{"id":37971,"date":"2026-04-08T17:06:08","date_gmt":"2026-04-08T10:06:08","guid":{"rendered":"https:\/\/times.edu.vn\/?p=37971"},"modified":"2026-05-08T15:50:07","modified_gmt":"2026-05-08T08:50:07","slug":"igcse-genetics-questions","status":"publish","type":"post","link":"https:\/\/times.edu.vn\/en\/igcse\/igcse-genetics-questions\/","title":{"rendered":"IGCSE Biology Genetics Questions 2026: Punnett Squares + Pedigree A*"},"content":{"rendered":"<p><strong><a href=\"https:\/\/times.edu.vn\/en\/igcse\/what-is-igcse-a-comprehensive-guide-for-students\/\">IGCSE<\/a><\/strong><strong>\u00a0genetics questions<\/strong> mainly test how accurately you apply inheritance rules, not how much you can memorize.<\/p>\n<p>You\u2019re expected to define core terms like allele, genotype, phenotype, homozygous and heterozygous, then use a Punnett square to solve a monohybrid cross and state genotype\/phenotype ratios.<\/p>\n<p>Higher-mark items often add codominance, sex-linked disorders, DNA-to-trait reasoning, and pedigree chart interpretation, where clear evidence-based explanations earn the marks.<\/p>\n<p>The most reliable way to score is a consistent method: Translate wording into genotypes, build the Punnett square cleanly, and write probabilities and ratios with precise terminology.<\/p>\n<h2><strong>Solving IGCSE genetics questions and monohybrid inheritance<\/strong><\/h2>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-38003\" src=\"https:\/\/times.edu.vn\/wp-content\/uploads\/2026\/04\/3-11.webp\" alt=\"IGCSE Genetics Questions 2026: A Simple Guide to Solving Inheritance Problems with Confidence\" width=\"1000\" height=\"558\" srcset=\"https:\/\/times.edu.vn\/wp-content\/uploads\/2026\/04\/3-11.webp 1000w, https:\/\/times.edu.vn\/wp-content\/uploads\/2026\/04\/3-11-300x167.webp 300w, https:\/\/times.edu.vn\/wp-content\/uploads\/2026\/04\/3-11-768x429.webp 768w\" sizes=\"auto, (max-width: 1000px) 100vw, 1000px\" \/><\/p>\n<p>IGCSE genetics questions are rarely \u201chard biology\u201d; they are usually \u201cprecision thinking under time pressure.\u201d Based on our years of practical tutoring at Times Edu, the top scorers separate <strong>content recall<\/strong>\u00a0(definitions like allele\u00a0and genotype) from <strong>process marks<\/strong>\u00a0(setting up the Punnett Square\u00a0correctly, then stating probabilities cleanly).<\/p>\n<p>A critical detail most students overlook in the 2026 exam cycle is that Cambridge <sup><a href=\"#tooltip-ref-1\" class=\"tooltip-link\" data-tooltip=\"https:\/\/www.cambridgeinternational.org\/\">[1]<\/a><\/sup>\u00a0updates syllabuses in \u201cversioned\u201d documents; small wording changes can shift what examiners accept as \u201ccomplete\u201d phrasing.<\/p>\n<p>Cambridge has a 2026\u20132028 Biology (0610) syllabus <sup><a href=\"#tooltip-ref-2\" class=\"tooltip-link\" data-tooltip=\"https:\/\/www.cambridgeinternational.org\/Images\/697203-2026-2028-syllabus.pdf\">[2]<\/a><\/sup>\u00a0and even issued an update note indicating the latest version and publication timing.<\/p>\n<h3><strong>What examiners are actually rewarding in IGCSE inheritance questions<\/strong><\/h3>\n<p>From our direct experience with international school curricula, marks are usually split across three layers:<\/p>\n<ul>\n<li><strong>Setup marks<\/strong>: Correct symbols, correct gametes, correctly structured Punnett Square<\/li>\n<li><strong>Reasoning marks<\/strong>: Correct probability language (e.g., \u201c1\/4\u201d or \u201c25%\u201d) and correct link to <strong>phenotype<\/strong><\/li>\n<li><strong>Communication marks<\/strong>: Precise terminology (homozygous, heterozygous, dominant, recessive, codominance) and no contradictions<\/li>\n<\/ul>\n<h3><strong>Common misconceptions that lose easy marks<\/strong><\/h3>\n<ul>\n<li>Confusing <strong>genotype<\/strong>\u00a0(letters) with <strong>phenotype<\/strong>\u00a0(observable trait).