Genetic inheritance
This topic explains the principles of genetic inheritance. Students will learn about dominant and recessive alleles, homozygous and heterozygous genotypes, and the use of Punnett squares.
Full topic guide: the detailed syllabus page with worked examples and common mistakes lives at studyvector.co.uk/gcse/biology/inheritance-variation-evolution/genetic-inheritance.
Topic preview: Genetic inheritance
Sample stems from the StudyVector question bank (AQA · Edexcel · OCR) — not generic filler text.
More questions are being linked to this topic. You can still start low-focus cards after you create a free account.
Coverage and provenance
What this page is based on
StudyVector does not present unsupported question coverage as complete. Read how questions are selected and reviewed.
Topic explanation
Genetic inheritance is the process by which genetic information is passed from parent to offspring. Key terms include allele (different versions of a gene), genotype (the combination of alleles an individual has), and phenotype (the observable characteristics resulting from the genotype). Dominant alleles are always expressed, while recessive alleles are only expressed if two copies are present.
Genetic inheritance is easiest to revise when it is treated as a precise exam behaviour, not a loose note-taking category. In GCSE Biology, the goal is to recognise how the topic appears in a question, identify the command word, and decide what evidence, method, or vocabulary earns marks. StudyVector keeps this page tied to AQA · Edexcel · OCR language where coverage is available, then routes practice towards the same topic so revision moves from explanation into retrieval.
A strong revision session starts with a short recall check. Write down the rule, definition, process, or method linked to Genetic inheritance before looking at any notes. Then answer one exam-style prompt and compare your answer with the mark-scheme logic: did you make a clear point, support it with the right step, and avoid drifting into a nearby topic? This matters because many lost marks come from almost-correct answers that do not match the expected structure.
Use this guide as the first layer: understand the topic, look at the worked examples, complete the mini quiz, then move into full practice. The full StudyVector practice loop is designed to capture whether mistakes are caused by knowledge, method, language, or timing. That distinction is important. If the error is factual, you need reteaching. If the error is method-based, you need a worked retry. If the error is wording, you need command-word calibration. That is how Genetic inheritance becomes a controlled revision target rather than another page in a folder.
Lost marks → repair task
Why marks are usually lost here
These are the error patterns StudyVector looks for after an attempt. The goal is not a generic explanation; it is one repair move and one follow-up question.
Command-word miss
Examiner move: Answer the action in the command word before adding extra detail.
Repair drill: 60-second rewrite: start the answer with explain, compare, evaluate, state, or calculate in mind.
Weak evidence or data reference
Examiner move: Use a precise value, quote, example, diagram feature, or syllabus term to support the claim.
Repair drill: Add one concrete reference to the answer and remove any generic sentence that does not earn a mark.
Missing chain of reasoning
Examiner move: Show the link between point, method, evidence, and conclusion instead of jumping to the final line.
Repair drill: Write the missing because/therefore step, then retry one isomorphic question.
Mini quiz
Use these checks before full practice. They test topic recognition, exam technique, and whether you can connect the explanation to a marked response.
1. What should you check first when a Genetic inheritance question appears in GCSE Biology?
- A.The command word and the exact topic focus
- B.The longest paragraph in your notes
- C.A memorised answer from a different topic
2. Which revision action gives the strongest evidence that Genetic inheritance is improving?
- A.Rereading the explanation twice
- B.Answering a timed exam-style question and reviewing lost marks
- C.Highlighting every key phrase in the topic notes
Sample questions
Topic-specific public question previews are still being reviewed. We keep them off public pages until the topic match is safe.
Exam tips
- Read the command word carefully — "explain" needs reasons; "state" expects a short fact.
- For Genetic inheritance, show structured working even when you are practising multiple choice — it builds accuracy under time pressure.
- Mark yourself against the mark scheme style: one clear point per mark, in logical order.
- Come back to this topic after a day or two; short spaced reviews beat one long cram.
Worked examples
Example 1
Modelled exam response
In pea plants, the allele for purple flowers (P) is dominant to the allele for white flowers (p). If a heterozygous plant (Pp) is crossed with a white-flowered plant (pp), a Punnett square shows there is a 50% chance of the offspring having purple flowers (Pp) and a 50% chance of them having white flowers (pp).
Example 2
Identify the task before answering
Question type: a Genetic inheritance prompt asks for a clear response in GCSE Biology. Step 1: underline the command word. Step 2: name the exact part of Genetic inheritance being tested. Step 3: decide whether the mark scheme wants a definition, method, explanation, comparison, or calculation. Why it works: most weak answers fail before the content starts because they answer the topic generally rather than the exact exam task.
Example 3
Turn feedback into a repair task
Suppose your answer shows partial understanding but loses marks for precision. First, rewrite the missing mark as a short target: "I need to state the mechanism, unit, reason, or evidence explicitly." Then answer one similar question without notes. Finally, compare the second attempt with the first and check whether the same mark was recovered. Why it works: Genetic inheritance improves faster when feedback creates a specific retry, not another passive reading session.
Next revision routes from this subject
Good topic pages should lead naturally into the next useful page. Use these links to stay inside the same strand or jump into the next topic area without starting your search again.
Stay in the same topic area
Explore the wider subject map
Common mistakes
- Confusing genes and alleles. A gene is a section of DNA for a characteristic (e.g., eye colour gene), while alleles are the different versions of that gene (e.g., blue eye allele, brown eye allele).
- Thinking the dominant phenotype is always the most common. Dominance refers to which allele is expressed, not how frequent it is in a population. For example, the allele for Huntington's disease is dominant but rare.
- Getting heterozygous and homozygous mixed up. Homozygous means having two identical alleles for a gene (e.g., BB or bb), while heterozygous means having two different alleles (e.g., Bb).
Exam board notes
Covered by all major boards (AQA, Edexcel, OCR). The use of Punnett squares to predict outcomes of monohybrid crosses is a key skill.
FAQs
What is the difference between genotype and phenotype?
The genotype is the genetic makeup of an organism, i.e., the specific alleles it carries (e.g., Bb). The phenotype is the physical expression of those alleles, i.e., the observable characteristic (e.g., brown eyes).
What is a Punnett square used for?
A Punnett square is a diagram used to predict the possible genotypes and phenotypes of offspring from a genetic cross. It shows all the possible combinations of alleles from the parents' gametes.
More on StudyVector
Full practice set
The complete adaptive question bank for this topic — personalised to your weak areas — is available after you sign in. Your session can start on this topic immediately.