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
Hormones in reproduction and the menstrual cycle
- 3 things to know
- Paper 1 (Biology)
Overview
Testosterone 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.
What you need to know
Answer each one before you reveal it.
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Key term
Which is the main female reproductive hormone and where is it made?
Key term
What does FSH do, and where is it released from?
Questions from this subtopic
Each one with the model answer underneath.
- 1
Which is the main male reproductive hormone and where is it made?
Model answer
Testosterone, made in the testes.
- 2
What does testosterone do?
Model answer
It stimulates sperm production and causes the male secondary sexual characteristics to develop at puberty.
- 3
Which is the main female reproductive hormone and where is it made?
Model answer
Oestrogen, made in the ovaries.
- 4
Give two effects of oestrogen at puberty.
Model answer
It causes the female secondary sexual characteristics to develop and it starts the menstrual cycle.
- 5
What does FSH do, and where is it released from?
Model answer
It is released from the pituitary gland and makes an egg mature inside a follicle in the ovary, as well as stimulating the ovary to make oestrogen.
- 6
What is the role of progesterone in the menstrual cycle?
Model answer
It maintains the thick lining of the uterus so it is ready for a fertilised egg to implant.
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