<\/li>\n<li>Using the <strong>trait letter<\/strong>\u00a0inconsistently (switching from \u201cT\/t\u201d to \u201cA\/a\u201d mid-solution).<\/li>\n<li>Forgetting that gametes carry <strong>one allele<\/strong>\u00a0per gene, not two.<\/li>\n<li>Writing a ratio without stating what the ratio refers to\u00a0(genotype vs phenotype).<\/li>\n<\/ul>\n<h3><strong>A rapid \u201cmark-safe\u201d workflow for monohybrid problems<\/strong><\/h3>\n<p>The pedagogical approach we recommend for high-achievers is a repeatable 6-step routine:<\/p>\n<ul>\n<li>Identify the trait and state <strong>dominant<\/strong>\u00a0vs <strong>recessive<\/strong>\u00a0clearly.<\/li>\n<li>Assign alleles using one letter (e.g., <strong>T<\/strong>\u00a0and <strong>t<\/strong>).<\/li>\n<li>Deduce parent <strong>genotypes<\/strong>\u00a0from the wording (especially \u201cpure-breeding,\u201d \u201ccarrier,\u201d \u201cshows the trait\u201d).<\/li>\n<li>Write gametes for each parent (one allele each).<\/li>\n<li>Complete the <strong>Punnett Square<\/strong>.<\/li>\n<li>State outcomes as <strong>genotype ratio<\/strong>, <strong>phenotype ratio<\/strong>, and one probability sentence.<\/li>\n<\/ul>\n<p><strong style=\"color: #f00;\">&gt;&gt;&gt; Read more:<\/strong> <a class=\"xem-them-link\" href=\"https:\/\/times.edu.vn\/en\/igcse\/igcse-biology-command-words\/\">IGCSE Biology Command Words<\/a> 2026: How to Understand Questions and Answer More Accurately<\/p>\n<h2><strong>Predicting genotypes and phenotypes using Punnett squares<\/strong><\/h2>\n<p>Most IGCSE genetics questions are algebra in disguise: You are combining alleles and counting outcomes. Your job is to prevent avoidable errors by using a consistent layout every time.<\/p>\n<h3><strong>Terminology you must use correctly (and fast)<\/strong><\/h3>\n<table>\n<tbody>\n<tr>\n<th colspan=\"1\" rowspan=\"1\"><strong>Term<\/strong><\/th>\n<th colspan=\"1\" rowspan=\"1\"><strong>Exam-safe meaning<\/strong><\/th>\n<th colspan=\"1\" rowspan=\"1\"><strong>What students often do wrong<\/strong><\/th>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\"><strong>Allele<\/strong><\/td>\n<td colspan=\"1\" rowspan=\"1\">Alternative form of a gene (e.g., T or t)<\/td>\n<td colspan=\"1\" rowspan=\"1\">Define \u201cgene\u201d instead of allele<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\"><strong>Genotype<\/strong><\/td>\n<td colspan=\"1\" rowspan=\"1\">Allele combination (e.g., Tt)<\/td>\n<td colspan=\"1\" rowspan=\"1\">Describe appearance instead<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\"><strong>Phenotype<\/strong><\/td>\n<td colspan=\"1\" rowspan=\"1\">Observable trait (e.g., tall plant)<\/td>\n<td colspan=\"1\" rowspan=\"1\">Write letters (that\u2019s genotype)<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\"><strong>Homozygous<\/strong><\/td>\n<td colspan=\"1\" rowspan=\"1\">Same alleles (TT or tt)<\/td>\n<td colspan=\"1\" rowspan=\"1\">Mix up with \u201cdominant\u201d<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\"><strong>Heterozygous<\/strong><\/td>\n<td colspan=\"1\" rowspan=\"1\">Different alleles (Tt)<\/td>\n<td colspan=\"1\" rowspan=\"1\">Forget it can still show dominant phenotype<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\"><strong>Punnett Square<\/strong><\/td>\n<td colspan=\"1\" rowspan=\"1\">Predicts allele combinations in offspring<\/td>\n<td colspan=\"1\" rowspan=\"1\">Put two alleles into one gamete<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3><strong>The model monohybrid cross: Tt \u00d7 Tt<\/strong><\/h3>\n<p>If both parents are <strong>heterozygous<\/strong>, each parent produces gametes <strong>T<\/strong>\u00a0and <strong>t<\/strong>. The Punnett Square gives: TT, Tt, Tt, tt.