Key term
OCR A-Level Biology B H422
The Developing Cell: Cell Division and Cell Differentiation
The Developing Individual: Meiosis, Growth and Development
The Development of Species: Evolution and Classification
Cells and Microscopy
Topic overviewMicroscopy and the cell theoryBlood smears, staining and microscope drawingsBlood cells and their structureMagnification and measuring cellsHaemocytometer cell counts and dilutionsFlow cytometry in blood analysisUltrastructure of the animal cellPlant and prokaryotic cellsMembrane lipids and the fluid mosaic modelMovement of molecules across membranesThe roles of membranes and the secretion of proteins
Water and Its Importance in Plants and Animals
Proteins and Enzymes
Nucleic Acids
Patterns of Inheritance
Population Genetics and Epigenetics
Gene Technologies
The Principles and Importance of Homeostasis
The Hormonal Control of Blood Glucose and the Management of Diabetes
Kidney Functions and Malfunctions
Topic overviewExcretion and the gross structure of the kidneyThe nephron: ultrafiltration and selective reabsorptionInvestigating the composition of urine, plasma and filtrateOsmoregulation and the action of ADHThe kidney as an endocrine gland and kidney failureDialysis, transplantation and the future of transplant surgery
The Cellular Basis of Cancer and Treatment
Respiratory Diseases and Treatment
Cellular Respiration
Metabolism and Exercise
Topic overviewThe consequences of exercise on the bodyAerobic fitness and VO₂ maxTraining, F.I.T.T. factors and investigating fitnessEnhancing athletic performanceHaemoglobin and the transport of oxygenOxygen dissociation curves of different respiratory pigmentsOxygen deficit and oxygen debtThe structure of skeletal muscleThe sliding filament theory of muscle contraction
Pathogenic Microorganisms
The Immune System
Controlling Communicable Diseases
Photosynthesis, Food Production and Management of the Environment
Topic overviewChloroplast ultrastructure and photosynthetic pigmentsThe light-dependent stage of photosynthesisThe Calvin cycleInvestigating the factors affecting photosynthesisThe Hill reaction and DCPIPUsing TP and GP to build carbohydrates, lipids and amino acidsThe compensation point and crop productionMicroorganisms, the nitrogen cycle and biosensorsBiomass transfer and efficiency in food productionRuminants in the human food chainFarms as ecosystems and the conflict with conservationDeflected succession and measuring biodiversity
The Impact of Population Increase
Planning and Implementing Practical Work
Analysing and Evaluating Practical Results
Practical Skills, Apparatus and Techniques
Topic overviewInvestigative approaches and working safelyFollowing instructions, recording and presenting dataResearch, referencing and processing data with softwareMeasuring mass, volume, time, temperature, length and pHColorimeters and potometersLaboratory glassware and serial dilutionsLight microscopy, graticules and biological drawingQualitative reagents for biological moleculesChromatography and electrophoresisAseptic technique and dissectionWhole-organism responses, fieldwork sampling and data logging
Fertility and Assisted Reproduction
The Effects of Ageing on the Reproductive System
Plant Reproduction
The Nervous System and the Identification and Consequences of Damage
Topic overviewOrganisation of the nervous system and nervous tissueThe structure and function of the human brainThe structure of motor, sensory and relay neuronesResting potential and the action potentialSynapses and the integration of responsesReflexes, reaction times and their investigationBrain scans and the consequences of nervous system damageDrugs, brain function and dependency
Monitoring Visual Function
The Effect of Ageing on the Nervous System
The Heart and Monitoring Heart Function
Transport Systems in Mammals
Gas Exchange in Mammals and Plants
The Developing Individual: Meiosis, Growth and Development
- 5 subtopics
- 15 things to know
- Components 01, 02 and 03
What The Developing Individual: Meiosis, Growth and Development covers
The Developing Individual: Meiosis, Growth and Development is examined in all three written papers — the specification states that Components 01, 02 and 03 can each assess content from any of the five modules, so nothing is confined to one paper. It covers meiosis, haploid gametes and genetic variation, the stages of meiosis, antenatal care and diet in pregnancy, alcohol, smoking and monitoring fetal growth and prenatal screening and karyotypes.
Where it is assessed
Components 01, 02 and 03
Every module can be assessed on any of the three papers.
Check the OCR specification ↗The 5 subtopics
Each one has its own page.
