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
Genetics
DNA structure, genes and the genome
- 3 things to know
- Paper 1
Overview
DNA as a double helix polymer of nucleotides made of a sugar, a phosphate and one of four bases, complementary base pairing held by weak hydrogen bonds, genes as sections of DNA coding for proteins, the genome, and why people with the same genes can differ.
What you need to know
Answer each one before you reveal it.
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Key term
What is the repeating unit from which the DNA polymer is built?
Key term
Describe the overall shape of a DNA molecule.
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is the repeating unit from which the DNA polymer is built?
Model answer
DNA is built from repeating units called nucleotides.
- 2
Describe the overall shape of a DNA molecule.
Model answer
Two strands are coiled around each other to form a double helix.
- 3
Name the three parts that make up a single DNA nucleotide.
Model answer
A sugar, a phosphate group and one of four bases.
- 4
To which part of a nucleotide is the base attached?
Model answer
The base is attached to the sugar.
- 5
How many different bases are found in DNA?
Model answer
There are four different bases.
- 6
What type of bond holds a pair of bases together across the two strands?
Model answer
Weak hydrogen bonds hold each base pair together.
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