A diploid plant species has a gene controlling petal colour with three alleles: CRC^RCR, CWC^WCW, and CYC^YCY. The alleles CR C^R\,CR and CW C^W\,CW are codominant (producing pink petals when inherited together), while CY C^Y\,CY is recessive to both.
Which of the following statements regarding the inheritance of this trait is correct?
A cross between a pink-flowered plant (CRCWC^R C^WCRCW) and a white-flowered heterozygous plant (CWCYC^W C^YCWCY) will yield offspring with a phenotypic ratio of 1 red : 2 pink : 1 white.
In a population of these plants, there are six possible genotypes but only four distinct phenotypes for this gene.
A cross between two pink-flowered plants can produce offspring with yellow petals (CYCYC^Y C^YCYCY) if both parents carry the recessive CYC^YCY allele.
Because there are three alleles for this gene, a single male gamete (pollen grain) from a heterozygous plant can carry up to two different alleles.
97 exam-style questions on OCR GCSE Biology 5.1 Inheritance, covering 5.1.1 The genome, 5.1.2 Environment and phenotype, 5.1.3 Variants and mutations, 5.1.4 How genetic variants influence phenotype, 5.1.5 Asexual and sexual reproduction, 5.1.6 Haploid and diploid, 5.1.7 Meiotic cell division, 5.1.8 Single gene inheritance, 5.1.9 Predicting single gene crosses, 5.1.10 Sex determination, 5.1.11 Multiple gene inheritance, and 5.1.12 Development of our understanding of genetics. Each one has a worked solution and a mark scheme showing where the marks go.