<\/p>\n<table>\n<tbody>\n<tr>\n<th colspan=\"1\" rowspan=\"1\"><strong>Outcome type<\/strong><\/th>\n<th colspan=\"1\" rowspan=\"1\"><strong>Result<\/strong><\/th>\n<th colspan=\"1\" rowspan=\"1\"><strong>How to write it for marks<\/strong><\/th>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">Genotype ratio<\/td>\n<td colspan=\"1\" rowspan=\"1\">1 TT : 2 Tt : 1 tt<\/td>\n<td colspan=\"1\" rowspan=\"1\">\u201cGenotype ratio = 1:2:1\u201d<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">Phenotype ratio (T dominant)<\/td>\n<td colspan=\"1\" rowspan=\"1\">3 dominant : 1 recessive<\/td>\n<td colspan=\"1\" rowspan=\"1\">\u201cPhenotype ratio = 3:1\u201d<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">Recessive probability<\/td>\n<td colspan=\"1\" rowspan=\"1\">1\/4<\/td>\n<td colspan=\"1\" rowspan=\"1\">\u201c25% chance of recessive phenotype\u201d<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3><strong>\u201cProcess-mark language\u201d that examiners like<\/strong><\/h3>\n<p>Use one of these sentence frames (do not improvise under stress):<\/p>\n<ul>\n<li>\u201cThere is a <strong>1\/4<\/strong>\u00a0probability the offspring will be <strong>tt<\/strong>, so <strong>1\/4<\/strong>\u00a0show the recessive phenotype.\u201d<\/li>\n<li>\u201cBecause the offspring is <strong>heterozygous (Tt)<\/strong>, it shows the dominant phenotype but carries the recessive allele.\u201d<\/li>\n<\/ul>\n<h3><strong>How to deduce parental genotypes from wording<\/strong><\/h3>\n<table>\n<tbody>\n<tr>\n<th colspan=\"1\" rowspan=\"1\"><strong>Wording in question<\/strong><\/th>\n<th colspan=\"1\" rowspan=\"1\"><strong>Parent genotype implication<\/strong><\/th>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">\u201cPure-breeding dominant\u201d<\/td>\n<td colspan=\"1\" rowspan=\"1\"><strong>TT<\/strong>\u00a0(homozygous dominant)<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">\u201cPure-breeding recessive\u201d<\/td>\n<td colspan=\"1\" rowspan=\"1\"><strong>tt<\/strong>\u00a0(homozygous recessive)<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">\u201cCarrier\u201d (recessive trait)<\/td>\n<td colspan=\"1\" rowspan=\"1\"><strong>Tt<\/strong>\u00a0(heterozygous)<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">\u201cShows recessive trait\u201d<\/td>\n<td colspan=\"1\" rowspan=\"1\"><strong>tt<\/strong>\u00a0only<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">\u201cShows dominant trait\u201d<\/td>\n<td colspan=\"1\" rowspan=\"1\"><strong>TT or Tt<\/strong>\u00a0(need more info)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>A critical detail most students overlook in the 2026 exam cycle is that many structured questions now embed genotype deduction inside a short case study, not a single sentence.<\/p>\n<p>You must annotate the stem and convert words into genotypes before you draw the Punnett Square.<\/p>\n<p><strong style=\"color: #f00;\">&gt;&gt;&gt; Read more:<\/strong> <a class=\"xem-them-link\" href=\"https:\/\/times.edu.vn\/en\/igcse\/igcse-biology-mock-improvement-plan\/\">IGCSE Biology Mock Improvement Plan for<\/a> 2026: Practical Steps to Improve After Every Mock Exam<\/p>\n<h2><strong>Understanding codominance and sex-linked genetic disorders<\/strong><\/h2>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-38007\" src=\"https:\/\/times.edu.vn\/wp-content\/uploads\/2026\/04\/4-11.webp\" alt=\"IGCSE Genetics Questions 2026: A Simple Guide to Solving Inheritance Problems with Confidence\" width=\"1000\" height=\"558\" srcset=\"https:\/\/times.edu.vn\/wp-content\/uploads\/2026\/04\/4-11.webp 1000w, https:\/\/times.edu.vn\/wp-content\/uploads\/2026\/04\/4-11-300x167.webp 300w, https:\/\/times.edu.vn\/wp-content\/uploads\/2026\/04\/4-11-768x429.webp 768w\" sizes=\"auto, (max-width: 1000px) 100vw, 1000px\" \/><\/p>\n<p>IGCSE genetics questions become trickier when the pattern is not simple dominant\/recessive. Two high-frequency patterns are <strong>codominance<\/strong>\u00a0and <strong>sex linkage<\/strong>.