In pea plants, the allele for tall stems, TTT, is dominant to the allele for short stems, ttt.
Two heterozygous pea plants were crossed.
The Table shows a Punnett square for this cross.
Table
| Gametes | TTT | ttt |
|---|---|---|
| TTT | TTTTTT | R |
| ttt | S | tttttt |
Give the genotypes of offspring R and offspring S.
State the phenotype of offspring with the genotype tttttt.
Give the expected ratio of tall plants to short plants.
The cross produced 240 seeds.
Calculate the number of seeds expected to grow into short plants.
Explain why two tall parent plants can produce some short offspring.
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.