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
- 9 subtopics
- 27 things to know
- Paper 1
What Genetics covers
Genetics is examined in Paper 1, Biology 1. It covers meiosis, DNA structure, genes and the genome, extracting DNA from fruit, alleles, genotype and phenotype, monohybrid crosses, sex determination and probability, genetic and environmental variation, the Human Genome Project and mutation.
Where it is assessed
Paper 1
Biology 1: Biology in Combined Science: 1 hour 10 minutes, 60 marks, 16.67% of the qualification.
Check the Pearson Edexcel specification ↗The 9 subtopics
Each one has its own page.
- Meiosis and the formation of gametesWhere meiosis takes place, the four haploid daughter cells it makes with half the chromosome number, the 23 chromosomes in a human gamete, why gametes must be haploid for fertilisation, and how the random sharing of chromosomes makes gametes and children genetically different.Open →
- DNA structure, genes and the genomeDNA 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.Open →
- Extracting DNA from fruitExtracting DNA from fruit by mashing, adding detergent and salt, filtering and pouring on ice-cold ethanol, why the DNA comes out of solution as a white stringy layer, and why the mixture is stirred gently.Open →
- Alleles, genotype and phenotypeAlleles and why individuals of a species differ, dominant and recessive alleles and how a recessive allele can be carried unseen, chromosomes and genes, homozygous and heterozygous, genotype and phenotype, gametes and zygotes, and why one phenotype can hide different genotypes.Open →
- Monohybrid crosses and sex determinationMonohybrid inheritance and Punnett squares, the ratios from heterozygous and homozygous crosses, reading a family pedigree, and how the X and Y chromosomes decide sex.Open →
- Probability and ratios from genetic crossesThe probabilities and percentages expected from heterozygous and homozygous recessive crosses, turning offspring counts into whole-number ratios, and why real results rarely match the prediction.Open →
- Causes of variation: genes and environmentCharacteristics controlled by many genes such as height and their continuous range, genetic variation from mutation and sexual reproduction, acquired characteristics and environmental variation, identical twins, and presenting variation with frequency tables, histograms, bar charts and the modal class.Open →
- The Human Genome ProjectThe aim and outcomes of the Human Genome Project, testing for inherited disorders and predicting disease risk, personalised medicine and new drug treatments, tracing human migration, and concerns about insurers, employers and knowing the risk of an untreatable disease.Open →
- Genetic variation and the effects of mutationExtensive genetic variation within a population, mutations as random changes in base sequence and the source of new variation, why most mutations have no effect on the phenotype, the rare ones that stop a protein working, and mutations that give an advantage.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
How do a gene and an allele differ, when is an allele dominant or recessive, and what does homozygous mean?
Key term
What do heterozygous, genotype, phenotype and gamete each mean?
Key term
How many daughter cells are formed from one parent cell by meiosis?
Key term
Why is fruit such as kiwi mashed at the start of extracting DNA from it?
Key term
What is written along the top and down the side of a Punnett square?
Key term
Two heterozygous parents are crossed. What is the probability that a child shows the recessive characteristic?
Key term
Give an example of a human characteristic that is controlled by many genes.
Key term
State one outcome of the Human Genome Project.
Key term
What is the ultimate source of new genetic variation in a population?
Key term
How does the chromosome number of a cell made by meiosis compare with that of the parent cell?
Key term
What is the repeating unit from which the DNA polymer is built?
Key term
Why is detergent added to the mashed fruit when extracting DNA?
Key term
Two heterozygous parents are crossed for a characteristic controlled by one gene. What ratio of phenotypes is expected in the offspring?
Numbers
Two heterozygous parents are crossed. What percentage of the offspring are expected to show the dominant characteristic?
Key term
Explain why a simple genetic cross diagram cannot predict a person's height.
Key term
Explain how knowing the position of a gene helps doctors test for an inherited disorder.
Key term
What is a mutation?
Key term
What is meant by a haploid cell?
Key term
Describe the overall shape of a DNA molecule.
Key term
Why is salt added to the mixture when extracting DNA from fruit?
Key term
What is an allele?
Key term
A heterozygous parent is crossed with a homozygous recessive parent. What ratio of phenotypes is expected?
Numbers
Two heterozygous parents are crossed. What percentage of their children are expected to be heterozygous?
Key term
Explain why brothers and sisters vary so widely in characteristics such as skin colour.
Key term
Describe how the Human Genome Project can help predict a person's risk of disease.
Key term
What effect do most mutations have on the phenotype?
Take Genetics further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Genotype vs Phenotype
Genotype: combination of alleles an organism has for a characteristic. Phenotype: observable characteristic the organism actually shows.
Homozygous vs Heterozygous
Homozygous: having two identical alleles of a particular gene. Heterozygous: having two different alleles of a particular gene.
Dominant allele vs Recessive allele
Dominant allele: version expressed in the characteristic even when only one copy is present. Recessive allele: version only expressed when two copies are present.
Questions from this topic
Each one with the model answer underneath.
- 1
In which organs of the body does meiotic cell division take place?
Model answer
It takes place in the reproductive organs, where gametes are made.
- 2
How many daughter cells are formed from one parent cell by meiosis?
Model answer
Four daughter cells are formed.
- 3
How does the chromosome number of a cell made by meiosis compare with that of the parent cell?
Model answer
Each daughter cell has half the number of chromosomes of the parent cell.
- 4
What is meant by a haploid cell?
Model answer
A haploid cell contains one copy of each chromosome, which is half the full number.
- 5
A human body cell contains 46 chromosomes. How many chromosomes are in a human gamete?
Model answer
A human gamete contains 23 chromosomes.
- 6
Why are the gametes produced by meiosis genetically different from one another?
Model answer
The chromosomes are shared out at random, so each gamete receives a different combination of alleles.
What is inside Levo
Six ways to work the same material.
Genetics revision questions
- What does Genetics cover in Edexcel GCSE Combined Science Biology?
- 9 subtopics: meiosis and the formation of gametes, dna structure, genes and the genome, extracting dna from fruit, alleles, genotype and phenotype, monohybrid crosses and sex determination, probability and ratios from genetic crosses, causes of variation: genes and environment, the human genome project and genetic variation and the effects of mutation. Each one has its own page with questions and model answers.
- How is Genetics organised?
- By the Edexcel 1SC0 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Genetics, on a schedule.
Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.
Or £46 a year, about £3.83 a month. Cancel anytime.