<\/p>\n<h3><strong>Codominance: <\/strong><strong>T<\/strong><strong>he examiner\u2019s favorite \u201cdefinition + application\u201d combo<\/strong><\/h3>\n<p>Codominance means <strong>both alleles are expressed in the phenotype<\/strong>\u00a0in a heterozygote. You do not describe one allele as \u201cstronger\u201d or \u201cpartly dominant\u201d; you state that both show.<\/p>\n<table>\n<tbody>\n<tr>\n<th colspan=\"1\" rowspan=\"1\"><strong>Pattern<\/strong><\/th>\n<th colspan=\"1\" rowspan=\"1\"><strong>Heterozygote phenotype<\/strong><\/th>\n<th colspan=\"1\" rowspan=\"1\"><strong>Typical exam example<\/strong><\/th>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">Complete dominance<\/td>\n<td colspan=\"1\" rowspan=\"1\">Looks like dominant<\/td>\n<td colspan=\"1\" rowspan=\"1\">Pea seed shape<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">Incomplete dominance<\/td>\n<td colspan=\"1\" rowspan=\"1\">Intermediate\/blended<\/td>\n<td colspan=\"1\" rowspan=\"1\">Some flower colors (depends on spec)<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\"><strong>Codominance<\/strong><\/td>\n<td colspan=\"1\" rowspan=\"1\"><strong>Both traits visible<\/strong><\/td>\n<td colspan=\"1\" rowspan=\"1\">Blood groups (A and B)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>How to answer codominance questions without losing marks:<\/p>\n<ul>\n<li>Define codominance in one sentence.<\/li>\n<li>Identify the heterozygote genotype.<\/li>\n<li>State the phenotype shows both alleles\u2019 effects.<\/li>\n<\/ul>\n<h3><strong>Sex-linked characteristics (X-linked): <\/strong><strong>R<\/strong><strong>ules that prevent confusion<\/strong><\/h3>\n<p>In humans, sex is commonly represented as <strong>XX (female)<\/strong>\u00a0and <strong>XY (male)<\/strong>. Cambridge Biology syllabuses explicitly include inheritance content and expect accurate use of sex chromosomes in reasoning.<\/p>\n<p>Exam rules that keep you safe:<\/p>\n<ul>\n<li><strong>Males (XY)<\/strong>\u00a0have only one X chromosome, so one recessive allele on X can show in phenotype.<\/li>\n<li><strong>Females (XX)<\/strong>\u00a0need two recessive alleles to show an X-linked recessive trait.<\/li>\n<li>Fathers pass <strong>X to daughters<\/strong>\u00a0and <strong>Y to sons<\/strong>\u00a0(this is a frequent 1-mark line).<\/li>\n<\/ul>\n<h3><strong>High-frequency structure for X-linked disorder questions<\/strong><\/h3>\n<p>When the question gives a family scenario, do this:<\/p>\n<ul>\n<li>Write allele on the X chromosome clearly (e.g., <strong>X\u1d3a<\/strong>\u00a0and <strong>X\u207f<\/strong>).<\/li>\n<li>Write each person\u2019s genotype (male: X?Y, female: X?X?).<\/li>\n<li>Use a Punnett Square only if asked; otherwise, show inheritance logic and probabilities.<\/li>\n<\/ul>\n<p><strong style=\"color: #f00;\">&gt;&gt;&gt; Read more:<\/strong> <a class=\"xem-them-link\" href=\"https:\/\/times.edu.vn\/en\/igcse\/igcse-biology-past-paper-strategy\/\">IGCSE Biology Past Paper Strategy for<\/a> 2026: How to Use Past Papers for Better Exam Results<\/p>\n<h2><strong>The role of DNA and alleles in determining inherited characteristics<\/strong><\/h2>\n<p>Many IGCSE genetics questions mix classical inheritance with molecular statements about DNA, genes, and proteins. You need short, accurate links.<\/p>\n<p>Cambridge\u2019s Biology syllabus positions genetics inside a broader foundation of biological principles and skills, so molecular phrasing must stay precise.<\/p>\n<h3><strong>What to say (and not say) about genes, DNA, and alleles<\/strong><\/h3>\n<p>Use this \u201cdefinition ladder\u201d in answers:<\/p>\n<ul>\n<li><strong>DNA<\/strong>: Molecule that carries genetic information (base sequence matters).<\/li>\n<li><strong>Gene<\/strong>: Length of DNA that codes for a protein (or functional product, depending on level).<\/li>\n<li><strong>Allele<\/strong>: Different versions of a gene caused by different DNA base sequences.