Key term
Edexcel GCSE Combined Science Biology 1SC0
Key Concepts in Biology
Topic overviewEukaryotic and prokaryotic cellsSpecialised cells and their adaptationsMicroscopes and magnification calculationsSize, scale and units in cell biologyEnzyme action and denaturationFactors affecting enzyme activityEnzymes in synthesis and digestion, and rate calculationsDiffusion, osmosis and active transportOsmosis in potatoes and percentage change in mass
Cells and Control
Genetics
Topic overviewMeiosis and the formation of gametesDNA structure, genes and the genomeExtracting DNA from fruitAlleles, genotype and phenotypeMonohybrid crosses and sex determinationProbability and ratios from genetic crossesCauses of variation: genes and environmentThe Human Genome ProjectGenetic variation and the effects of mutation
Natural Selection and Genetic Modification
Health, Disease and the Development of Medicines
Topic overviewHealth, disease and susceptibilityPathogens and common infectionsHow pathogens spread, and the virus life cycleSexually transmitted infectionsPhysical barriers and chemical defencesThe immune system, immunisation and herd immunityAntibiotics and developing new medicinesLifestyle factors and non-communicable diseaseTreatments for cardiovascular disease
Plant Structures and Their Functions
Animal Coordination, Control and Homeostasis
Exchange and Transport in Animals
Topic overviewWhy multicellular organisms need exchange surfacesAlveoli and gas exchangeThe blood and its componentsArteries, veins and capillariesThe heart and the circulatory systemCellular respiration as an exothermic reactionAerobic and anaerobic respiration comparedInvestigating the rate of respirationCardiac output, stroke volume and heart rate
Ecosystems and Material Cycles
Animal Coordination, Control and Homeostasis
Hormonal and barrier contraception
- 3 things to know
- Paper 2
Overview
How oestrogen and progesterone in hormonal contraception prevent pregnancy, pills, injections, implants and patches, condoms and diaphragms as barrier methods, the advantages and disadvantages of each, and what perfect-use and typical-use effectiveness figures show.
What you need to know
Answer each one before you reveal it.
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Key term
Explain how hormonal contraception can make the uterus unsuitable for pregnancy.
Key term
Explain why a contraceptive pill has to be taken regularly to work.
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is hormonal contraception?
Model answer
It is the use of hormones such as oestrogen and progesterone to prevent pregnancy.
- 2
Explain how oestrogen given as a contraceptive prevents pregnancy.
Model answer
Given continuously it stops an egg maturing and being released, so there is no egg to be fertilised.
- 3
Explain how progesterone used as a contraceptive reduces the chance of fertilisation.
Model answer
It thickens the mucus at the entrance to the uterus so sperm cannot swim through to reach an egg.
- 4
Explain how hormonal contraception can make the uterus unsuitable for pregnancy.
Model answer
The hormones keep the lining of the uterus thin, so a fertilised egg cannot implant in it.
- 5
Name three ways of giving hormonal contraception other than a daily pill.
Model answer
By injection, by an implant placed under the skin, or by a patch worn on the skin.
- 6
Explain why a contraceptive pill has to be taken regularly to work.
Model answer
If doses are missed the hormone level in the blood falls, so an egg may mature and be released.
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