Key term
OCR GCSE Combined Science Biology J250
Cell Level Systems
Topic overviewMicroscopy, and sub-cellular structuresDNA structure: polymer, double helix and nucleotidesEnzyme action, and investigating enzymesCellular respiration as an exothermic processAerobic and anaerobic respiration comparedSynthesis and breakdown of carbohydrates, proteins and lipidsPhotosynthesis: producers and the processPhotosynthesis as endothermic, and investigating itLimiting factors in photosynthesis
Community Level Systems
Genes, Inheritance and Selection
Topic overviewGenetic terms, and the genomeGenome, environment and mutationsHaploid, diploid and meiosisSingle gene inheritance and Punnett squaresSex determination and characteristics controlled by many genesVariation within a population, and classificationNatural selection and evolutionEvidence for evolution from fossils and antibiotic resistance
Global Challenges
Topic overviewField investigations, and human impact on ecosystemsMaintaining biodiversity, monitoring conservation and ecotourismSelective breeding and genetic engineeringHealth, disease, and types of diseaseInteractions between diseases, and how they spreadReducing the spread of disease, and named examplesWhite blood cells, antibodies and plateletsNon-specific defences and the immune systemVaccines, medicines and aseptic techniqueDeveloping new medicines, and non-communicable diseaseTreating cardiovascular disease, and lifestyle factorsCancer, and the use of stem cells in medicineGene technology in medicine, and the human genome
Organism Level Systems
Scaling Up
Topic overviewDiffusion, osmosis and active transportMitosis, the cell cycle and cell differentiationStem cells in animals and meristems in plantsSurface area to volume ratio and exchange surfacesThe circulatory system, the heart and blood vesselsRed blood cells and plasmaRoot hair cells, transpiration and translocationXylem and phloemFactors affecting water uptake, and the potometer
Organism Level Systems
- 8 subtopics
- 24 things to know
- Paper 1 (Biology)
What Organism Level Systems covers
Organism Level Systems is examined in Paper 1 (Biology). It covers the nervous system and coordinated responses; the reflex arc; hormones, endocrine glands and hormonal coordination; hormones in reproduction and the menstrual cycle; contraception; homeostasis and control systems in the body; insulin in blood sugar control; and type 1 and type 2 diabetes.
Where it is assessed
Paper 1 (Biology)
Combined Science A, Paper 1 (Biology): 1 hour 10 minutes, 60 marks, 16.7% of the qualification.
Check the OCR specification ↗The 8 subtopics
Each one has its own page.
- The nervous system and coordinated responsesThe central nervous system, what sensory, motor and relay neurones, receptors and effectors do, how sensory and motor neurones differ in shape, synapses and neurotransmitters, what a coordinated response is and why many receptors and connections help, the stages from stimulus to response, catching a falling glass, and why nervous responses are faster than hormonal ones.Open →
- The reflex arcWhat a reflex action is and why it protects the body, the parts of a reflex arc in order, why a reflex is faster than a voluntary action, the relay neurone in the spinal cord, how synapses slow an impulse, the hot pan and blinking reflexes, why a person is aware of a reflex, and why the same stimulus always gives the same response.Open →
- Hormones and the endocrine glandsWhat a hormone and an endocrine gland are, how hormones travel in the blood yet affect only some organs, the main endocrine glands including the adrenal glands, the hormones of the ovaries and testes, and how hormonal and nervous responses compare.Open →
- Hormones in reproduction and the menstrual cycleTestosterone and oestrogen and what each does at puberty, what FSH does and where it is released from, the role of progesterone, the length of the menstrual cycle and when an egg is released, and what happens to the uterus lining without fertilisation.Open →
- Methods of contraceptionHow the combined pill, other hormonal methods, condoms and other barrier methods prevent pregnancy, the advantages and disadvantages of each, sterilisation, why natural methods are less reliable, and which methods are the most effective.Open →
- Homeostasis and control systems in the bodyWhat homeostasis is, the conditions held constant inside the body, why body temperature stays close to 37 °C, the three parts of a control system, how the body corrects a change in temperature, and why the water content of the blood is controlled.Open →
- Insulin and the control of blood glucoseWhich organ monitors blood glucose, how insulin makes body cells take up glucose, storing it as glycogen in the liver and muscles, why blood glucose falls after a meal and must be controlled, and insulin control as negative feedback.Open →
- Type 1 and type 2 diabetesWhat type 1 and type 2 diabetes are, when each usually appears, insulin injections and why insulin cannot be swallowed, diet and exercise for type 2, risk factors, symptoms, and glucose in the urine.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
A person's body temperature rises above normal and then returns to normal. Explain how this shows the body correcting a change.
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Give an external change and an internal change that the body must respond to in order to keep conditions constant.
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Explain why blood glucose falls in the hour after a large meal.
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Which two organs make up the central nervous system?
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What is a reflex action?
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What is a hormone?
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Which is the main male reproductive hormone and where is it made?
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What is type 1 diabetes?
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What is a sensory receptor?
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Name the parts of a reflex arc in the order an impulse passes through them.
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What is an endocrine gland?
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Which is the main female reproductive hormone and where is it made?
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Name three hormonal methods of contraception other than the pill.
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Which hormone is released when the blood glucose concentration is too high, and from where?
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What is type 2 diabetes?
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What is an effector?
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Where is the relay neurone of a spinal reflex arc found, and why does this matter?
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A hormone reaches every organ, so why does it affect only some of them?
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What does FSH do, and where is it released from?
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Which methods of contraception are the most effective, and how do condoms compare?
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What is homeostasis?
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What sort of molecule is glycogen and where is it stored?
Process
At what stage of life does each type of diabetes usually first appear?
Take Organism Level Systems further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Insulin vs Glucagon
Insulin: pancreatic hormone that makes cells take up glucose and store it as glycogen. Glucagon: pancreatic hormone that makes the liver turn glycogen back into glucose.
Questions from this topic
Each one with the model answer underneath.
- 1
Which two organs make up the central nervous system?
Model answer
The brain and the spinal cord.
- 2
What is the job of a sensory neurone?
Model answer
It carries electrical impulses from a sensory receptor to the central nervous system.
- 3
What is the job of a motor neurone?
Model answer
It carries electrical impulses from the central nervous system to an effector.
- 4
Where are relay neurones found and what do they do?
Model answer
They lie inside the central nervous system and pass impulses from sensory neurones on to motor neurones.
- 5
What is a sensory receptor?
Model answer
A cell that detects a stimulus such as light, sound, touch, temperature or a chemical, and starts an electrical impulse.
- 6
What is an effector?
Model answer
A muscle or a gland that carries out the response when an impulse arrives from a motor neurone.
What is inside Levo
Six ways to work the same material.
Organism Level Systems revision questions
- What does Organism Level Systems cover in OCR GCSE Combined Science Biology?
- 8 subtopics: the nervous system and coordinated responses, the reflex arc, hormones and the endocrine glands, hormones in reproduction and the menstrual cycle, methods of contraception, homeostasis and control systems in the body, insulin and the control of blood glucose and type 1 and type 2 diabetes. Each one has its own page with questions and model answers.
- How is Organism Level Systems organised?
- By the OCR J250 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Organism Level Systems, on a schedule.
Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.
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