<\/li>\n<li><strong>Protein<\/strong>: Affects cell structure\/function and can produce a phenotype.<\/li>\n<\/ul>\n<p>Common misconception: \u201cAlleles are made of proteins.\u201d They are not; alleles are versions of genes, and genes are DNA.<\/p>\n<h3><strong>A mark-safe causal chain for longer explanations<\/strong><\/h3>\n<p>Use a 3-step chain, each as a short sentence:<\/p>\n<ul>\n<li>\u201cA mutation changes the DNA base sequence in a gene.\u201d<\/li>\n<li>\u201cThis can change the amino acid sequence of the protein.\u201d<\/li>\n<li>\u201cThe altered protein can change the phenotype and affect survival or reproduction.\u201d<\/li>\n<\/ul>\n<p>This structure also supports variation-and-selection questions, where the examiner wants the link from genetic variation to natural selection (not vague statements about \u201cadapting\u201d).<\/p>\n<p><strong style=\"color: #f00;\">&gt;&gt;&gt; Read more:<\/strong> <a class=\"xem-them-link\" href=\"https:\/\/times.edu.vn\/en\/igcse\/igcse-biology-explain-questions\/\">IGCSE Biology Explain Questions<\/a> : How to Write Clear, Effective Answers in Exams in 2026<\/p>\n<h2><strong>Interpreting pedigree diagrams and family trees in biology exams<\/strong><\/h2>\n<p>Pedigree questions look visual, but they are rule-based. Your aim is to identify whether a trait is <strong>dominant<\/strong>, <strong>recessive<\/strong>, or <strong>sex-linked<\/strong>, then justify it using evidence from the pedigree.<\/p>\n<h3><strong>Pedigree Chart: <\/strong><strong>T<\/strong><strong>he fastest decision checklist<\/strong><\/h3>\n<p>Use this table as your decision tool under exam timing:<\/p>\n<table>\n<tbody>\n<tr>\n<th colspan=\"1\" rowspan=\"1\"><strong>Pattern in Pedigree Chart<\/strong><\/th>\n<th colspan=\"1\" rowspan=\"1\"><strong>Likely inheritance<\/strong><\/th>\n<th colspan=\"1\" rowspan=\"1\"><strong>Why it matters<\/strong><\/th>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">Trait appears in every generation<\/td>\n<td colspan=\"1\" rowspan=\"1\">Dominant (often)<\/td>\n<td colspan=\"1\" rowspan=\"1\">No \u201cskipping\u201d<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">Trait skips generations<\/td>\n<td colspan=\"1\" rowspan=\"1\">Recessive (often)<\/td>\n<td colspan=\"1\" rowspan=\"1\">Carriers exist<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">More males affected than females<\/td>\n<td colspan=\"1\" rowspan=\"1\">X-linked recessive (possible)<\/td>\n<td colspan=\"1\" rowspan=\"1\">Males express with one allele<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">Affected father \u2192 all daughters affected<\/td>\n<td colspan=\"1\" rowspan=\"1\">X-linked dominant (possible)<\/td>\n<td colspan=\"1\" rowspan=\"1\">Father gives X to all daughters<\/td>\n<\/tr>\n<tr>\n<td colspan=\"1\" rowspan=\"1\">Two unaffected parents have affected child<\/td>\n<td colspan=\"1\" rowspan=\"1\">Recessive<\/td>\n<td colspan=\"1\" rowspan=\"1\">Both parents carriers<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3><strong>How to write pedigree reasoning for marks (not just the answer)<\/strong><\/h3>\n<p>From our direct experience with international school curricula, examiners reward explicit \u201cevidence lines.\u201d Use these templates:<\/p>\n<ul>\n<li>\u201cThe trait is likely <strong>recessive<\/strong>\u00a0because two unaffected parents have an affected child, which implies both parents are <strong>heterozygous carriers<\/strong>.\u201d<\/li>\n<li>\u201cThe trait is unlikely to be dominant because it <strong>skips a generation<\/strong>.\u201d<\/li>\n<li>\u201cAn X-linked recessive pattern is supported if affected individuals are mostly male and unaffected females can have affected sons.\u201d<\/li>\n<\/ul>\n<h3><strong>Typical 4\u20136 mark pedigree response structure<\/strong><\/h3>\n<ul>\n<li>State the likely inheritance type.<\/li>\n<li>Provide two pieces of evidence from the Pedigree Chart.