- Meiosis, haploid gametes and genetic variationRecall questions on meiosis, haploid cells and homologous pairs, where meiosis happens in humans and flowering plants, fertilisation, crossing over and chiasmata, independent assortment at metaphase 1 and 2, the 2²³ chromosome combinations, and random fertilisation as a source of variation.Open →
- The stages of meiosisRecall questions on the interphase before meiosis, the events of prophase 1 and bivalent formation, what separates at each anaphase, and how the products compare with mitosis.Open →
- Antenatal care and diet in pregnancyRecall questions on antenatal, pre-conceptual and post-conceptual care, folic acid supplements, urine and blood pressure checks for pre-eclampsia, rubella immunity and body mass, and the extra protein, calcium, iron, vitamin C, vitamin A and energy needed in pregnancy.Open →
- Alcohol, smoking and monitoring fetal growthRecall questions on fetal alcohol syndrome and how ethanol crosses the placenta, how carbon monoxide and nicotine restrict fetal growth, the other risks of smoking, why ultrasound is used rather than X-rays, biparietal diameter and crown-rump length, and reading fetal growth charts and centiles.Open →
- Prenatal screening and karyotypesRecall questions on the advantages and limitations of fetal ultrasonography, amniocentesis and chorionic villus sampling compared, preparing a karyotype, the karyotypes of Down's, Klinefelter's and Turner's syndromes, and why a karyotype cannot reveal cystic fibrosis.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Explain why meiosis is essential if the chromosome number is to stay the same from one generation to the next.
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Describe the main events of prophase 1.
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Give two ways in which anaphase 1 differs from anaphase in mitosis.
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Why is vitamin A needed in pregnancy, and why are liver and high-dose supplements avoided?
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Why are repeated scans more informative than a single measurement?
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Describe how a karyotype is prepared from a cell sample.
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State the daily folic acid supplement advised in the United Kingdom before conception, and how long it is continued.
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Explain how alcohol drunk by the mother reaches the fetus.
Process
Why are amniocentesis and chorionic villus sampling described as invasive procedures?
Key term
What is meant by a haploid cell?
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What happens during the interphase that precedes meiosis?
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Why is a woman's urine tested at every antenatal appointment?
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Why is a fetus more vulnerable to alcohol than its mother is?
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Why can a karyotype reveal Down's syndrome but not cystic fibrosis?
Take The Developing Individual: Meiosis, Growth and Development further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Meiosis 1 vs Meiosis 2
Meiosis 1: the reduction division, in which the members of each homologous pair are pulled to opposite poles so the chromosome number is halved. Meiosis 2: the division in which sister chromatids are pulled apart at the equator, much as in mitosis, with no further halving of the chromosome number.
Crossing over vs Independent assortment
Crossing over: the exchange of matching sections of DNA between homologous chromosomes where they touch at a chiasma within a bivalent. Independent assortment: the random orientation of each homologous pair at the equator, so whole maternal and paternal chromosomes are shuffled between the two poles.
Amniocentesis vs Chorionic villus sampling
Amniocentesis: drawing off a little of the fluid surrounding the fetus from about fifteen weeks, which carries a lower risk of miscarriage but gives a later result. Chorionic villus sampling: taking a small piece of placental tissue from about eleven weeks, which gives an earlier and faster result but carries a higher risk of miscarriage.
Questions from this topic
Each one with the model answer underneath.
- 1
Define meiosis.
Model answer
Meiosis is a form of nuclear division in which one diploid cell gives rise to four haploid nuclei, each with half the chromosome number of the parent cell.
- 2
What is meant by a haploid cell?
Model answer
A haploid cell contains a single set of chromosomes, one of each homologous pair, and is written as n.
- 3
What is a homologous pair of chromosomes?
Model answer
A homologous pair is two chromosomes of the same size carrying the same genes at the same loci, one inherited from each parent, though the alleles they carry may differ.
- 4
State the number of chromosomes in a human gamete and in a human zygote.
Model answer
A human gamete has 23 chromosomes and a human zygote has 46.
- 5
Explain why meiosis is essential if the chromosome number is to stay the same from one generation to the next.
Model answer
Fertilisation combines two nuclei and so doubles the chromosome number, and meiosis halves it beforehand, so the zygote receives the normal diploid number rather than twice it.
- 6
In which organs does meiosis take place in humans?
Model answer
It takes place in the seminiferous tubules of the testes in males and in the ovaries in females.
What is inside Levo
Six ways to work the same material.
The Developing Individual: Meiosis, Growth and Development revision questions
- What does The Developing Individual: Meiosis, Growth and Development cover in OCR A-Level Biology B?
- 5 subtopics: meiosis, haploid gametes and genetic variation, the stages of meiosis, antenatal care and diet in pregnancy, alcohol, smoking and monitoring fetal growth and prenatal screening and karyotypes. Each one has its own page with questions and model answers.
- How is The Developing Individual: Meiosis, Growth and Development organised?
- By the OCR H422 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in The Developing Individual: Meiosis, Growth and Development, 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.
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