Key term
OCR GCSE Biology A J247
Cell Level Systems
Topic overviewMicroscopy, and sub-cellular structuresDNA structure: polymer, double helix and nucleotidesProtein synthesis and the triplet codeEnzyme 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 mutationsHow genetic variants influence phenotypeAsexual and sexual reproduction comparedHaploid, diploid and meiosisSingle gene inheritance and Punnett squaresSex determination, multiple genes and Mendel's workVariation within a population, and classificationNatural selection and evolutionEvidence for evolution, and the work of Darwin and Wallace
Global Challenges
Topic overviewField investigations, and human impact on ecosystemsMaintaining biodiversity, and evidence for environmental changeFood security, agricultural and biotechnological solutionsSelective breeding and genetic engineeringHealth, disease, and types of diseaseInteractions between diseases, and how they spreadReducing the spread of disease, and named examplesPhysical and chemical plant defencesDetecting plant disease; white blood cells and plateletsNon-specific defences and the immune systemMonoclonal antibodies and their usesVaccines, 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 arcThe eye and its common defectsThe structure and function of the brainInvestigating and treating the brainHormonal coordination, thyroxine and adrenalineHormones in reproduction and the menstrual cycleContraception and treating infertilityPlant hormones and their commercial usesHomeostasis, and the skin in temperature controlInsulin and glucagon in blood sugar controlType 1 and type 2 diabetesOsmotic changes in body fluids, and the kidneysThe kidney tubule and the effect of ADHResponding to temperature and osmotic challenges
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
Scaling Up
Red blood cells and plasma
- 3 things to know
- Paper 3
Overview
The function of red blood cells, haemoglobin and oxyhaemoglobin, why red blood cells have no nucleus and a flattened disc shape and are small and flexible, what plasma is, the glucose, amino acids, urea and carbon dioxide dissolved in it, how plasma suits its transport role, and the cells, platelets and heat it also carries.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Why does a mature red blood cell have no nucleus?
Key term
Name four dissolved substances carried in plasma.
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is the function of a red blood cell?
Model answer
To carry oxygen from the lungs to the respiring cells of the body.
- 2
Which protein inside a red blood cell binds oxygen?
Model answer
Haemoglobin.
- 3
What is formed when haemoglobin combines with oxygen, and where does this happen?
Model answer
Oxyhaemoglobin is formed, in the lungs where the oxygen concentration is high.
- 4
Why does a mature red blood cell have no nucleus?
Model answer
Leaving it out makes room for more haemoglobin, so each cell can carry more oxygen.
- 5
How does the shape of a red blood cell help it carry oxygen?
Model answer
Its flattened, dimpled disc shape gives a large surface area for its volume, so oxygen diffuses in and out quickly.
- 6
Why is it useful that red blood cells are small and flexible?
Model answer
So they can squeeze through the narrowest capillaries and reach every tissue.
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