OCR Gateway GCSE Biology A: Organism level systems (B3) overview
An overview of the organism level systems content (topic B3) in OCR Gateway GCSE Biology A (J247), mapping the nervous system, the brain and the eye, the endocrine system, control of blood glucose, hormones in reproduction and plant hormones, and how they are examined on the first biology paper.
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The third biology topic of OCR Gateway GCSE Biology A (specification J247) is about coordination and control: how organisms detect changes and respond. B3 Organism level systems is examined on the first biology paper (J247/01 at Foundation, J247/03 at Higher). This page maps the topic and links to a focused answer page for each part.
The organism level systems content
- The nervous system
- The central nervous system, the three neurones, synapses, the reflex arc and reaction time. See The nervous system.
- The brain and the eye (Higher)
- The cerebral cortex, cerebellum and medulla, the structure of the eye, accommodation and the iris reflex. See The brain and the eye.
- The endocrine system
- Glands and hormones, target organs and receptors, the main endocrine glands, and nervous versus hormonal control. See The endocrine system.
- Control of blood glucose
- Insulin and glucagon, the pancreas and liver, negative feedback, and type 1 and type 2 diabetes. See Control of blood glucose.
- Hormones in reproduction
- FSH, LH, oestrogen and progesterone, the menstrual cycle, contraception and fertility treatments including IVF. See Hormones in reproduction.
- Plant hormones
- Auxins, phototropism and gravitropism, and the commercial uses of plant hormones. See Plant hormones.
How this topic is examined
Topics B1 to B3 are assessed on the first biology paper, which is 1 hour 45 minutes, worth 90 marks and 50% of the GCSE. Questions include multiple choice, short structured answers, data and graph interpretation (blood glucose, hormone levels) and six-mark extended responses such as the menstrual cycle or a reflex arc. Every paper also tests B7 practical skills, so the reaction time practical can be examined here.
How to study the organism level systems topic
- Work from the specification statements. Each point is a checklist; questions are written from them.
- Learn the sequences. The reflex arc order and the menstrual cycle hormones are marked on the correct order.
- Learn the hormone pairs. Insulin lowers and glucagon raises blood glucose; FSH matures the egg and LH triggers ovulation.
- Master the Higher content. The brain regions and accommodation appear on Higher tier papers.
- Practise the reaction time practical. Know the method, the controls and how to find a mean.
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.