Inheritance

Worked examples (6)

• 1Reading pedigree symbols (Getting started)
• 2What the connecting lines mean (Getting started)
• 3Dominant or recessive? (Building confidence)
• 4Deduce the genotypes (Building confidence)
• 5When the genotype is uncertain (Stretch)
• 6Probability of an affected child (Stretch)

Model answers (6)

• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style — extended open response
• ✓Model answer — 4WSD0/1B style — extended open response

Worked examples (6)

• 1Identify a polygenic feature (Getting started)
• 2Genotypes and phenotypes (Getting started)
• 3Complete a Punnett square for Tt × Tt (Building confidence)
• 4Predict the cross Tt × tt (Building confidence)
• 5Predict a probability from a cross (Stretch)
• 6Work backwards from the offspring (Stretch)

Model answers (6)

• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style — extended open response
• ✓Model answer — 4WSD0/1B style — extended open response

Worked examples (6)

• 1Choosing letters for alleles (Getting started)
• 2Which genotype shows the recessive feature? (Getting started)
• 3Sorting homozygous and heterozygous (Building confidence)
• 4Same phenotype, different genotype (Building confidence)
• 5Describe a genotype using all six terms (Stretch)
• 6Explain the difference between genotype and phenotype (Stretch)

Model answers (6)

• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style — extended open response
• ✓Model answer — 4WSD0/1B style — extended open response

Worked examples (6)

• 1State the sex chromosomes (Getting started)
• 2Which gamete carries which chromosome (Getting started)
• 3Draw the Punnett square for sex (Building confidence)
• 4Work out the probability of a girl (Building confidence)
• 5Chance of the next child being a boy (Stretch)
• 6Explain how sex is determined at fertilisation (Stretch)

Model answers (6)

• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style — extended open response
• ✓Model answer — 4WSD0/1B style — extended open response

Worked examples (6)

• 1Name the division that makes identical cells (Getting started)
• 2Four processes that use mitosis (Getting started)
• 3Chromosome number after mitosis (Building confidence)
• 4Why daughter cells are clones (Building confidence)
• 5Describe what happens in mitosis (Stretch)
• 6Why growth uses mitosis, not meiosis (Stretch)

Model answers (6)

• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style — extended open response
• ✓Model answer — 4WSD0/1B style — extended open response

Worked examples (6)

• 1Where meiosis happens and what it makes (Getting started)
• 2Products of meiosis (Getting started)
• 3Working out the gamete chromosome number (Building confidence)
• 4Two differences between meiosis and mitosis (Building confidence)
• 5Why genetically different gametes are an advantage (Stretch)
• 6Describe how meiosis produces gametes (Stretch)

Model answers (6)

• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style — extended open response
• ✓Model answer — 4WSD0/1B style — extended open response

Worked examples (6)

• 1Define fertilisation (Getting started)
• 2How meiosis sets up variation (Getting started)
• 3Explain what 'random fertilisation' means (Building confidence)
• 4Why brothers and sisters differ (Building confidence)
• 5Link meiosis to genetic variation (Stretch)
• 6Why genetic variation is an advantage (Stretch)

Model answers (6)

• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style — extended open response
• ✓Model answer — 4WSD0/1B style — extended open response

Worked examples (6)

• 1Define variation (Getting started)
• 2Classify genetic and environmental features (Getting started)
• 3Why height is combined variation (Building confidence)
• 4Continuous versus discontinuous variation (Building confidence)
• 5Classify and justify a feature (Stretch)
• 6Linking variation type to graph shape (Stretch)

Model answers (6)

• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style — extended open response
• ✓Model answer — 4WSD0/1B style — extended open response

Worked examples (6)

• 1Define a mutation (Getting started)
• 2Name some mutagens (Getting started)
• 3Classify the effects of mutations (Building confidence)
• 4Which mutations are inherited? (Building confidence)
• 5Mutation and natural selection in bacteria (Stretch)
• 6Mutagens and mutation rate (Stretch)

Model answers (6)

• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style — extended open response
• ✓Model answer — 4WSD0/1B style — extended open response

Worked examples (6)

• 1State the human diploid number (Getting started)
• 2State the human haploid number (Getting started)
• 3Work out a haploid number (Building confidence)
• 4Fertilisation restores the diploid number (Building confidence)
• 5Explain why gametes are haploid (Stretch)
• 6What if gametes were diploid? (Stretch)

Model answers (6)

• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style — extended open response
• ✓Model answer — 4WSD0/1B style — extended open response

Worked examples (6)

• 1Who and what (Getting started)
• 2Where variation comes from (Getting started)
• 3Survival of the fittest (Building confidence)
• 4Passing on the advantage (Building confidence)
• 5Faster prey evolving (Stretch)
• 6Camouflage by natural selection (Stretch)

Model answers (6)

• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style — extended open response
• ✓Model answer — 4WSD0/1B style — extended open response

Worked examples (6)

• 1What antibiotics act against (Getting started)
• 2Where resistance comes from (Getting started)
• 3Order the natural-selection steps (Building confidence)
• 4Why MRSA is hard to treat (Building confidence)
• 5Explain how a resistant population develops (Stretch)
• 6Why overuse of antibiotics matters (Stretch)

Model answers (6)

• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style
• ✓Model answer — 4WSD0/1B style — extended open response
• ✓Model answer — 4WSD0/1B style — extended open response