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
Meiosis and the formation of gametes
- 3 things to know
- Paper 1
Overview
Where 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.
What you need to know
Answer each one before you reveal it.
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Key term
How does the chromosome number of a cell made by meiosis compare with that of the parent cell?
Key term
What is meant by a haploid cell?
Questions from this subtopic
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.
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