<\/li>\n<li>Deduce one person\u2019s genotype (often the carrier).<\/li>\n<li>Give a probability if asked (show a short cross or logic).<\/li>\n<\/ul>\n<p><strong style=\"color: #f00;\">&gt;&gt;&gt; Read more:<\/strong> <a class=\"xem-them-link\" href=\"https:\/\/times.edu.vn\/en\/igcse\/igcse-biology-mistakes\/\">IGCSE Biology Mistakes in<\/a> 2026: Common Errors Students Make and How to Avoid Them<\/p>\n<h2><strong>Grade thresholds, examiner expectations, and why this changes your strategy<\/strong><\/h2>\n<p>Students often treat \u201cgrade boundaries\u201d as fixed percentages. Cambridge describes grade thresholds as minimum marks set <strong>after<\/strong>\u00a0each exam series has been taken and marked, which means difficulty adjustments happen later.<\/p>\n<h3><strong>What this means for your revision plan<\/strong><\/h3>\n<ul>\n<li>You cannot \u201caim for 80%\u201d as a universal rule because thresholds vary by series and component.<\/li>\n<li>You should train for <strong>reliable process marks<\/strong>, because those are stable across paper difficulty.<\/li>\n<li>You should review at least one official grade threshold table for your exam session to understand component weighting and performance expectations. Cambridge publishes subject\/component grade threshold tables (for example, Biology 0610 June 2025).<\/li>\n<\/ul>\n<h3><strong>The practical implication for IGCSE genetics questions<\/strong><\/h3>\n<p>Genetics is one of the best topics for \u201cpredictable marks,\u201d because:<\/p>\n<ul>\n<li>Punnett Squares, genotype deductions, and ratios are highly mark-scheme driven.<\/li>\n<li>If you standardize the method, you stop bleeding marks to avoidable slips.<\/li>\n<li>Even when questions are contextualized (diseases, plants, variation), the core scoring is consistent.<\/li>\n<\/ul>\n<p><strong style=\"color: #f00;\">&gt;&gt;&gt; Read more:<\/strong> <a class=\"xem-them-link\" href=\"https:\/\/times.edu.vn\/en\/igcse\/igcse-biology-study-plan\/\">IGCSE Biology Study Plan for<\/a> 2026: A Simple Revision Guide to Improve Your Exam Preparation<\/p>\n<h2><strong>Subject selection strategy for students targeting top universities<\/strong><\/h2>\n<p>Parents often focus on \u201cgetting an A*,\u201d but top university pathways reward <strong>coherent academic narrative<\/strong>. Based on our years of practical tutoring at Times Edu, the best strategy is aligning subject choices with intended major and ensuring your science-math load is sustainable.<\/p>\n<h3><strong>A selection framework we use in academic planning<\/strong><\/h3>\n<ul>\n<li>If your target is medicine\/biomed: Biology + Chemistry is non-negotiable in most pathways, and Mathematics strengthens competitiveness.<\/li>\n<li>If your target is engineering\/compsci: Mathematics + Physics is usually the anchor, with Chemistry or CS depending on school offering.<\/li>\n<li>If your target is economics\/business at selective universities: Mathematics is often the differentiator, and strong English\/essay subjects support admissions writing.<\/li>\n<\/ul>\n<p>A critical detail most students overlook in the 2026 exam cycle is that transcript \u201cshape\u201d matters: Too many disconnected subjects can weaken the story, even with strong grades.<\/p>\n<p>Your genetics performance supports a credible STEM profile, but only if your overall subject set reinforces it.<\/p>\n<p><strong style=\"color: #f00;\">&gt;&gt;&gt; Read more:<\/strong> <a class=\"xem-them-link\" href=\"https:\/\/times.edu.vn\/en\/igcse\/igcse-tutor\/\">IGCSE Tutor<\/a> 2026: How to Choose the Right One<\/p>\n<h2><strong>Frequently Asked Questions<\/strong><\/h2>\n<div class=\"hoi-dap-thok-new low-faq\">\n<div class=\"thong-tin-dai\">\n<p class=\"tit-dai\"><strong>How do you draw a Punnett square for IGCSE Biology?