Question 4 (2 marks)

The genotype of the F1 plants is: [Fill in the blank],

The phenotype of the F1 plants is: [Fill in the blank],

Question

Question 4 (2 marks)

The genotype of the F1 plants is: [Fill in the blank],

The phenotype of the F1 plants is: [Fill in the blank],

BlackTom AI · Accepted Answer

The question presents two fill-in-the-blank prompts for an F1 generation:

- The genotype of the F1 plants is: [Fill in the blank]
- The phenotype of the F1 plants is: [Fill in the blank]

The provided answers are:
- Genotype: RrSs
- Phenotype: purple flowers and long pollen grains

First, consider what the two blanks are asking for. The genotype blank asks for the combination of alleles that makes up the F1 individuals across two genes (a dihybrid). The phenotype blank asks for the outward traits corresponding to those alleles.

Option-by-option reasoning (even though there are no multiple-choice options here, we analyze the two supplied items):

- Analyzing the genotype 'RrSs': This indicates the plant is heterozygous at both gene loci (one dominant and one recessive allele for each gene). If the cross involved at least one parent providing dominant and recessive alleles for each gene, F1 plants being RrSs is consistent with a dihybrid cross where both traits segregate independently according to Mendel’s law of independent assortment. In such a scenario, the F1 genotype would typically be RrSs when the parental cross were something like RRss x rrSS or similar, yielding heterozygotes for both genes in the offspring. The key point is that 'RrSs' shows heterozygosity at both loci, not homozygosity.

- Analyzing the phenotype 'purple flowers and long pollen grains': This interpretation relies on the dominance hierarchy for each gene. If 'R' is the dominant allele for purple flowers and 'S' is the dominant allele for long pollen grains, then the genotype 'RrSs' would express the dominant phenotypes for both traits, namely purple flowers and long pollen grains. Thus, this phenotype description is consistent with the genotype RrSs under a typical dominant-recessive model where R > r causes purple flowers and S > s causes long pollen grains.

Potential caveats and misconceptions to watch for:

- If the trait model were not simple dominance (e.g., incomplete dominance or co-dominance), the phenotype for Rr would not be as straightforward as 'purple' unless the dominant relationship is specified. Similarly for 'S' and pollen grain length. The two blanks assume a classic dominant-recessive interpretation unless stated otherwise.

- If the cross that produced F1 is not known, stating the genotype as RrSs is a plausible general answer for a dihybrid cross resulting in heterozygous offspring, but it is not guaranteed without knowing the parental genotypes. The phenotype answer likewise assumes dominant phenotypes for both traits.

- Absence of provided answer options means we cannot compare alternatives, so the evaluation hinges on consistency with standard Mendelian dihybrid expectations rather than specific cross details.

In summary, the genotype RrSs denotes heterozygosity at both gene loci, which is a common result in a dihybrid cross, and the phenotype purple flowers and long pollen grains aligns with the assumption that the dominant alleles R and S determine those traits. The reasoning depends on standard dominance relationships and independent assortment.

AGRI30048_2025_SM2 Quiz 1

Question 4 (2 marks) The genotype of the F1 plants is: [Fill in the blank], The phenotype of the F1 plants is: [Fill in the blank],

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