Mendel crossed pea plants that were heterozygous for different characteristics.
The Table shows some of his results for the offspring.
Table
| Characteristic | Dominant phenotype | Number of offspring | Recessive phenotype | Number of offspring |
|---|---|---|---|---|
| seed shape | round | 5474 | wrinkled | 1850 |
| seed colour | yellow | 6022 | green | 2001 |
| pod colour | green | 428 | yellow | 152 |
| stem length | tall | 787 | short | 277 |
Calculate the ratio of round seeds to wrinkled seeds.
Give your answer in the form x:1 x:1\,x:1 to two decimal places.
Explain why the results are not exactly in the ratio 3:13:13:1.
Explain why Mendel used large numbers of plants in his experiments.
Mendel suggested that each characteristic is controlled by a pair of inherited factors and that only one factor from each pair passes into each gamete.
Explain how Mendel's ideas match the modern understanding of genes and alleles.
43 exam-style questions on Edexcel GCSE Biology 3.3 Inheritance, covering 3.3.1 Gregor Mendel and the basis of genetics, 3.3.2 Alleles and inherited characteristics, 3.3.3 Monohybrid inheritance, 3.3.4 Determination of sex at fertilisation, 3.3.5 Outcomes from monohybrid crosses, 3.3.6 Inheritance of ABO blood groups, 3.3.7 Inheritance of sex-linked disorders, and 3.3.8 Multiple genes and phenotypic features. Each one has a worked solution and a mark scheme showing where the marks go.