitosis and the steps of the reflex arc, in order.
- Comparisons. Mitosis versus meiosis, embryonic versus adult stem cells, short sight versus long sight.
- Structure to function. How neurones and the eye are adapted to their jobs.
- Data. Reading percentile charts and interpreting growth.
Check your knowledge
A mix of recall and application questions covering Topic 2. Attempt them under timed conditions, then check against the solutions.
- Name the stage of the cell cycle in which the DNA is copied. (1 mark)
- State how many daughter cells mitosis produces and how their chromosomes compare with the parent. (2 marks)
- Give one way growth in plants differs from growth in animals. (1 mark)
- State one benefit and one risk of using stem cells in medicine. (2 marks)
- Put the parts of the reflex arc in the correct order. (2 marks)
- Explain why a reflex action is fast. (2 marks)
- State the function of the cerebellum. (1 mark)
- A person's eyeball is too short. Name the defect and the lens used to correct it. (2 marks)
Sources & how we know this
- Pearson Edexcel GCSE (9-1) Biology (1BI0) specification — Pearson (2016)