OCR Gateway GCSE Combined Science A Biology: cells and transport (B1 to B2) overview
An overview of the cell level systems and scaling up content (topics B1 and B2) in OCR Gateway GCSE Combined Science A (J250), mapping cell structure, enzymes, respiration, photosynthesis, mitosis, transport across membranes and transport systems, and how they are examined on Biology Paper 1.
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The first two biology topics of OCR Gateway GCSE Combined Science A (specification J250) build from the single cell up to whole-organism transport. B1 Cell level systems and B2 Scaling up are examined on Biology Paper 1. This page maps the topics and links to a focused answer page for each.
The cells and transport topics
- Cell level systems (B1)
- Eukaryotic and prokaryotic cells, the function of each sub-cellular structure, light and electron microscopy, the magnification equation, and using standard form for cell sizes. See Cell level systems.
- Enzymes and metabolism (B1)
- Enzymes as biological catalysts, the lock and key model, the effects of temperature, pH and substrate concentration, denaturing, and the digestive enzymes. See Enzymes and metabolism.
- Photosynthesis and respiration (B1)
- Aerobic and anaerobic respiration, photosynthesis as an endothermic reaction, limiting factors, and the inverse square law for light intensity. See Photosynthesis and respiration.
- Cell division and mitosis (B2)
- The cell cycle, mitosis producing genetically identical cells, growth, repair and asexual reproduction, and stem cells in embryos, adults and plant meristems. See Cell division and mitosis.
- Transport in and out of cells (B2)
- Diffusion, osmosis and active transport, the factors affecting diffusion rate, surface area to volume ratio, and adaptations of exchange surfaces. See Transport in and out of cells.
- Transport systems (B2)
- The heart and double circulation, arteries, veins and capillaries, the components of blood, and transport in plants by xylem and phloem. See Transport systems.
How these topics are examined
Topics B1 to B3 are assessed on Biology Paper 1, which is 1 hour 10 minutes, worth 60 marks and one sixth of the overall Combined Science grade. Questions include multiple choice, short structured answers, calculations (magnification, rates, surface area to volume ratio) and six-mark extended responses. Every paper also tests CS7 practical skills, so the osmosis, microscopy, enzyme and photosynthesis practicals can be examined here.
How to study the cells and transport topics
- Work from the specification statements. Each point is a checklist; questions are written from them.
- Learn definitions exactly. Diffusion, osmosis, active transport and denaturing are marked on precise wording.
- Drill the maths. Magnification, rate of reaction and surface area to volume ratio appear repeatedly.
- Master the practicals. Microscopy, osmosis in potato, enzyme activity and the effect of light on photosynthesis recur in the exams.
- Practise six-mark questions. Extended responses on limiting factors, transpiration and the heart reward a logical, well-linked argument.
For the official specification
OCR publishes the full specification, past papers and mark schemes at ocr.org.uk. Always revise from the current specification and OCR's own past papers, because question style is board-specific.