<\/strong><\/p>\n<div class=\"chi-tiet-thong-tin\">Write the two parent genotypes first, then list each parent\u2019s gametes along the top and side. Fill each box by combining one allele from each parent, then count genotypes and phenotypes to state ratios and probabilities. Use consistent allele letters and state which allele is dominant to avoid ambiguous marking.<\/div>\n<\/div>\n<div class=\"thong-tin-dai\">\n<p class=\"tit-dai\"><strong>What is the difference between homozygous and heterozygous?<\/strong><\/p>\n<div class=\"chi-tiet-thong-tin\"><strong>Homozygous<\/strong>\u00a0means two identical alleles (TT or tt), while <strong>heterozygous<\/strong>\u00a0means two different alleles (Tt). A heterozygous genotype can still show the dominant phenotype, so you must separate genotype from phenotype in your wording.<\/div>\n<\/div>\n<div class=\"thong-tin-dai\">\n<p class=\"tit-dai\"><strong>How to explain codominance in IGCSE genetics questions?<\/strong><\/p>\n<div class=\"chi-tiet-thong-tin\">Define codominance as both alleles being expressed in the heterozygote\u2019s phenotype. Then apply it by naming the heterozygous genotype and describing how both traits appear in the phenotype, rather than describing a blended outcome.<\/div>\n<\/div>\n<div class=\"thong-tin-dai\">\n<p class=\"tit-dai\"><strong>What are sex-linked characteristics and how are they inherited?<\/strong><\/p>\n<div class=\"chi-tiet-thong-tin\">Sex-linked characteristics are controlled by genes on the sex chromosomes, often the X chromosome. In X-linked recessive traits, males (XY) express the trait with one recessive allele on X, while females (XX) usually need two recessive alleles.<\/div>\n<\/div>\n<div class=\"thong-tin-dai\">\n<p class=\"tit-dai\"><strong>How do I define an allele in an exam?<\/strong><\/p>\n<div class=\"chi-tiet-thong-tin\">An <strong>allele<\/strong>\u00a0is an alternative form of a gene found at the same locus on a chromosome. You can add that different alleles arise from differences in DNA base sequence, which may affect the protein produced and the phenotype.<\/div>\n<\/div>\n<div class=\"thong-tin-dai\">\n<p class=\"tit-dai\"><strong>What is the ratio for a monohybrid cross?<\/strong><\/p>\n<div class=\"chi-tiet-thong-tin\">For a classic heterozygous cross (<strong>Tt \u00d7 Tt<\/strong>) with complete dominance, the genotype ratio is <strong>1:2:1<\/strong>\u00a0and the phenotype ratio is <strong>3:1<\/strong>. Always state what your ratio refers to (genotype or phenotype) to secure the mark.<\/div>\n<\/div>\n<div class=\"thong-tin-dai\">\n<p class=\"tit-dai\"><strong>How to interpret a pedigree chart for a recessive trait?<\/strong><\/p>\n<div class=\"chi-tiet-thong-tin\">Look for the trait skipping generations and for unaffected parents having an affected child, which supports recessive inheritance. Then label likely carriers as heterozygous and justify using evidence from the pedigree symbols, not assumptions.<\/div>\n<\/div>\n<\/div>\n<h4>Conclusion<\/h4>\n<p>Based on our years of practical tutoring at <a href=\"https:\/\/times.edu.vn\/en\/\">Times Edu<\/a>, we do not \u201cteach genetics\u201d; we engineer exam outcomes through targeted drills and error-proofing.<\/p>\n<p>We map your recurring mistakes (letter choice, gamete setup, ratio wording, pedigree logic) to a personal checklist, then train you until the method is automatic.<\/p>\n<p>If you share your exam board (Cambridge 0610 or another IGCSE specification), paper combination, and your latest mock marks by topic, Times Edu can build a personalized genetics + inheritance sprint plan with weekly targets, past-paper question sets, and marking feedback that mirrors examiner logic.<\/p>\n<p>Cambridge publishes syllabus guidance for 2026\u20132028, and aligning your practice to that framework is the fastest way to convert revision time into grades.