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
Topic overviewThe nervous system and coordinated responsesThe reflex arcHormonal coordination, thyroxine and adrenalineHormones in reproduction and the menstrual cycleContraception and treating infertilityHomeostasis and control systems in the bodyInsulin and glucagon in blood sugar controlType 1 and type 2 diabetes
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
Insulin and glucagon in blood sugar control
- 3 things to know
- Paper 7 (Biology)
Overview
The pancreas monitoring blood glucose, how insulin makes cells take up glucose and the liver and muscles store it as glycogen, why blood glucose must be controlled, negative feedback, how glucagon releases glucose from glycogen, insulin and glucagon as antagonistic hormones, what happens after a meal, between meals and during a long run, and the part the liver plays.
What you need to know
Answer each one before you reveal it.
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Key term
Explain how insulin and glucagon work together to hold blood glucose steady.
Key term
Which hormone is released when the blood glucose concentration is too high, and from where?
Questions from this subtopic
Each one with the model answer underneath.
- 1
Which organ monitors the concentration of glucose in the blood?
Model answer
The pancreas.
- 2
Which hormone is released when the blood glucose concentration is too high, and from where?
Model answer
Insulin, released from the pancreas.
- 3
What effect does insulin have on the body cells?
Model answer
It makes them take glucose out of the blood and into the cell.
- 4
What happens to the glucose taken up by the liver and muscles under the action of insulin?
Model answer
It is converted into glycogen and stored.
- 5
Explain why blood glucose falls in the hour after a large meal.
Model answer
The rise in glucose makes the pancreas release insulin, which causes cells to take up glucose and the liver and muscles to store it as glycogen, so less glucose is left in the blood.
- 6
What sort of molecule is glycogen and where is it stored?
Model answer
A large carbohydrate made of many glucose molecules joined together, stored in the liver and in the muscles.
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