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A plant species may have red or white flowers - HSC - SSCE Biology - Question 16 - 2008 - Paper 1
Question 16
A plant species may have red or white flowers. Two red-flowered plants were crossed. Most of the offspring had red flowers, but some had white flowers. Explain the ... show full transcript
Worked Solution & Example Answer:A plant species may have red or white flowers - HSC - SSCE Biology - Question 16 - 2008 - Paper 1
Step 1
Explain the presence of both red- and white-flowered offspring
Answer
The presence of both red- and white-flowered offspring can be explained through basic principles of genetics, particularly Mendelian inheritance.
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Genetic Factors: The red flower trait is likely dominant over the white flower trait. This means that if a plant has at least one allele for red flowers (R), it will exhibit red flowers.
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Parental Genotypes: In this case, both parents are red-flowered. This could imply that they are homozygous (RR) or heterozygous (Rr) for the red flower trait. If both parents are heterozygous (Rr), then the offspring could inherit combinations of alleles, leading to different flower colors.
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Punnett Square Analysis: When crossing two heterozygous red-flowered plants (Rr x Rr), a Punnett square reveals the following genotype ratios: 1 RR (red), 2 Rr (red), and 1 rr (white). Therefore, the expected phenotypic ratio would be 3 red : 1 white.
Thus, the offspring showing both phenotypes is the result of a combination of genetic inheritance from the red-flowered parent plants.