<\/p>\n\n\n<div class=\"kk-star-ratings kksr-auto kksr-align-right kksr-valign-bottom\"\n    data-payload='{&quot;align&quot;:&quot;right&quot;,&quot;id&quot;:&quot;37971&quot;,&quot;slug&quot;:&quot;default&quot;,&quot;valign&quot;:&quot;bottom&quot;,&quot;ignore&quot;:&quot;&quot;,&quot;reference&quot;:&quot;auto&quot;,&quot;class&quot;:&quot;&quot;,&quot;count&quot;:&quot;1&quot;,&quot;legendonly&quot;:&quot;&quot;,&quot;readonly&quot;:&quot;&quot;,&quot;score&quot;:&quot;5&quot;,&quot;starsonly&quot;:&quot;&quot;,&quot;best&quot;:&quot;5&quot;,&quot;gap&quot;:&quot;5&quot;,&quot;greet&quot;:&quot;\u0110\u00e1nh gi\u00e1 b\u00e0i vi\u1ebft&quot;,&quot;legend&quot;:&quot;5\\\/5 - (1 vote)&quot;,&quot;size&quot;:&quot;24&quot;,&quot;title&quot;:&quot;IGCSE Biology Genetics Questions 2026: Punnett Squares + Pedigree A*&quot;,&quot;width&quot;:&quot;142.5&quot;,&quot;_legend&quot;:&quot;{score}\\\/{best} - ({count} {votes})&quot;,&quot;font_factor&quot;:&quot;1.25&quot;}'>\n            \n<div class=\"kksr-stars\">\n    \n<div class=\"kksr-stars-inactive\">\n            <div class=\"kksr-star\" data-star=\"1\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"2\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"3\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"4\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"5\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n    <\/div>\n    \n<div class=\"kksr-stars-active\" style=\"width: 142.5px;\">\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n    <\/div>\n<\/div>\n                \n\n<div class=\"kksr-legend\" style=\"font-size: 19.2px;\">\n            5\/5 - (1 vote)    <\/div>\n    <\/div>\n","protected":false},"excerpt":{"rendered":"<p>IGCSE\u00a0genetics questions mainly test how accurately you apply inheritance rules, not how much you can memorize. You\u2019re expected to define core terms like allele, genotype, phenotype, homozygous and heterozygous, then use a Punnett square to solve a monohybrid cross and state genotype\/phenotype ratios. Higher-mark items often add codominance, sex-linked disorders, DNA-to-trait reasoning, and pedigree chart &#8230; <a title=\"IGCSE Biology Genetics Questions 2026: Punnett Squares + Pedigree A*\" class=\"read-more\" href=\"https:\/\/times.edu.vn\/en\/igcse\/igcse-genetics-questions\/\" aria-label=\"Read more about IGCSE Biology Genetics Questions 2026: Punnett Squares + Pedigree A*\">Read more<\/a><\/p>\n","protected":false},"author":7,"featured_media":37984,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"content-type":"","rank_math_title":"","rank_math_description":"Master IGCSE Biology genetics questions: Punnett squares (mono\/dihybrid), pedigree analysis, sex-linked inheritance, blood types. Worked examples + past paper practice for A*.","footnotes":""},"categories":[166],"tags":[],"class_list":["post-37971","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-igcse"],"_links":{"self":[{"href":"https:\/\/times.edu.vn\/en\/wp-json\/wp\/v2\/posts\/37971","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/times.edu.vn\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/times.edu.vn\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/times.edu.vn\/en\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"https:\/\/times.edu.vn\/en\/wp-json\/wp\/v2\/comments?post=37971"}],"version-history":[{"count":3,"href":"https:\/\/times.edu.vn\/en\/wp-json\/wp\/v2\/posts\/37971\/revisions"}],"predecessor-version":[{"id":39552,"href":"https:\/\/times.edu.vn\/en\/wp-json\/wp\/v2\/posts\/37971\/revisions\/39552"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/times.edu.vn\/en\/wp-json\/wp\/v2\/media\/37984"}],"wp:attachment":[{"href":"https:\/\/times.edu.vn\/en\/wp-json\/wp\/v2\/media?parent=37971"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/times.edu.vn\/en\/wp-json\/wp\/v2\/categories?post=37971"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/times.edu.vn\/en\/wp-json\/wp\/v2\/tags?post=37971"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}